Definition: Substructure
A substructure $(S,\ast)$ is a proper subset of a given algebraic structure $(X,\ast)$ which is closed under the binary operation $"\ast".$
Table of Contents
 Proposition: Subset of Powers is a Submonoid
Mentioned in:
Definitions: 1 2
Proofs: 3
Propositions: 4
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References
Bibliography
 Lang, Serge: "Algebra  Graduate Texts in Mathematics", Springer, 2002, 3rd Edition
Adapted from CC BYSA 3.0 Sources:
 Brenner, Prof. Dr. rer. nat., Holger: Various courses at the University of OsnabrÃ¼ck