Theorem r19.37av 1300

Description: Restricted version of one direction of Theorem 19.37 of [Margaris] p. 90. (The other direction doesn't hold when A is empty.)

Assertion

Ref	Expression
r19.37av	|- (E.x e. A (ph -> ps) -> (ph -> E.x e. A ps))

Distinct variable group(s):   ph,x

Proof of Theorem r19.37av

Step	Hyp	Ref	Expression
1		r19.35 1298	. 2 |- (E.x e. A (ph -> ps) <-> (A.x e. A ph -> E.x e. A ps))
2		ax-1 3	. . . 4 |- (ph -> (x e. A -> ph))
3	2	r19.21aiv 1259	. . 3 |- (ph -> A.x e. A ph)
4	3	syl4 19	. 2 |- ((A.x e. A ph -> E.x e. A ps) -> (ph -> E.x e. A ps))
5	1, 4	sylbi 174	1 |- (E.x e. A (ph -> ps) -> (ph -> E.x e. A ps))

Syntax hints:   -> wi 2   e. wcel 1092  A.wral 1201  E.wrex 1202

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6  ax-4 673  ax-5 674  ax-gen 677  ax-17 925

This theorem depends on definitions:  df-bi 128  df-or 197  df-an 198  df-ex 679  df-ral 1205  df-rex 1206

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