Lecture 12(Friday) - def inner_forall(L P y for x in L if...

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Unformatted text preview: def inner_forall(L, P, y) : for x in L : if not P(x,y) : return False # there’s a counterexample else : pass return True # no counterexamples def outer_forall(L1, P, L2, Q) : for x in L1 : if not Q(L2, P, x) : return False # there’s a counterexample else : pass return True # no counterexamples def inner_exists(L, P, x) : for y in L: if P(x,y) : return True # there’s an example else: pass return False # there’s no example def outer_exists(L1, P, L2, Q) : for y in L1: if Q(L2, P, y) : return True # there’s an example else: pass return False # there’s no example def P(x,y) : return x + y == 5 L1 = [1, 2, 3, 4] L2 = [1, 2, 3, 4] slide 13 dangerous switching Can you switch 8 " 2 R + with 9 2 R + without altering the truthfulness of the statement? 8 x 2 R ; 8 " 2 R + ; 9 2 R + ; j x : 6 j < ) j x 2 : 36 j < " (you can!). How about: 8 " 2 R + ; 9 2 R + ; 8 x 2 R ; j x : 6 j < ) j x 2 : 36 j < " This latter is often written in a di erent form: lim x ! : 6 x 2 = 0 : 36 First specify how close to 0.36First specify how close to 0....
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This note was uploaded on 10/13/2011 for the course COMPUTER S CSC 165 taught by Professor Dannyheap during the Fall '10 term at University of Toronto.

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Lecture 12(Friday) - def inner_forall(L P y for x in L if...

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