History of Subring

	Revision 2 . . December 16, 2001 6:08 am by AxelBoldt
	Revision 1 . . July 29, 2001 10:59 pm by Buzco

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Changed: 1c1,4

#redirect SubRing

Given a ring (R, +, *), we say that a subset S of R is a subring thereof if it is a ring under the restriction of + and * thereto, and contains the same unity as R. A subring is just a subgroup of (R, +) which contains 1 and is closed under multiplication. Every ring has a unique smallest subring, isomorphic to either the integers Z or some modular arithmetic Zn.