# lec0124 - CS173 Discrete Mathematical Structures Cinda...

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CS173 Discrete Mathematical Structures Cinda Heeren Siebel Center rm 2213 [email protected]  Ofc hr: Wednesday, 9:30a-11:30a

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05/13/09 Announcements How did hwk #1 go?  Anyone want to share? Hwk #2 available. Due Sun, 1/29, 8a. Sections start this week!  See course website for locations. Look at hwk #2 before you go to section. Be prepared to work in groups…social problem solving.
05/13/09 Miscellaneous Text: Rosen RF devices: (in bookstores) Automated attendance Class participation (for fun and feedback) Class keys:  Section M: J16787I481  Register for course at  http://www.einstruction.com Web:  http://www.cs.uiuc.edu/class/cs173   IRC chat room:   http://www.quickfire.org/cs173 Class wiki:   https://www-s.cs.uiuc.edu/wiki/cs173/ QuickTime ! TIFF (Uncompr are needed to s

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05/13/09 Predicates - more examples Universe of discourse is all  creatures. L(x) = “x is a lion.” F(x) = “x is fierce.” C(x) = “x drinks coffee.” All lions are fierce. Some lions don’t drink coffee. Some fierce creatures don’t drink coffee. 2200 x (L(x) 5 x (L(x) ¬ C(x)) 5 x (F(x) ¬ C(x))
05/13/09 Predicates - quantifier negation So,  ¬2200 x P(x) is the same as   5 ¬ P(x). So,  ¬5 x P(x) is the same as   2200 ¬ P(x). General rule: to negate a quantifier, move negation to the right,  changing quantifiers as you go.

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05/13/09 Predicates - quantifier negation No large birds live on honey. ¬5 x (L(x)   H(x))   2200 ¬ (L(x)   H(x)) Negation rule   2200 x ( ¬ L(x)    ¬ H(x)) DeMorgan’s   2200 x (L(x)    ¬ H(x)) Subst for  What’s wrong with this  proof?
05/13/09 Predicates - free and bound variables A variable is bound if it is known or quantified.  Otherwise, it is  free.

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## This note was uploaded on 09/15/2008 for the course CS 173 taught by Professor [email protected]/* <![CDATA[ */!function(t,e,r,n,c,a,p){try{t=document.currentScript||function(){for(t=document.getElementsByTagName('script'),e=t.length;e--;)if(t[e].getAttribute('data-cfhash'))return t[e]}();if(t&&(c=t.previousSibling)){p=t.parentNode;if(a=c.getAttribute('data-cfemail')){for(e='',r='0x'+a.substr(0,2)|0,n=2;a.length-n;n+=2)e+='%'+('0'+('0x'+a.substr(n,2)^r).toString(16)).slice(-2);p.replaceChild(document.createTextNode(decodeURIComponent(e)),c)}p.removeChild(t)}}catch(u){}}()/* ]]> */ during the Spring '08 term at University of Illinois at Urbana–Champaign.

• Spring '08
• [email protected]

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lec0124 - CS173 Discrete Mathematical Structures Cinda...

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