#elementary-number-theory

1 messages · Page 62 of 1

obtuse mason
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I mean I'm not looking for a solution more a direction

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that's why I dont want to look on the web

winter bear
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well a^b+1, looking at this form whats the first thing that comes to ur mind

obtuse mason
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fermat

winter bear
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hmm, its more direct than that

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a^b+1^b, if that helps

obtuse mason
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thank you for the hint

jovial hemlock
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can someone explain the Chinese Remainder theorem to me? it keeps coming up and I can’t make sense of the wikipedia article on it

winter bear
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hmm how much algebra do you know(ring theory etc)

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if not we'll go for a more elementery aproach

jovial hemlock
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I’m in linear algebra (matrix theory) now

winter bear
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hmm ok try reading this, its well written

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you can inquire about anything that confuses ya

jovial hemlock
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okay thanks

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brb

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I don’t understand this statement about extended euclidean algorithm

winter bear
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its essentially to find the inverses

alpine jasper
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an example probably will help

jovial hemlock
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“It is wellknown that if gcd(a,b) = r then integers p and s exist where p(a) + s(b) = r”

winter bear
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(bezo'uts)

jovial hemlock
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but

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the gcd of a and b is at most the size of the smallest one

winter bear
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can be negative

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p,s

jovial hemlock
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how can you multiply a and b by... wait negative numbers nvm

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(bezo’uts)

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?

winter bear
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its the name of that

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bezo'uts identity

jovial hemlock
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ah

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okay so

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the extended euclidean algorithm finds the modular inverse of n

winter bear
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yep

jovial hemlock
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but the eea seems to require a lot of iteration

winter bear
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its relatively efficient, but this is not really the important part. The important part is to get the theory that there are inverses and what follows

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(if ur doing problems by hand usually finding inverses will be easy, and if not then computers already have eea coded)

jovial hemlock
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okay back to CRT

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on that page, y1^-1 literally means 1/y1 or no?

winter bear
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wherever thers ^(-1)s or 1/something, it means modular inverse

jovial hemlock
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so i’m confused as to what step 3 is saying

winter bear
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its just asking for the inverses of each y_i

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which we defined before hand

jovial hemlock
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with respect to what

winter bear
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umm it says mod n_i

jovial hemlock
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like you can’t say the modular inverse of x

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you have to say the modular inverse of x to 26

winter bear
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i mean it literally says what mod tho

jovial hemlock
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oh

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ohhh

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so it’s defining zi as being the modular inverse of yi to ni

winter bear
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yep

jovial hemlock
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I don’t get why it’s so complicated

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like, intuitively it seems like it’s not that hard to find a number satisfying multiple modulos

winter bear
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well its not really easy to do so

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like think about inverses, even those arent easy to find

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the existence itself isnt hard to show with less tedium, but to actually compute it is annoying yeah

jovial hemlock
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but like

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if you were to say a number is 5 mod 12 and 9 mod 20

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I can easily think to myself, well, the LCM of those is 60 so it’s X mod 60

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and then I think, what numbers are 9 mod 20? well, 9, 29, and 49

winter bear
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well you dont need to check a lot of things, u only need to check a few here

jovial hemlock
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and only one of those is 5 mod 12

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I’m guessing that the second step is what makes it hard?

winter bear
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yeah like if u have 3 numbers its p easy to see it right

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but if u have bigger numbers i think this is inefficient compared to the other algorithims

jovial hemlock
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but which step is the hard part?

winter bear
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step 2

jovial hemlock
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finding the list of things 9 mod 20 or figuring out which of those is 5 mod 12?

winter bear
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the latter

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(also imagine having more mods to consider, that becomes more inefficient, like instead of 2 if you had 5)

jovial hemlock
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I only care about 2 at the moment

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Say you have a number

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and you know it’s a mod c and b mod d

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and c is larger

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I’d think you could find y = d - c mod d if c mod d =/= 0 and 0 if c mod d = 0

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hang on a sec let me

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okay I think it’s like this

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you have a number X

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a = x mod c and b = x mod d
c > d

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let y = d - (c mod d)
let z = (a-b) mod d
let n = (z/y) c + a

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then n = x mod (LCM(c,d))

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I don’t know how to prove it but I think that’s right

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no need for c and d to be xp prime btw

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oh, and if c mod d = 0 then the LCM is already c so it’s trivial

obtuse mason
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a^b + 1 is prime, then a even and b is power of two
Okay a has to be even, because otherwise (a^b + 1) would be even and therefore divisible by 2

jovial hemlock
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why is it prime?

winter bear
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yeah thats one part

jovial hemlock
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oh wait you’re a different discussion

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John, who are you responding to?

winter bear
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deekaan

obtuse mason
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the second part I can't figure out why

winter bear
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well a^b+1^b

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think about factors

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also notch im p sure this isjust what the wiki says for 2 primes

jovial hemlock
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what wiki

winter bear
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the brilliant one i sent you

jovial hemlock
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and wdym two primes?

winter bear
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or sorry 2 mods

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(typically CRT is used with primes so i said primes)

jovial hemlock
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where does it say that?

winter bear
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i mean i just glanced at it, but urs should be equivalent to the algo they have

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for the case of two mods

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otherwise its incorrect

jovial hemlock
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the only algorithms I see there are iterative though and mine isn’t at all

obtuse mason
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The second part is because of factorization, if b is uneven then the expression (a^b + 1) = (a + 1)(***)

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and if its not a factor of 2 then it can be turned into an uneven factor using prime factorization

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is this right?

winter bear
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yep

obtuse mason
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okay wow thank you very much

queen locust
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Alright, I am stuck, i got this problem which I need to solve:

swift shard
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$\frac{x_1+x_2+...+x_n}{n}\geq(x_1x_2...x_n)^{1/n},~ \forall n=2^k,~ k\geq1,~ \text{and}~ x_1,x_2,...,x_n>0.$

sterile pumiceBOT
queen locust
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thank you

swift shard
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Yaya we just use $ surrounding here

queen locust
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aight, will keep in mind

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I went through the whole method for induction problems

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I started with assuming that it's true for a k, and went from there

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however i couldnt do anything with the expression for only k, so I thought I'd work with k+1 instead

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that didnt help either

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so any advice or tip is appreciated, however no solutions please heh

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I've managed to get this, dont know if it's useful tho

craggy solstice
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ok i think i got it

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so uh what i did is rewrite the (x1.x2.x3..xN)^1/N where N=2^k as k products with two terms each

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like (x1.x2)^1/2^k

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now ${(x1.x2)}^{1/2^k}<=(x1.x2)^{0.5}<=0.5*(x1+x2)$

sterile pumiceBOT
craggy solstice
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latex is aids but tolerate

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no actually i skipped alot of steps

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this is what i was trying to get at

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you can use the same method for higherpowers

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the steps will just be repeated

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@queen locust

jovial hemlock
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so

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I don’t want to type out my question again let me screenshot

sacred junco
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how do you find num of solutions to a polynomial congruence that could look like a quadratic poly with substituion?

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i.e $x^{20}+30x^{10}+300=0 \pmod{249}$

sterile pumiceBOT
sacred junco
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you could rewrite this to $z^2+30z+300=0\pmod{249}$ and then you would use lagranges numbers to find number of solutions to this

sterile pumiceBOT
sacred junco
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but i dont think this is right because x^20 can have at most 20 solutions while ^2 will have at most 2

light flicker
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That's not true

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The equation x² = 1 (mod 8) has 4 solutions

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You need to be careful when working with composite modulus, so your first step should always be to use Chinese remainder theorem to split things apart into prime modulus

sacred junco
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i must have messsed it up with roots

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assuming the mod is already prime?

light flicker
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It doesn't matter x² - 1 = 0 (mod 8) has 4 roots

sacred junco
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im wrongly remembering some other fact then

light flicker
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It's true if the modulus is prime

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And that's why you want to use crt to work with prime mod instead

sacred junco
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the odd number i wrote was supposed to be prime

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as mod

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i forgot to mention i have a prime modulus

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and the 249 i typoed wasnt prime

light flicker
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Then the problem is that z will have two solutions

sacred junco
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but x could have up to 20

light flicker
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But you have that x^10 = z

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So there will be ten solutions (counting multiplicities) for x for each solution of z

sacred junco
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but then you have to rule out the multiplicitites and to find the number of unique solutions you need to enumerate the solutions

light flicker
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you can use quadratic/5-th power residue things to say how many solutions you have

sleek cove
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is it necessary to prove that eulers function is strictly nondecreasing

light flicker
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its uh

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not?

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phi(7) = 6, phi(8) = 4?

sleek cove
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wait nvm

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sory

jovial hemlock
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is that right?

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and if so how do I prove it

wild zinc
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I don't think so

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let c = d+1, for example. then y = d-1, z = a-b so n = (a-b)(d+1)/(d-1) + a which is not necessarily an integer

jovial hemlock
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z =/= (a-b) though

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it equals (a-b) mod d

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let’s try a = 2 c = 20 b = 3 d = 19

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y = 19-(20mod19) = 18

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z = (2-3) mod 19 = 18

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18 * 20/18 + 2 = 22 which is correct

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@wild zinc

wild zinc
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a-b is kinda irrelevant because it's arbitrary

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you would have to have (d+1)/(d-1) an integer

jovial hemlock
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no it isn’t

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what a-b does is essentially cycle it

wild zinc
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your claim is that this holds for all a,b?

jovial hemlock
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for all a,b and c,d yes, assuming there is a solution

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so it wouldn’t hold for 3 mod 18 and 2 mod 16 for example

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but if there is a solution with a,b I think this finds it. I’m not sure why though.

wild zinc
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what about a = 1, b = 0, c = 17, d = 18

jovial hemlock
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c is the bigger one remember

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so it would be a = 0, b = 1, c = 18, d = 17

wild zinc
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oh right

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still shouldn't work

jovial hemlock
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y = 17-(18mod17) = 16
z = (0-1)mod17 = 16
16/16 * 18 + 0 = 18

wild zinc
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a=1,b=0 shouldn't work tho

jovial hemlock
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oh, a = 1, b = 0, c = 18, d = 17?

wild zinc
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maybe

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yeah, I forgot which way round I did the +1

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we get 9/8 + 1

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I think if you let the division be modular inverse then it holds but

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this has the same problem of requiring modular inverse calculation

jovial hemlock
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hang on

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is there an easy way to manually check numbers

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like somewhere I can put these equations and change numbers on the fly

torn escarp
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learn some basic python and program it

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easily brute force check for counter examples

jovial hemlock
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what I don’t know how to do is test only valid a,b pairs

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I wouldn’t want it stopping on 0 mod 2 and 1 mod 4 for example

torn escarp
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what is the criteria for being a valid pair

jovial hemlock
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I think that A and B have to be equivalent modulo (GCD(c,d))?

torn escarp
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then only test ones that satisfy that

jovial hemlock
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is that correct condition?

torn escarp
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I have no clue, why are you asking me

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I didn't read the problem, it didn't interest me

jovial hemlock
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you were responding to my questions about the problem

torn escarp
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but I'm just offering to help you set up your program

jovial hemlock
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ah

torn escarp
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but you don't know what the criteria is to check so I can't help, good luck

jovial hemlock
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I assume that’s it

torn escarp
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sounds sketchy

jovial hemlock
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just

torn escarp
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you only want to check the true cases to know what's true...?

jovial hemlock
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the criteria I want is for one number to be a mod c and b mod d

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and I’m testing how to find that number

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and I only want to check cases where that number exists

torn escarp
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I see

jovial hemlock
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which python version do I get? python 3 or python 2?

torn escarp
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3

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I'd download visual studio code if I were you

jovial hemlock
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what’s that

torn escarp
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and then I think it will take care of getting the stuff you need from addons in it

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it's an IDE

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basically like, spell check for code

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and runs code too

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like, very roughly speaking lol

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might be better to find a kind of tutorial or something to learn some from since you might have to learn a few things before you can write a few for loops to get what you want but it shouldn't be too far off

jovial hemlock
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no I have basic python experience

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It’ll just take me a bit to refresh and check how to use mod operator and that sort of thing

sacred junco
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if I have p = 3 mod 4 and a =/= 0 mod p, how would I go about showing either -a or a == b^2 mod p where b is some integer?

light flicker
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this would follow from the fact that -1 isn't a square mod p

sacred junco
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Could you please explain more?

jovial hemlock
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I can’t figure out

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how to use this

torn escarp
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visual studio code?

jovial hemlock
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yeah

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it won’t run anything

torn escarp
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it might recognize the file name and ask if you wanna add stuff

jovial hemlock
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I think I’m used to the version 2

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gonna try that

torn escarp
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it'll give you a run button at the top right once you install what it prompts

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possible

jovial hemlock
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oh wait do I need to name it .py?

torn escarp
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yes

jovial hemlock
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oh okay thanks

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I had it as a .txt no wonder

torn escarp
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lol yeah that would do it

light flicker
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@sacred junco there's a fact that the product of two things that aren't squares mod p is a square mod p

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So like if a and b are both not squares mod p, then ab has to be a square mod p

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So if -1 isn't a square mod p and a isn't either, then -a has to be a square mod p

jovial hemlock
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can you help me?

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I probably just messed something up but my code isn’t working and I’m not sure why

torn escarp
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copy paste it

jovial hemlock
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hang on let me open discord on my computer

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import math
for c in (3,100):
for d in (2,c-1):
lcm = (c*d/math.gcd(c,d))
for x in (0,lcm-1):
a = math.fmod(x,c)
b = math.fmod(x,d)
y = d - math.fmod(c,d)
z = math.fmod((a-b),d)
if z == 0:
n = 0
elif z > y:
n = (z/y)*c + a
else:
n = (y/z)*c + a
if n != math.fmod(x,lcm):
print (a,b,c,d,x)
print ("done")

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um, the * symbol for multiplication is making things italic

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how do I fix that

torn escarp
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put three ` before and after

jovial hemlock
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import math
for c in (3,100):
for d in (2,c-1):
lcm = (c * d/math.gcd(c,d))
for x in (0,lcm-1):
a = math.fmod(x,c)
b = math.fmod(x,d)
y = d - math.fmod(c,d)
z = math.fmod((a-b),d)
if z == 0:
n = 0
elif z > y:
n = (z/y) * c + a
else:
n = (y/z) * c + a
if n != math.fmod(x,lcm):
print (a,b,c,d,x)
print ("done")

torn escarp
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for i in range(1,100):
  print(i)
jovial hemlock
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oh did I forget the word range? is that all?

torn escarp
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I didn't look at your code I was just saying put three ` before and after to format your code

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and gave an example

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if your code is broken test individual pieces in smaller chunks rather than doing it all in one huge thing

jovial hemlock
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I did

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I got confused

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I made typos

sacred junco
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Solved it nvm

jovial hemlock
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new question

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apparently python interprets “fmod(-2,5)” to be -2

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when it should be 3

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how do I fix that

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k, I just add the 5 to the -2 until it’s above 0

torn escarp
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you can do mod instead of fmod

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I think that fixes it

alpine jasper
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i know that K is a k vector space but i'm not sure how to show K is finite dimensional

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i was thinking of finding a basis, but i have no idea how

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i can also try to argue that field containing finite dimensional fields are also finite dimensional, poor wording ik

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@winter bear help me papa

winter bear
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hmm gimme a sec i think i have a proof for this written somewhere

alpine jasper
winter bear
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i mean, the idea is to induct

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start of by removing one root, and then extend this new field by removing another

alpine jasper
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i'll give induction a shot

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okay i'm still not sure how

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i want to prove that $[k(\alpha_1):k]$ is finite right, and then keep adding on more $\alpha_i$ until it hit $\alpha_n$

winter bear
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kinda

sterile pumiceBOT
winter bear
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i mean basically

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lemme refine this for you a bit by giving you an inductive hypothesis

alpine jasper
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but i need that as a base case tho

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unless you're talking about a different induction

winter bear
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$P(n)$: for each poly in any field of degree $n$, theres a splitting field thats a finite degree extension of this field

sterile pumiceBOT
winter bear
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i mean this is kinda equivalent to your idea of "keep adding a_i"

alpine jasper
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tru

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i see

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let me give that a shot

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i'm still not sure where to complete the hypothesis

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the first line assumed f is degree 1

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and green marks the degree of f

winter bear
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i mean the idea is basically right? try to refine it, for example f(x)=x-a splits in k, no need to say k(a_1)

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also i think it would be nicer if you directly use prop 7.2.1

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but yeah idea is correct, you reduce the degree by finding a field for one of its roots, and then by induction that splits in a finite extension field

alpine jasper
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i sort of did by assuming those $K_{\alpha_i}$ exists?

sterile pumiceBOT
alpine jasper
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but i just don't see where to go with this induction

winter bear
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oh right ok so

alpine jasper
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oh wait

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g has degree less than n

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so it factors

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?

winter bear
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yeah

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but ill say, its nicer to consider just one root

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rather than all that i roots

alpine jasper
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i'm not sure how that works

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i factor out 1 root at a time?

winter bear
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basically

alpine jasper
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but induction tells me to assume it for arbitrary number of roots no..?

supple furnace
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Just remember that if K is contained in L, [K(a):K]>=[L(a):L]

winter bear
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i mean yeah idea still works i wont complain about the asthetics ig

alpine jasper
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hmm

supple furnace
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You probably also want to verify that adjoining elements maintains field structure

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Which can be done inductively as well

alpine jasper
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i see

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thanks john and tree3

alpine jasper
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okay i'm actually still stuck

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what am i doing wrong sad

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am i suppose to say deg f = i?

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my small brain just can't make sense of this

winter bear
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ok so lets say f has deg i+1 right

alpine jasper
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mhm

winter bear
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by prop 7.2.1 we can find a finite extension of this such that theres a root, i.e f(a)=0 right

alpine jasper
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yes

winter bear
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then do f(x)=(x-a)g(x)

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do you see what to do from here

alpine jasper
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g splits since it is degree i

winter bear
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mhm, specifically splits in a finite extension

alpine jasper
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right

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hmm, but what field does f splits then?

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is that field K + [field that g splits]

winter bear
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ok so we extended $k$ to lets say $K_a$, and then we extended $K_a$ to lets say $K_a'$, i.e where $g$ splits

sterile pumiceBOT
winter bear
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so where does f split here

alpine jasper
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the reason why the second extension from K_a to K'_a is finite is because degree of g is i?

winter bear
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yeah, by inductive hypothesis we can make a finite extension of g since its deg i

alpine jasper
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icic

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thank you dad

winter bear
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np son

sleek cove
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Is it bad that I didn't use the second property (ii) in the proof?

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wait, i need it for proving the first direction nvm

sleek cove
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is there a fast way to show that phi (n) = 2 is only true for n = 3,4,6

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nvm

alpine jasper
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so by euler's theorem, f = phi(n)

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i also note that i can factor out x-1 in x^n - 1

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but other than that, i'm pretty clueless

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hint pls

winter bear
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so first its not phi(n)

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the order itself can be smaller than phi(n)

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for example, 2^3=1 (7)

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and heres your hint

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$n|q^f-1$ which is also the order of the multiplicative group

sterile pumiceBOT
winter bear
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@alpine jasper

alpine jasper
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i'm not sure if this makes any sense

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i still don't see where i used (q, n) = 1

winter bear
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hmm i dont see how ker dividing |E^x| told u n|q^f-1

alpine jasper
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if G a group and H a subgroup, |H| | |G|? is that the lagrange theorem or somethin

winter bear
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yes but where did n come from

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that tells you ker(x^n-1) | q^f-1

alpine jasper
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kernel has size n since we're basically working with nth root of unity?

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i'm not entirely sure

winter bear
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oh yeah ok

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cause it splits it has n roots

alpine jasper
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uh huh

winter bear
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you couldnt find a splitting field in the first place if q|n btw

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is where this would fall apart

alpine jasper
winter bear
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for the (q,n)=1 condition

alpine jasper
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is unsolvable if (n, q) != 1?

winter bear
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also that

alpine jasper
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hmm my smol brain don't immediately see why

winter bear
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ill let u work it out

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but as to the bigger problem

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you have shown if $x^n-1$ splits in extension of degree $f$, then $n|q^f-1$ right.

sterile pumiceBOT
winter bear
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but unfortunately this doesnt tell you wether f is minal and when n is minal

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so what do you think you should do

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oof i mispelled minimal twice the same way

alpine jasper
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hmm yeh good point

winter bear
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think about it for a bit, its p similar to this to show the other part

alpine jasper
#

alright

#

ty

winter bear
#

np

alpine jasper
#

i think this shows that gcd must be 1 otherwise the eq. is unsolvable as expected

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but i'm stuck on how to argue the minimality of f

winter bear
#

yeah, btw what u did is basically euclids algorithim for gcd

alpine jasper
#

yeah i've noticed

winter bear
#

ok so remember what u showed b4

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try showing the converse

alpine jasper
#

that gcd=1 implies solvability?

winter bear
#

no the other one

#

the splits implies n|q^f-1

alpine jasper
#

i see

#

i'll give it a shot

#

ty

#

idk how

#

i also don't understand why splits iff n|q^f-1 implies f is minimal

winter bear
#

well remember when u solved x^n=1 in fields right

alpine jasper
#

uh huh

winter bear
#

how many solutions and what was the criterion for solving this

alpine jasper
#

n solutions, (n, q) = 1

winter bear
#

and what else

#

umm lemme phrase it like this

#

how many sols does $x^n=1$ have in $\mathbb{F}_{p^k}$

sterile pumiceBOT
winter bear
#

prolly look back in IR if you dont remember

alpine jasper
#

hmm

winter bear
#

wait (n,q) is tru nvm that

alpine jasper
#

either 1 or n?

winter bear
#

yeah, depending on what

alpine jasper
#

since either just trivial soln or a non trivial soln which generates the rest

#

umm

#

n | p^k - 1

winter bear
#

there you go

#

and if it has n solutions, what can you say about the poly x^n-1

alpine jasper
#

it splits

winter bear
#

yeah, so do you see how this works then

alpine jasper
#

not really

#

gimme 5 mins

winter bear
#

ok

alpine jasper
#

so if n|q^f-1, then x^n = 1 have n solutions in F_(p^f), so it splits in E?

winter bear
#

F_(q^f) but yeah

alpine jasper
#

am i suppose to write F_(q^k) instead?

winter bear
#

umm not really. theres only one field of each order so as long as its clear what the order is its fine

alpine jasper
#

hmm alright

#

i still don't understand why splits iff n|q^f-1 implies f is minimal tho

winter bear
#

well take the smallest f such that n|q^f-1

#

what happens if there is some f'<f

#

such that extension of that degree splits the poly

alpine jasper
#

n | f'?

#

or contradiction since such extension does not exist?

winter bear
#

contradiction basically

#

also n|f' is not true

alpine jasper
#

oh right that makes no sense i just realize

#

i should think about why that extension dne

winter bear
#

another way to look at this that extension degrees where this split is one-to-one corrospendence with f such that n|q^f-1

#

if that helps

alpine jasper
#

damn

#

i just don't see how this works

winter bear
#

thats ok

#

umm so

#

$f$ deg extension where $x^n-1$ splits $\iff$$n|q^f-1$. Take the smallest $f$ such that $n|q^f-1$, if there is a smaller degree extension $f'<f$ where $x^n-1$ splits, then we know $n|q^{f'}-1$, but this contradicts minimiality of $f$.

sterile pumiceBOT
alpine jasper
#

oh

#

i thought we can't assume f being minimal

winter bear
#

well it was kind of a contradiction right

alpine jasper
#

Take the smallest f such that n | q^f - 1
this is the important bit right

winter bear
#

yeah

#

this kind of corrospondence is called an order preserving corrospondence btw

alpine jasper
#

Take the smallest f such that n | q^f - 1

smaller extension that splits
implies
f is not the smallest

#

yeh.?

winter bear
#

yep

alpine jasper
#

ok i see

#

that works

#

do u mind reading a more elementary attempt that i had

winter bear
#

yeah sure

alpine jasper
#

uhh, so the idea is to reduce the degree that q is raised to all the way to 1

#

idk if that's a contradiction

#

probably pure garbage

winter bear
#

well so one thing is that u arent garunteed to get 1

#

just gcd(f,s)

#

in exponent

#

(think about why)

#

and hmm i mean this isnt a contradiction

#

you'd have to use the corrospondence we used above

#

i think

alpine jasper
#

yeah

#

i don't see how that works too

#

but i'm still not sure why the lowest is (f, s)

winter bear
#

hmm do you see it cannot be any lower than (f,s)

alpine jasper
#

i was thinking we can perform this lowering thing at most f times

#

i don't see

winter bear
#

ok so the exponent will end up as a combination of f and s right

#

and gcd divides both

alpine jasper
#

oh.

winter bear
#

to show its exactly gcd is a bit more slick

#

$q^f=1 (n)$, $q^s=1(n)$ then $q^{(f,s)}=1(n)$

sterile pumiceBOT
winter bear
#

ill give u a hint if u wanna prove this

#

(btw it can be lower than (f,s), but u wont get that number by just this info, is what i meant)

alpine jasper
#

i will leave this to another day

winter bear
#

i mean its a one liner

alpine jasper
#

i feel like i just have to write out the defn

winter bear
#

in a manner of speaking yes

#

if u define gcd by ||bezouts||

alpine jasper
#

hmm

#

still don't see it and i won't bother more

#

thanks for your help btw

winter bear
#

np

alpine jasper
#

hello

#

i'm once again asking for your nt support

#

is this the set i'm considering?\
${x\in\mathbb Z[i]\mid x\equiv p(p)}$

sterile pumiceBOT
alpine jasper
#

doesn't make much sense to me

#

this is the same as\
${x\in\mathbb Z[i]\mid p\text{ divides } x}$

sterile pumiceBOT
alpine jasper
#

or is the set something else..?

#

i suppose that set would make sense

#

it has
p + pi
2p + pi
...
p^2 + pi = 0 + pi
and for each kp + pi, i can "branch out" the imaginary component so like
kp + pi, kp + 2pi, ... kp + p^2 i = kp

#

for p^2 elements in total

#

that seems too easy or am i missing something again

light flicker
#

asking you to look at z[i]/(p) basically

alpine jasper
#

this is a quotient ring right

light flicker
#

yes

alpine jasper
#

ok i should try to formally write down what this means my algebra sucks

#

$\mathbb Z[i]/(p)={a+bi+x\mid x\in(p)}$

sterile pumiceBOT
alpine jasper
#

umm

#

is this right?

light flicker
#

yeah

alpine jasper
#

i'm not sure how to like, count it tho..

#

it looks like i can make the real part running from 1 to p

#

but do i have any control over b?

#

i'm being dumb again probably

alpine jasper
#

i still can't figure it out

#

help pls sadcat

light flicker
#

oops sorry

#

one way is to figure out when {a + bi + x} = {c + di + x}

alpine jasper
#

i'd say b = d(p) and a = c(p)

#

actually

#

.. yeah?

#

{a + bi + x} = {c + di + x}
by this do you mean

#

${a+bi+x\mid x\in(p)}={c+di+x\mid x\in(p)}$

light flicker
#

yes

sterile pumiceBOT
alpine jasper
#

so ok, only b = d(p) is needed

light flicker
#

are you sure? so {1 + x} and {2 + x} are the same set?

alpine jasper
#

is it a single x

#

or is the first set like... {1 + 1, 1 + (2), ..., 1 + (p-1)}

light flicker
#

Sorry, I'm just writing the shorthand

#

I mean {1 + x | x \in (p)}

#

but remember that (p) is an ideal in Z[i]

#

so it has elements like pi

#

er p * i

alpine jasper
#

oh wat

#

i thought its just 1, 2, ..., p-1

#

let me think about it

#

ok i don't understand why it'll have stuff like pi

light flicker
#

(p) is the ideal generated by p

alpine jasper
#

this means it contains (a+bi)p for any (a+bi) in Z[i]

#

right

light flicker
#

and only those

#

yes

alpine jasper
#

oh. i thought you meant pi as in 3.14...etc

#

my bad

light flicker
#

lmao

#

yeah

#

that's why I said

#

er p * i

alpine jasper
#

ok gud let's more forward

#

let me think about it for a sec

#

${1+x\mid x\in(p)}={1+p(a+bi)\mid a+bi\in\mathbb Z[i]}={(pa+1)+(pbi)\mid a,b\in\mathbb Z}$

sterile pumiceBOT
alpine jasper
#

are you sure? so {1 + x} and {2 + x} are the same set?
so no afterall, if {a + bi + x} = {c + di + x}, then b = d(p) and a = c(p)

light flicker
#

yeah

#

so can you list out the p^2 sets

alpine jasper
#

that is some gud shit

#

idk if this notation makes sense

#

to show that Z[i]/(p) is a field, should i try to show (p) is a maximal ideal or working with the RHS directly?

light flicker
#

the former's easier

alpine jasper
#

wops one small detail

#

i should add another pair of {}

#

ok, let me try that

alpine jasper
#

i hope this makes sense

alpine jasper
#

actually, why was the fact that p=3(4) never used? @light flicker

light flicker
#

q is an element of Z[i]

#

so its not immediately true that since q |p that q = 1

#

here is where you use the fact that p = 3(4)

#

if p = 1 (4), for example if you take p = 5, then its not true since 5 = (2 - i)(2 + i)

alpine jasper
#

woow damn that's beautiful

#

tyty

alpine jasper
#

welp

#

i tried computing the sum separately but no luck with the first one, and this is what i have so far for the second one

light flicker
#

have you seen the proof of the euler product for the zeta function

alpine jasper
#

this right, yes

#

but the form is not exactly right, for example, LHS has the base as n, but what i had above has it as p

#

i looked at it for a while and don't know how to apply it

light flicker
#

Sure, but

#

the f in the product and f in the sum are over different sets

alpine jasper
#

and that too

#

umm, so more complicated?

light flicker
#

It's the same idea

#

Look at the proof for the euler product for the zeta function

#

and adapt it

alpine jasper
#

hmm alright

#

so i looked at the proof

#

and the idea is that i multiply and remove stuff with factors systematically

#

sort of like treating monic poly as numbers, and monic irred poly as primes

#

but i'm stuggling to formualize and figure out what to multiple and subtract

#

bascially i don't see what's the analogous equivalent thing to 1/2^s

light flicker
#

Uh, I'm not sure what proof you looked at

#

But maybe I'll just say that

alpine jasper
light flicker
#

$\frac{1}{1 - p^{-s}} = 1 + \frac{1}{p^{-s}} + \frac{1}{p^{-2s}} + \cdots$

sterile pumiceBOT
light flicker
#

yeah, you should think of this fact as coming from the fundamental theorem of arithmetic

#

Basically if you take some number like 12

#

12 = 2^2 * 3

#

so to get 12, you'll multiply $\frac{1}{2^{-2s}} \cdot \frac{1}{3^{-s}} = \frac{1}{12^{-s}}$

sterile pumiceBOT
alpine jasper
#

ok i'll think about that

light flicker
#

It's kind of the intuitive idea why it works

#

So like the product is

#

$\left( 1 + \frac{1}{2^{-s}} + \frac{1}{2^{-2s}} + \cdots \right) \left( 1 + \frac{1}{3^{-s}} + \frac{1}{3^{-2s}} + \cdots \right) \left( 1 + \frac{1}{5^{-s}} + \frac{1}{5^{-2s}} + \cdots \right) \cdots$

sterile pumiceBOT
alpine jasper
#

ok gimme some time to digest that

light flicker
#

This is just rewriting the product

alpine jasper
#

uh yeah, but i don't know how to adapt this

light flicker
#

So the idea is that every positive integer can be uniquely written as the product of power of primes

#

Similarly, every monic polynomial can be unique written as the product of powers of irreducible monic polynomials

alpine jasper
#

god damn

#

i just don't see what to do really

#

i'm suppose to multiply this by something in terms of monic irreducible poly right

#

call this original sum S, then suppose after i multiply, i get AS, then i do S - AS, which equals to S - some stuff that are not irredicuble

#

that probably made no sense

light flicker
#

Idk, again

#

$\left(1 - \frac{1}{(Nf)^s} \right)^{-1} = \frac{1}{1 - (Nf)^{-s}} = \left(1 + \frac{1}{(Nf)^{-s}} + \frac{1}{(Nf)^{-2s}} + \cdots \right)$

sterile pumiceBOT
light flicker
#

idk, if you want to do it the way that wikipedia does it

#

Then yeah, take some irreducible monic polynomial g

#

And if you do what they do

#

you'll remove all the terms in the sum that were divisible by g

alpine jasper
#

idk where that second equality came from really

#

and yes i've been trying to do it analogous to the one from wiki with 0 progress

#

let me think about this more ig

light flicker
#

the second equality is just geometric series

alpine jasper
#

oh

#

i just don't think i can do it the way wiki did it

#

because the numerators

#

if i multiply everything by like, p/p^(2s) then do the same thing

#

the terms wouldn't like, line up

light flicker
#

where are those p's on top even coming on top

alpine jasper
#

i count by degree of f

#

but suppose degree f = 7, then i have x^7 + ax^6 + bx^5 + ...

#

oh wait did i counted it wrong

light flicker
#

no its right

#

but you don't need to write it like this

alpine jasper
#

there are p^6 choices of degree 7 monic poly

light flicker
#

and I'm not sure writing it like this will help you

alpine jasper
#

i turned it into this and that's not a nice form too

light flicker
#

$\zeta_R(s) = \sum_{f \in R, f \text{ monic}} \frac{1}{(Nf)^s}$

sterile pumiceBOT
light flicker
#

then take some irreducible monic polynomial g

#

you have that $\frac{1}{(Ng)^s} \zeta_R(s) = \sum_{f \in R, f \text{ monic}} \frac{1}{(Nfg)^s}$

#

Since $(Nf)^s (Ng)^s = (Nfg)^s $

sterile pumiceBOT
alpine jasper
#

ok let me see if i can continue

#

ok i think i can finish it

#

just to make sure, 1 is not a monic irreducible polynomial by definition right? since it can't be factored into two non-constant poly

light flicker
#

yeah

#

irreducibles have to be not units

#

they have to be non-invertible

alpine jasper
#

i see

light flicker
#

This is by definition

alpine jasper
#

thanks for your immense amount of patience my dude

light flicker
#

You're lucky I've been grading and have nothing better to do

alpine jasper
#

lmao

alpine jasper
#

i'm stuck once again sadcat

#

i completed 2 successfully but 3 is giving me a hard time

#

@light flicker

alpine jasper
#

<@&286206848099549185>

alpine jasper
#

ok i figured it out, i was digging the wrong rabbit hole smh

alpine jasper
#

@winter bear hey dad i'm online now

#

are you availableflonshed

winter bear
#

yeah im online now

supple furnace
#

Me too

winter bear
#

@alpine jasper

alpine jasper
#

noice

winter bear
#

oof

alpine jasper
#

do you want me to repost the problem again

winter bear
#

yeah

supple furnace
#

Did you figure it out

alpine jasper
#

no i did not

winter bear
#

wait ill let tree3 help u out here, cause i kinda have some hw to do

alpine jasper
#

ok nice

#

N(n) is the number of monic irreducible polynomial in Z/pZ[x] where p is a prime

supple furnace
#

log(1-x) taylor series

alpine jasper
#

i did exactly that actually

#

didn't really work, let me post my work

supple furnace
#

You want to compare coefficients: the 1/p^(ks) coefficients should match up for each k.

alpine jasper
#

let me try again i guess, i'm less tired than yesterday

#

mostly stuff written in blue

supple furnace
#

Yeah

#

Start by finding the 1/p^(ns) coefficients of both sides

#

Do LHS and RHS individually

alpine jasper
#

gimme a moment i'll report back

#

so this is precisely where i'm stuck

#

i don't know how to deal with 1 sum on the LHS and 2 sum on the RHS

#

i tried to write it in form of\
$\sum_{\beta\geq1}\sum_{n\geq1}(\textit{stuff})$

sterile pumiceBOT
supple furnace
#

We want to find the coefficient of 1/p^(ns)

#

Which acts like an x^n coefficient for x=p^s

#

In -log(1-p^(1-s)), we get (p^(1-s))^n/n

#

=p^n/n(p^(-ns))

#

So the coefficient is p^n/n

alpine jasper
#

let me digest that

#

gimme a moment

#

In $-\log(1-p^{1-s})$, we get $(p^{1-s})^{n/n}=\frac{p^n}{n(p^{-ns})}$

sterile pumiceBOT
alpine jasper
#

umm i'm just texing it so easier to read

#

hmm

supple furnace
#

In $-\log(1-p^{1-s})$, we get $\frac{(p^{1-s})^n}{n}=\frac{p^n}{n}(p^{-ns})$

sterile pumiceBOT
supple furnace
#

This is just from the Taylor series expansion

alpine jasper
#

yeh gimme a moment

#

so stuff in purple must match?

supple furnace
#

Um no because the stuff circled in purple can’t have an s in it

alpine jasper
#

idk how to manipulate the RHS really :/

#

i also dont get the idea of matching terms, since i can have two different series summing to the same thing but the nth term need not be the same right?

supple furnace
#

On the RHS, we have terms in the form $-N(k)\log(1-p^{-ks})$, which when expanded give terms in the form $\frac{N(k)p^{-krs}}{r}}$. We just need to identify which of these terms correspond to $p^{-ns}$. This occurs if and only if $kr=n$, so to account for all possibilities, we just select $k$ to be any divisor of $n$ and $r$ to be $\frac{n}{k}$. This gives terms of the form $\frac{N(k)p^{-ns}}{\frac{n}{k}}=\frac{kN(k)p^{-ns}}{n}$, where $k$ ranges over the divisors of $n$. Summing these and comparing coefficients gives the result.

sterile pumiceBOT
alpine jasper
#

is this what you mean?

supple furnace
#

Um you lost a sum

#

We’re just extracting coefficients

alpine jasper
#

i don't think i'm getting the idea here

#

let me reread what you said above

#

so like this...?

#

i'm a big dumb

#

bc i'm only looking for coefficient of p^(-ns)

supple furnace
#

It should still be a double sum

alpine jasper
#

i don't know what i'm summing over when i write kr=n

supple furnace
#

Divisors of n

alpine jasper
#

i know that, i mean like, where i should put my second sum

supple furnace
#

Inner sum is over k|n

#

Outer sum is n>=1

alpine jasper
#

okay this must be it

supple furnace
#

There you go

alpine jasper
#

so removing the 1/n term gives us the result

supple furnace
#

Yes

alpine jasper
#

i don't fully understand how you turn the sum into that form, let me think about it more

#

thanks btw

supple furnace
#

The idea is that you want to find all terms corresponding to p^(-ns), so you set kr=n and solve for r in terms of k.

#

The new constraint is just k|n because k can be any divisor of n

alpine jasper
#

ok i think i get it now

#

thanks

supple furnace
#

Np

sleek cove
sleek cove
#

i literally cant find anything saying that (p/q) = (q/p) PepoG

#

wait sry im dumb

karmic edge
#

Let p be an odd prime. Use Theorem 7.5 to prove that there is exactly one positive primitive
Pythagorean triple (x, y, z) with y = p, and find formulas for x and z in terms of p.

#

Theorem 7.5.
If (x;y;z) is a primitive Pythagorean triple, where x is even and x, y, and z are positive, then x= 2st; y=s2-t2; and z=s2+t2; for some relatively prime positive integers s and t. Conversely, if s and t are relatively prime, s > t >0, and s or t is even, then (2st; s2-t2; s2+t2) is a primitive Pythagorean triple.

#

I'm having some difficulty with how to go about this proof. I set y=p=s^2-t^2 but I see no way to write x and z in terms of just p.

light flicker
#

Think about factoring s² - t²

karmic edge
#

Right, so p = (s-t)(s+t). Ohhhh -- but p is prime! So s-t = 1.

#

I did that earlier and i don't know how i missed that lol

#

Thank you! I got it now

obtuse mason
#

let a be in N and p be a primefactor of n = (2a)^2 + 1

#

show p is congruent 1 modulo 4

#

I can eliminate 2 because (2a)^2 + 1 is uneven so 2 can't be a prime factor

#

but don't get much farther than that

upbeat wren
#

is n an element of N?

#

(in the problem)

light flicker
#

@obtuse mason p dividing (2a)^2 + 1 means that (2a)^2 + 1 is 0 mod p

#

Then think about quadratic residue things

obtuse mason
#

oh

#

@light flicker thank you so much 🙂

dreamy rain
#

for this to be true, u and v would have to be non-integer?

#

because g is smaller than both u and v

fervent crest
#

No

#

u and v can be negative

#

That’s the whole point

#

@dreamy rain

dreamy rain
#

oh are they using bezouts identity?

#

if so thats strange since bezouts hasnt been covered in the book yet

#

but thatd make the most sense yea

fervent crest
#

Lmao yes

#

It's the bezout's identity

torn escarp
#

,calc xgcd(13,17)

sterile pumiceBOT
#

Result:

[1, 4, -3]
fervent crest
#

,calc 413-173

sterile pumiceBOT
#

Result:

1
stuck lintel
#

Determine all positive integers $n$ such that $n^2$ divides $2^n+1$.

sterile pumiceBOT
winter bear
#

consider the ||2 smallest prime factors of n||

stuck lintel
#

hmm

sacred junco
#

That's an imo p3 lel

stuck lintel
#

really?

sacred junco
#

Yes

winter bear
#

yeah lol

stuck lintel
#

its part of the amsp N2 pset bruh

winter bear
#

i solved this b4

#

which is why i managed to give u a hint in a second lol

stuck lintel
#

can u give me another hint lol

winter bear
#

umm ok start by considering smallest possible prime factor p of n

#

what can you deduce about p from this

sacred junco
#

Are you doing awesome math?

stuck lintel
#

no the deadline passed but im trying some sample problems for fun

#

hm yeah im not sure

winter bear
#

ok try arguing on order

winter bear
#

so first definations

sterile pumiceBOT
stuck lintel
#

o lord

sterile pumiceBOT
winter bear
#

yeah try doing these to also absorb the defination

#

tell me when you are done

stuck lintel
#

wait (n/d) is the legendre symbol right?

winter bear
#

oh no its just division lol

stuck lintel
#

oh 🤦‍♂️

#

oh its associative commutative since ${ d | d\text{ divides }n}$ is the same as ${n/d | d\text{ divides }n}$

winter bear
#

commutative* but yes

sterile pumiceBOT
supple furnace
#

The sol to n^2|2^n+1 is very short tbh

stuck lintel
#

can u give a solution sketch?

#

also im not sure why its associative john

supple furnace
#

For associativity, think about convolution as sum ab=n f(a)g(b)

winter bear
#

yeah^

supple furnace
#

||Clearly n=1 works. Suppose n>1 and let p be the least prime factor of n. Then p|2^n+1 and so p|2^(2n)-1. Therefore p|2^(gcd(2n),p-1))-1. p-1 must be relatively prime to n since it is less than each prime factor of n, so p|2^2-1=3. Hence n=3k. If k=1, then n=3 works. Now suppose k>1 and let q be the least prime factor of k. We have q|2^(3k)+1 and so q|2^6-1 for similar reasons. 2^a+1 is never divisible by 7, so q=3 again. However, since n is odd, 1+v_3(n)=v_3(2^n+1)>=2v_3(n), contradiction for v_3(n)>1.||

winter bear
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progress plum?

stuck lintel
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i think i have an idea

supple furnace
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John was anything different in your sol

winter bear
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i think it was p much exactly the same, with minor divergences in the end

supple furnace
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Forgot to say n is odd before lte oops

winter bear
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right my order of logic was a bit different then urs, but ultimately same thing ||i said power of 3 must be 1 before doing the 2nd smallest prime factor||

leaden compass
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yeah my sol was the same as yours john iirc

supple furnace
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I like getting contradictions lol

stuck lintel
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$f * (gh) = \sum_{ab = n} f(a)(gh)(b) = \sum_{ab=n} f(a) \sum_{cd=b} g(c)h(d) = \sum_{acd = n} f(a) g(c) h(d) = \sum_{ed = n} \sum_{ac = e} (fg)(e) h(d) = (fg)*h$

sacred junco
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Tree is anti constructivist

sterile pumiceBOT
supple furnace
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Yeah nice

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@stuck lintel

stuck lintel
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hold on i need to work on my hw but ill brb

leaden compass
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Personally I prefer intuitionist proofs

By this I do not mean following intuitionist logic, but rather by saying "intuitively it seems true, qed"

winter bear
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alright we'll continue it after u return

supple furnace
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Anyone have any problems

leaden compass
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Yeah

sacred junco
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What's 2+2

leaden compass
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My problem is I have overdue homework

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i do actually have one though

winter bear
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show spectrum of a ring is disconnected iff it contains a non-trivial idempotent

leaden compass
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a) Find a nice way of writing 1 + 2x + ... + (n+1)x^n

b) Find a nice way of writing 1 + 3x + ... + T_(n+1)x^n

c) Find a nice way of writing 1 + (T^k)_2 + ... + (T^k)_(n+1)x^n

Where (T^k)_n is the n-th k-th order triangular number (the sum of the 1st n (k-1)th order triangular numbers)

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(for example (T^2)_3 = T_1 + T_2 + T_3 = 1 + 1 + 2 + 1 + 2 + 3

supple furnace
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By Hockey stick this reduces to 1/k! times some kth derivative

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Is that considered “nice”

leaden compass
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Hint: (this idea applies to all of them so be careful before deciding to read) ||let's look at a: denote the sum by S, S - Sx = -(n+1)x^(n+1) + x^n + ... + x + 1 = (n+1)x^(n+1) + (x^(n+1) - 1)/(x-1) and so forth||

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Not sure what you mean tree

winter bear
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ew lol

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derivative is much better

supple furnace
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How is this “nice”

leaden compass
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Nice enough

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Care to explain the other method?

stuck lintel
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Just use finite differences for all of them

leaden compass
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Don't know that

winter bear
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$$f(x)=\dfrac{1}{1-x} = \sum x^n$$ $$f^{(k)}(x) = \sum n(n-1)\dots (n-k+1) x^{n-k}$$ $$\dfrac{x^k}{k!} f^{(k)}(x) = \sum \binom{n}{k} x^n$$

leaden compass
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Can you illustrate it

sterile pumiceBOT
winter bear
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i assume he meant

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oh plum you are back

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ready for some more?

stuck lintel
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im procrastinating xdd

winter bear
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oh oof

stuck lintel
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i think ill be finished at around 9 est if ur available then

supple furnace
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T^k(n)=(n+k+1)C(k+1)

winter bear
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oh oops, i mean same logic tho

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i prolly will plum

supple furnace
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1/(k+1)!(d^(k+1)/dx^(k+1)((x^(n+k+1)-1)/(x-1)))

leaden compass
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Now find all integral solutions to $n^420 - 1 | 420^n - 1$

sterile pumiceBOT
supple furnace
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My formula’s fairly succinct and leads to a closed form with number of terms independent of n by product rule expansion.

jovial hemlock
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Is there a way for me to prove that if A and B are coprime, then there is a k in 0 to (B-1) such that kA = X mod B for any arbitrary X in 0, B-1?

stuck lintel
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do you know how to prove that the multiplicative inverse to A exists given (A,B)=1?

jovial hemlock
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um

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I’m not sure off the top of my head from an analytical level, but I can easily take your word for it

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I can take that as a granted in what I need this for

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Actually, is the thing I said I needed to prove enough of an established fact that I can use it in a proof of something else without having to prove it first?

fervent crest
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Yes

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But it really depends on what you are doing

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If you're taking a number theory course, then your professor probably wants you to prove it

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But if you're talking to people who know even a little number theory, then they know this fact

jovial hemlock
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No, not a course

winter bear
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i mean ig proving this needs ||bezouts|| and the only proofs i know for that use WOP

fervent crest
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Or || use Euclidean algorithm and argue backward ||

jovial hemlock
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Okay second year ion

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question*

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if you have a prime A, and the next prime is B, is B guaranteed to be less than 2A? I’m pretty sure it is

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but I don’t know for sure if it’s been proven

winter bear
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yes, its proven theres always a prime between p and 2p

brittle patrol
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It's called Bertrand's Postulate

jovial hemlock
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okay good

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I think... I think I’m lined up really well

winter bear
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its very high powered though, compared to what you are doing

jovial hemlock
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I don’t think so

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it’s more of a case of I cba to try proving those right now as I don’t want to get distracted from what I’m doing overall and lose my train of thought

brittle patrol
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BTW an elementary proof that multiplicative inverses exist can be done by ||showing that no two elements in {0, a, 2a, ... , (b-1)a} give the same residue mod b||

jovial hemlock
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“I don’t think so” was bad phrasing and arrogant, sorry

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it was more “I’m not sure”

winter bear
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oh thats smart gonzo

jovial hemlock
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Gonzo, showing that no two elements have the same residue mod B is what I wanted to know if it was proven lol

brittle patrol
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Yeah, but formulating it like that is like half the solution

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think about what if ax=ay mod b

remote sinew
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Quick question.

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I'm not sure I understand why, about 2/3 of the way down, each of a,b,c must be even.

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Why couldn't, say, a be even and b,c be odd?

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...is it because then you'd end up with a number congruent to 2 mod 4?

light flicker
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Yes

remote sinew
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K.

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I realized that as soon as I posted it :P

fervent crest
sacred junco
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lmao

exotic scarab
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did i do smthn

sacred junco
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What

jovial hemlock
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so

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I don’t want to sound stupid or like a crank here

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I have in front of me what I believe to be a proof of the twin prime conjecture. I am also fairly certain that such a proof must be wrong because of how long people looked for one and didn’t find one, but I personally can not find any errors in it. Where can I put it to have someone look over it and see if/where there are error?

light flicker
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right here

jovial hemlock
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like just type it out in the channel?

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it’s a couple pages long in my word doc, is that okay?

stoic bear
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Link it or upload

jovial hemlock
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Um okay let me open discord on my computer

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I'm sorry it isn't written formally I don't know how to do that

light flicker
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should probably remove your name from the doucment

jovial hemlock
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oops

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In the third line I refer to L- this is a typo it should be O in that line

light flicker
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I don't see how your earlier analysis, which seems correct to me, applies to the situation with Q, C and R

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Earlier, when you were assuming you had a pair of twin primes, there was exactly one number N inbetween the twin primes

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but here, there is no single number between Q and R, so you can't really apply your earlier analysis

jovial hemlock
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The earlier analysis describes the property a number must have, the Q/C/R bit is about proving a number with those properties exists

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Q and R aren't twin primes, they're the primes that are the equivalent of A and B in the earlier analysis

light flicker
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Then, I guess I'm confused what the "list of last digits" is

jovial hemlock
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like

light flicker
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the last digits of what number

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earlier, it was the possible last digits of N, but now there's no N

jovial hemlock
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well there is an N

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what you're doing is you're saying "If an N exists, it must have these properties; and if these properties are satisfied on a number then that number is an N"

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and so the list for Q is saying "If an N exists, it must have one of these last digits when written in base C"

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and obviously you can't immediately say "if these properties are satisfied on a number then that number is N" because the N could be 1 mod a prime above Q but below sqrt(N), which is what the section about G and F is dedicated to showing that a number has to exist without that problem

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the list of last digits is basically saying "N = Y mod C" and the list is all possible values of Y

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I'm just using the last digits phrasing because it's more intuitive to my brain so by using this phrasing I could avoid confusing myself when writing it up

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what may help you is G is the equivalent of N

light flicker
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Okay, I'm also confused because, you're not assuming such a G exists, you're trying to show that such a G exists right

jovial hemlock
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right

light flicker
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Then how can you let F be the largest prime below G - 1, if you don't know if G exists yet?