A note on the combinatorial derivation of nonsmall sets

作者：Erde Joshua^*

来源：The New York Journal of Mathematics, 2014, 20: 921-925.

• Subset combinatorics of groups
• combinatorial derivation
• large and small subsets of groups

Given an infinite group G and a subset A of G we let Delta(A) ={g is an element of G: vertical bar gA boolean AND A vertical bar = infinity} (this is sometimes called the combinatorial derivation of A). A subset A of G is called: large if there exists a finite subset F of G such that FA = G; Delta-large if Delta(A) is large and small if for every large subset L of G, (G\ A) boolean AND L is large. In this note we show that every nonsmall set is Delta-large, answering a question of Protasov.

• 出版日期2014