Theorem pm2.65i 639

Description: Inference for proof by contradiction. (Contributed by NM, 18-May-1994.) (Proof shortened by Wolf Lammen, 11-Sep-2013.)

Hypotheses

Ref	Expression
pm2.65i.1	|- ( ph -> ps )
pm2.65i.2	|- ( ph -> -. ps )

Assertion

Ref	Expression
pm2.65i	|- -. ph

Proof of Theorem pm2.65i

Step	Hyp	Ref	Expression
1		pm2.65i.2	. . 3 |- ( ph -> -. ps )
2		pm2.65i.1	. . 3 |- ( ph -> ps )
3	1, 2	nsyl3 626	. 2 |- ( ph -> -. ph )
4		pm2.01 616	. 2 |- ( ( ph -> -. ph ) -> -. ph )
5	3, 4	ax-mp 5	1 |- -. ph

Syntax hints:   -. wn 3   -> wi 4

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-in1 614  ax-in2 615

This theorem is referenced by:  mt2  640  mto  662  pm5.19  706  noel  3426  0nelop  4248  elirr  4540  en2lp  4553  soirri  5023  canth  5828  0neqopab  5919  fzp1disj  10079  fzonel  10159  fzouzdisj  10179  lgsval2lem  14381  bj-imnimnn  14460  nnnotnotr  14712