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My question relates to the power set of any set S, denoted P(S). + is defined by +: u+v-> (uUv)\(unv) (U=union, n=intersection, \=complement), x is defined by x: uv-> unv, for u, v members of P(S). The identity law states that there exist 1 a member of P(S) such that 1 is not equal to 0 and a1=1a=a for all a members of S. But when S is the empty set, 1=0=empty set. So, is it still a commutative ring with unity?

2006-10-10 11:16:18 · 2 answers · asked by friendly_220_284 2 in Science & Mathematics Mathematics

2 answers

Strangely, it depends on who you ask. Some abstract algebra authors specifically require that 1 and 0 are distinct, thus specifically excluding trivial rings that contain only one element. Not all require this, though.

2006-10-10 11:30:42 · answer #1 · answered by James L 5 · 1 0

This is author dependent. It would not be unreasonable to just exclude the empty set, however.

2006-10-10 11:40:09 · answer #2 · answered by mathematician 7 · 0 0

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