Theorem pm10.53

Description: Theorem *10.53 in WhiteheadRussell p. 155. (Contributed by Andrew Salmon, 24-May-2011)

	Ref	Expression
Assertion	pm10.53	|- ( -. E. x ph -> A. x ( ph -> ps ) )

Proof

Step	Hyp	Ref	Expression
1		pm2.21	|- ( -. E. x ph -> ( E. x ph -> A. x ps ) )
2		19.38	|- ( ( E. x ph -> A. x ps ) -> A. x ( ph -> ps ) )
3	1 2	syl	|- ( -. E. x ph -> A. x ( ph -> ps ) )