Theorem ensym

Description: Symmetry of equinumerosity. Theorem 2 of Suppes p. 92. (Contributed by NM, 26-Oct-2003) (Revised by Mario Carneiro, 26-Apr-2015)

	Ref	Expression
Assertion	ensym	$$⊢A\approx B\to B\approx A$$

Proof

Step	Hyp	Ref	Expression
1		ensymb	$$⊢A\approx B\leftrightarrow B\approx A$$
2	1	biimpi	$$⊢A\approx B\to B\approx A$$