Theorem pm5.71dc 956

Description: Decidable proposition version of theorem *5.71 of [WhiteheadRussell] p. 125. (Contributed by Roy F. Longton, 23-Jun-2005.) (Modified for decidability by Jim Kingdon, 19-Apr-2018.)

Assertion

Ref	Expression
pm5.71dc	|- (DECID ps -> ( ( ps -> -. ch ) -> ( ( ( ph \/ ps ) /\ ch ) <-> ( ph /\ ch ) ) ) )

Proof of Theorem pm5.71dc

Step	Hyp	Ref	Expression
1		orel2 721	. . . . 5 |- ( -. ps -> ( ( ph \/ ps ) -> ph ) )
2		orc 707	. . . . 5 |- ( ph -> ( ph \/ ps ) )
3	1, 2	impbid1 141	. . . 4 |- ( -. ps -> ( ( ph \/ ps ) <-> ph ) )
4	3	anbi1d 462	. . 3 |- ( -. ps -> ( ( ( ph \/ ps ) /\ ch ) <-> ( ph /\ ch ) ) )
5	4	a1i 9	. 2 |- (DECID ps -> ( -. ps -> ( ( ( ph \/ ps ) /\ ch ) <-> ( ph /\ ch ) ) ) )
6		pm2.21 612	. . 3 |- ( -. ch -> ( ch -> ( ( ph \/ ps ) <-> ph ) ) )
7	6	pm5.32rd 448	. 2 |- ( -. ch -> ( ( ( ph \/ ps ) /\ ch ) <-> ( ph /\ ch ) ) )
8	5, 7	jadc 858	1 |- (DECID ps -> ( ( ps -> -. ch ) -> ( ( ( ph \/ ps ) /\ ch ) <-> ( ph /\ ch ) ) ) )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 103   <-> wb 104   \/ wo 703  DECID wdc 829

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in2 610  ax-io 704

This theorem depends on definitions:  df-bi 116  df-dc 830

This theorem is referenced by: (None)