3
Parameter E : nat -> nat -> Prop.
4
Axiom E_equiv : equiv nat E.
6
reflexivity proved by (proj1 E_equiv)
7
symmetry proved by (proj2 (proj2 E_equiv))
8
transitivity proved by (proj1 (proj2 E_equiv))
10
Notation "x == y" := (E x y) (at level 70, no associativity).
11
Axiom r : False -> 0 == 1.