Date: Wed, 22 Aug 2007 18:06:54 -0500 (CDT) From: Mark Jacobson To: 810-080-02-fall@uni.edu Subject: Handout for Thursday class #2 (Aug 23rd) Discrete Hi 080 discrete structures students, Recall that at least 8 students do not have a textbook until next Monday. I found a very nice handout for tommorrow's class. It is online at University of Victoria (U Vic for short) and page one of it is a good summary of the syntax and semantics of the propositional logic we have covered so far this week. http://www.math.uvic.ca/faculty/gmacgill/guide/logic.pdf It is a nice summary what we covered so far (page 1 only - ignore pages 2, 3, 4 and 5 for now). Reviews negation, conjunction (and), disjunction (or), implication. We did NOT cover biconditional or exclusive or yet, but will cover those very soon. The OR that we studied is called INCLUSIVE OR. Exclusive OR would often be written as XOR for eXclusive OR. - -- - -- XOR is only true when exactly one and only one of its two propositions is true. p XOR q is true means either p is true with q false or p is false with q being true. If you can correctly answer these ten questions on the game show, you win either a new corvette or an all expenses paid four week trip for two to europe. This would be an XOR, probably. The game show would correct you if you interpreted it as an INCLUSIVE OR, and said, "Oh wow, I won! I think we will take the 4 week vacation to Europe and then come back to travel around in our new Corvette showing them all the photos and telling them about the exciting free trip." The game show would say: You are the owner of You get to go on the vacation a brand new Corvette XOR of a lifetime --- Read page 1 of the following URL, if you get a chance. I will hand it out in class tommorrow. http://www.math.uvic.ca/faculty/gmacgill/guide/logic.pdf http://www.cns.uni.edu/~jacobson/c080.html Mark