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| | Sets, Groups, Rings and Algebras (Site not responding. Last check: 2007-10-22) |
 | | Operations on sets: Membership test: is x an element of S Cardinality: S is the notation for the cardinality of the set S Set union: Let A and B be sets, A union B = { x |
 | | Addition and multiplication are commonly used for convenience, yet the logical operations "and" and "or could be used, the set operations union and intersection could be used, as well as many other pairs of operations. |
 | | Addition is well defined, for every ordered pair a, b in S, c = a+b implies c is a unique element in S. Multiplication is well defined, for every ordered pair a, b in S, c = a*b implies c is a unique element in S. Associative Laws: A1. |
| www.cs.umbc.edu /help/theory/group_def.shtml (1295 words) |
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