Theorem mt2 203

Description: A rule similar to modus tollens. Inference associated with con2i 140. (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 196	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  207  ax6dgen  2163  nlim2  8476  infn0  9263  elirrvOLDOLD  9562  cardom  9973  0nnnALT  12274  nthruz  16310  hauspwdom  23639  fin1aufil  24070  rectbntr0  24971  lgam1  27209  gam1  27210  konigsberg  30589  ex-po  30767  strlem1  32583  eulerpartlemt  34742  nalfal  36895  bj-mt2bi  37141  finxpreclem3  38020  nregmodel  45709  quantgodelALT  47572  tannpoly  47610