Theorem pm2.53 712

Description: Theorem *2.53 of [WhiteheadRussell] p. 107. This holds intuitionistically, although its converse does not (see pm2.54dc 881). (Contributed by NM, 3-Jan-2005.) (Revised by NM, 31-Jan-2015.)

Assertion

Ref	Expression
pm2.53	|- ( ( ph \/ ps ) -> ( -. ph -> ps ) )

Proof of Theorem pm2.53

Step	Hyp	Ref	Expression
1		pm2.24 611	. 2 |- ( ph -> ( -. ph -> ps ) )
2		ax-1 6	. 2 |- ( ps -> ( -. ph -> ps ) )
3	1, 2	jaoi 706	1 |- ( ( ph \/ ps ) -> ( -. ph -> ps ) )

Syntax hints:   -. wn 3   -> wi 4   \/ wo 698

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 605  ax-io 699

This theorem depends on definitions:  df-bi 116

This theorem is referenced by:  ori  713  ord  714  orel1  715  pm2.63  790  notnotrdc  833  dfordc  882  pm5.6r  917  xorbin  1374  19.33b2  1617  r19.30dc  2613  onsucelsucexmid  4507  oprabidlem  5873  omnimkv  7120  xnn0nnn0pnf  9190  absle  11031