Axiom ax-frege58a 38169

Description: If A. x ph is affirmed, [ y / x ] ph cannot be denied. Identical to stdpc4 2353. Axiom 58 of [Frege1879] p. 51. (Contributed by RP, 28-Mar-2020.) (New usage is discouraged.)

Assertion

Ref	Expression
ax-frege58a	|- ( ( ps /\ ch ) -> if- ( ph , ps , ch ) )

Detailed syntax breakdown of Axiom ax-frege58a

Step	Hyp	Ref	Expression
1		wps	. . 3 wff ps
2		wch	. . 3 wff ch
3	1, 2	wa 384	. 2 wff ( ps /\ ch )
4		wph	. . 3 wff ph
5	4, 1, 2	wif 1012	. 2 wff if- ( ph , ps , ch )
6	3, 5	wi 4	1 wff ( ( ps /\ ch ) -> if- ( ph , ps , ch ) )

This axiom is referenced by:  frege58acor  38170  frege61a  38173  frege67a  38179