Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » Math Topics » discretemath

Topic: Tautology Proof Question
Replies: 1   Last Post: Mar 19, 2012 5:51 AM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Ashraf Samhouri

Posts: 1
From: Jordan
Registered: 3/19/12
Tautology Proof Question
Posted: Mar 19, 2012 4:51 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

Hello guys,

While studying, I've passed through this proof (in the class notes):

Example:
Proof that:
( (p v q) ^ (p -> r) ^ (q -> r) ) -> r
is a tautology?

The solution is:
( (p v q) ^ (¬p v r) ^ (¬q v r) ) -> r
( (p ^ ¬p) v (r ^ q) ^ (¬q v r) ) -> r
(F v (q ^ ¬q) v r) -> r
r -> r
¬r v r
.: T

Actually I can't understand the steps, am not sure if the notes are
well-written here, but I'll appreciate any help in explaining the
proof.

Regards,
ASH



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.