/sci/ - Science & Math

>>10855613
I gave you both.

"For all x, the let y be x, and then reflectivity of equality tells us x=y, which reduces to x=x, is true."

Look at pic related: We need a proof of the [existence] [forall] x, and that proof of forall is an assignment and the proof of existence is a pair.
So given x, the pair holding y:=x and the (here, effectively via axiom) proof of x=y is the proof of
"Forall x, there exists a y such that x=y"