Intersecting Families in the Alternating Group and Direct Product of Symmetric Groups

  • Cheng Yeaw Ku
  • Tony W. H. Wong


Let $S_{n}$ denote the symmetric group on $[n]=\{1, \ldots, n\}$. A family $I \subseteq S_{n}$ is intersecting if any two elements of $I$ have at least one common entry. It is known that the only intersecting families of maximal size in $S_{n}$ are the cosets of point stabilizers. We show that, under mild restrictions, analogous results hold for the alternating group and the direct product of symmetric groups.

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