Some combinatorially defined subsets of beta N and their relation to the idempotents
نویسندگان
چکیده
Members of idempotents in (βN,+), especially those in the smallest ideal, have strong combinatorial properties. And the closure Γ of the set of idempotents has a simple combinatorial description. We investigate here the relationships among several subsets of βN that have simple combinatorial descriptions, as well as the semigroups they generate and their closures.
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ورودعنوان ژورنال:
- J. Comb. Theory, Ser. A
دوره 118 شماره
صفحات -
تاریخ انتشار 2011