Theorem a1i13 24

Description: Add two antecedents to a wff. (Contributed by Jeff Hankins, 4-Aug-2009.)

Hypothesis

Ref	Expression
a1i13.1	|- ( ps -> th )

Assertion

Ref	Expression
a1i13	|- ( ph -> ( ps -> ( ch -> th ) ) )

Proof of Theorem a1i13

Step	Hyp	Ref	Expression
1		a1i13.1	. . 3 |- ( ps -> th )
2	1	a1d 22	. 2 |- ( ps -> ( ch -> th ) )
3	2	a1i 9	1 |- ( ph -> ( ps -> ( ch -> th ) ) )

Syntax hints:   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7

This theorem is referenced by:  xpfi  6895  seq3fveq2  10404  seq3shft2  10408  seq3split  10414