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# Set Theory (hmk)

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I hate to use forums as a homework helper but here goes... Im trying to prove the following - If "U" is a univeral set, and "A", "B" are subsets of U, then prove... ["A" being a ''proper'' subset of B] = [NOT "B" being a ''proper'' subset of NOT "A"] If anyone knows any good axioms to begin with there I would be very greatfull (can''t wait till summer vacation....)

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Just draw a venn diagram and show it in both cases. If a is inside b and smaller then not b will be smaller then not a and included in not a.

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there should be a comma after smaller, and smaller refers to smaller then b.

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sorry, i forgot to say - he said no venn diagrams...

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Use a venn diagram to help you understand exactly what the problem is and where to start, and then you can write a proof.

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While on the subject of homework problems that are not game related, one should point out the following:

Im = I''m
greatfull = grateful

others, but you get the point

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To just give you a little help (without just answering):

1) A proper subset, A, of the set, X, is a subset such that the cardinality of A is less than the cardinality of X.

2) The negation of a set A is simply all of the elements in the universal set and not in the set A.

This should be enough information to prove the two questions.

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quote:
Original post by trub
I hate to use forums as a homework helper but here goes...

Wish I had caught that sooner. I know you''re only asking for help getting started rather than a final answer, but you don''t show any of your own work. So, I''m closing the thread. You can read the forum FAQ here to understand my policy on blatant homework questions:

http://www.gamedev.net/community/forums/showfaq.asp?forum_id=20

Graham Rhodes
Senior Scientist
Applied Research Associates, Inc.

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