Theorem 2exim

Description: Theorem *11.34 in WhiteheadRussell p. 162. Theorem 19.22 of Margaris p. 90 with 2 quantifiers. (Contributed by Andrew Salmon, 24-May-2011)

	Ref	Expression
Assertion	2exim	|- ( A. x A. y ( ph -> ps ) -> ( E. x E. y ph -> E. x E. y ps ) )

Proof

Step	Hyp	Ref	Expression
1		exim	|- ( A. y ( ph -> ps ) -> ( E. y ph -> E. y ps ) )
2	1	aleximi	|- ( A. x A. y ( ph -> ps ) -> ( E. x E. y ph -> E. x E. y ps ) )