Is reverse “induction” a valid proof method?

[mystic kelp]

I see no reason why would this not be true.
Suppose that

1. $P(0)$ is true.
2. If $P(k)$ is true, then $P(k-1)$ is true for $k ≤ 0, \in \mathbb{Z} $.
   Therefore, $P(n)$ is true for all $n \in \mathbb{Z}$ s.t. $n ≤ 0$.

[lucid sparrow]

k >= 1*

[modest cape]

number theorist
Compile Error! Click the reaction for more information.
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[mystic kelp]

wow what a quick response

I don't normally expect quick responses

[lucid sparrow]

Oh, I thought he wanted to pick e.g. k = 10, then go back to 0

[lucid sparrow]

Usually, the help channels (like #help-9 ) are more active than the forum

[mystic kelp]

Should i ask number theory proof questions here, in #elementary-number-theory or the help channels?

[lucid sparrow]

The help forum is basically equivalent to the help channels

I'd say the help channels are sometimes more active than #elementary-number-theory and you should be allowed to ask in both, so I'd go with the channels

[mystic kelp]

ok thanks

[mystic kelp]

.close