Theorem pm10.42

Description: Theorem *10.42 in WhiteheadRussell p. 155. (Contributed by Andrew Salmon, 17-Jun-2011)

	Ref	Expression
Assertion	pm10.42	|- ( ( E. x ph \/ E. x ps ) <-> E. x ( ph \/ ps ) )

Proof

Step	Hyp	Ref	Expression
1		19.43	|- ( E. x ( ph \/ ps ) <-> ( E. x ph \/ E. x ps ) )
2	1	bicomi	|- ( ( E. x ph \/ E. x ps ) <-> E. x ( ph \/ ps ) )