Theorem 19.20dvv 948

Description: Deduction from Theorem 19.22 of [Margaris] p. 90.

Hypothesis

Ref	Expression
19.20dvv.1	|- (ph -> (ps -> ch))

Assertion

Ref	Expression
19.20dvv	|- (ph -> (A.xA.yps -> A.xA.ych))

Distinct variable group(s):   ph,x   ph,y

Proof of Theorem 19.20dvv

Step	Hyp	Ref	Expression
1		19.20dvv.1	. . 3 |- (ph -> (ps -> ch))
2	1	19.20dv 946	. 2 |- (ph -> (A.yps -> A.ych))
3	2	19.20dv 946	1 |- (ph -> (A.xA.yps -> A.xA.ych))

Syntax hints:   -> wi 2  A.wal 672

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

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