Ellis–Friedgut–Pilpel conjecture on extremal t-intersecting families of permutations
Ellis–Friedgut–Pilpel conjecture on extremal t-intersecting families of permutations
Let be the symmetric group, and let denote the set of fixed points of . A family is -intersecting if any two of its permutations agree on at least points. For with , , define
Ellis–Friedgut–Pilpel conjecture. For any and , the maximum size of a -intersecting family in is attained by one of the families . In particular, for all , the maximum is attained by the -umvirate
Furthermore, every maximum-sized -intersecting family is a double translate for some and some . The source presents this as a daring conjecture after noting earlier partial results; the supplied status is unknown.
Sources & referencesView supporting material
Primary source
Nathan Keller, Andrey Kupavskii, Noam Lifshitz and Ohad Sheinfeld, “A Complete Intersection Theorem for Large Permutation Groups”, arXiv:2607.00318 (2026).
Additional references
2 papers in this index state this conjecture (2024–2026). The statement above is taken from the most recent of them; the others are arXiv:2405.07843.
Progress summary
Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.
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