#negation
6 messages · Page 1 of 1 (latest)
I'm not sure if this is what others do, but I tend to have "such that" be implicit after every ∃
So, in this case, I'd write
¬∀a ∈ ℤ, (∃ b ∈ ℕ, {such that} 3a+b≠5)
≡
∃a ∈ ℤ, {such that} (∀b ∈ ℕ, 3a+b=5)
I'm not sure if this is the norm though
I find that saying it outloud helps too.
For every element x in the set of natural numbers such that P(x), ... Is equivalent to ∀x ∈ {n ∈ ℕ | P(n)}, ..., And not ∀ x ∈ ℕ, P(x). So, in this case, it wouldn't make sense for there to be a "such that" after the quantifier bit
Thank you so much
@topaz kestrelIf you want to, you can treat "such that" as an extra condition you are setting for a certain variable