15317 Constructive Logic
Recitation 4: Arithmetic
Today's recitation focused on learning how to use Tutch to reason about
natural numbers. We defined addition by structural recursion over its
first argument and proved that adding anything to zero yields that same
thing.
val plus : nat > nat > nat
proof plusN0N : !n:nat. plus n 0 = n
While proving this property of equality, we learned that Tutch employs a
few somewhat subtle principles to generate proofs of equality. They are
described in the handout for Assignment 3.
References:
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Frank Pfenning
