Theorem mt2 200

Description: A rule similar to modus tollens. Inference associated with con2i 139. (Contributed by NM, 19-Aug-1993.) (Proof shortened by Wolf Lammen, 10-Sep-2013.)

Hypotheses

Ref	Expression
mt2.1	⊢ 𝜓
mt2.2	⊢ (𝜑 → ¬ 𝜓)

Assertion

Ref	Expression
mt2	⊢ ¬ 𝜑

Proof of Theorem mt2

Step	Hyp	Ref	Expression
1		mt2.1	. . 3 ⊢ 𝜓
2	1	a1i 11	. 2 ⊢ (𝜑 → 𝜓)
3		mt2.2	. 2 ⊢ (𝜑 → ¬ 𝜓)
4	2, 3	pm2.65i 194	1 ⊢ ¬ 𝜑

Syntax hints:  ¬ wn 3   → wi 4

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

This theorem is referenced by:  bijust0  204  ax6dgen  2133  nlim2  8417  infn0  9202  elirrvOLD  9503  cardom  9898  0nnnALT  12182  nthruz  16178  hauspwdom  23445  fin1aufil  23876  rectbntr0  24777  lgam1  27030  gam1  27031  konigsberg  30332  ex-po  30510  strlem1  32325  eulerpartlemt  34528  nalfal  36597  bj-mt2bi  36768  finxpreclem3  37598  nregmodel  45258  tannpoly  47136