Generators and relations for subsemigroups via boundaries in Cayley graphs

被引:2
作者
Gray, R. [1 ]
Ruskuc, N. [2 ]
机构
[1] Univ Lisbon, Ctr Algebra, P-1649003 Lisbon, Portugal
[2] Univ St Andrews, Sch Math & Stat, St Andrews KY16 9SS, Fife, Scotland
基金
英国工程与自然科学研究理事会;
关键词
METABELIAN-GROUPS; SPECIAL MONOIDS; SEMIGROUPS; SUBGROUPS; PRESENTATIONS; INDEX;
D O I
10.1016/j.jpaa.2011.03.017
中图分类号
O29 [应用数学];
学科分类号
070104 ;
摘要
Given a finitely generated semigroup S and subsemigroup T of S. we define the notion of the boundary of T in S which, intuitively, describes the position of T inside the left and right Cayley graphs of S. We prove that if S is finitely generated and T has a finite boundary in S then T is finitely generated. We also prove that if S is finitely presented and T has a finite boundary in S then T is finitely presented. Several corollaries and examples are given. (C) 2011 Elsevier B.V. All rights reserved.
引用
收藏
页码:2761 / 2779
页数:19
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