Metamath Proof Explorer

Theorem ensymb

Description: Symmetry of equinumerosity. Theorem 2 of Suppes p. 92. (Contributed by Mario Carneiro, 26-Apr-2015)

Ref Expression
Assertion ensymb A B B A


Step Hyp Ref Expression
1 ener Er V
2 1 a1i Er V
3 2 ersymb A B B A
4 3 mptru A B B A