Journal of Lanzhou University of Technology ›› 2025, Vol. 51 ›› Issue (3): 156-160.

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Maximal (completely) isolated subsemigroups of semigroup BI(n,r)

LUO Yong-gui, XIAO Jian, YU Jiang-hui   

  1. College of Mathematical Sciences, Guizhou Normal University, Guiyang 550025, China
  • Received:2023-05-04 Online:2025-06-28 Published:2025-06-30

Abstract: Let In and Sn be symmetric inverse semigroup and symmetric group on the finite set Xn={1,2,…,n}, respectively. For 0≤r≤n-1, put I(n,r)={α∈In:|im(α)|≤r}, then the I(n,r) is a two-sided ideals of symmetric inverse semigroup In. Denote Bn=〈δn〉, where there is i δn=n+1-i for any i∈Xn, saying that Bn is a circle group on Xn. By analyzing the Green’s relation and generative relation of the semigroup BI(n,r)=I(n,r)∪Bn, the complete classification of the (completely) isolated subsemigroups of BI(n,r) is obtained. Furthermore, the coincide of maximal isolated subsemigroups and maximal completely isolated subsemigroups of BI(n,r) be proved.

Key words: symmetric inverse semigroup, symmetric group, circle group, (compeletly) isolated subsemigroups, the maximal (completely) isolated subsemigroups

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