Theorem mt4 137

Description: The rule of modus tollens. Inference associated with con4i 130. (Contributed by Wolf Lammen, 12-May-2013.)

Hypotheses

Ref	Expression
mt4.1
mt4.2

Assertion

Ref	Expression
mt4

Proof of Theorem mt4

Step	Hyp	Ref	Expression
1		mt4.1	. 2
2		mt4.2	. . 3
3	2	con4i 130	. 2
4	1, 3	ax-mp 5	1

Syntax hints:  -.wn 3  ->wi 4

This theorem is referenced by:  infeq5i  8074  chirredi  27313

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