Theorem dfifp2 1014

Description: Alternate definition of the conditional operator for propositions. The value of if- ( ph , ps , ch ) is "if ph then ps, and if not ph then ch." This is the definition used in Section II.24 of [Church] p. 129 (Definition D12 page 132) (see comment of df-ifp 1013). (Contributed by BJ, 22-Jun-2019.)

Assertion

Ref	Expression
dfifp2	|- (if- ( ph , ps , ch ) <-> ( ( ph -> ps ) /\ ( -. ph -> ch ) ) )

Proof of Theorem dfifp2

Step	Hyp	Ref	Expression
1		df-ifp 1013	. 2 |- (if- ( ph , ps , ch ) <-> ( ( ph /\ ps ) \/ ( -. ph /\ ch ) ) )
2		cases2 993	. 2 |- ( ( ( ph /\ ps ) \/ ( -. ph /\ ch ) ) <-> ( ( ph -> ps ) /\ ( -. ph -> ch ) ) )
3	1, 2	bitri 264	1 |- (if- ( ph , ps , ch ) <-> ( ( ph -> ps ) /\ ( -. ph -> ch ) ) )

Syntax hints:   -. wn 3   -> wi 4   <-> wb 196   \/ wo 383   /\ wa 384  if-wif 1012

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-ifp 1013

This theorem is referenced by:  dfifp3  1015  dfifp5  1017  ifpn  1022  ifpimpda  1028  ifpbi2  37811  ifpbi3  37812  ifpbi23  37817  ifpbi1  37822  ifpbi12  37833  ifpbi13  37834  ifpbi123  37835  ifpimimb  37849  ifpororb  37850  ifpbibib  37855  frege54cor0a  38157