Intersection density conjectures for transitive permutation groups
Intersection density conjectures for transitive permutation groups
Let be a transitive permutation group. For , write and define the intersection density of by
where is intersecting if for every there exists such that .
Intersection density conjectures. (i) If is a prime power, then . (ii) If , where is an odd prime, then . (iii) If , where and are two odd primes, then .
These conjectures extend the Erdős–Ko–Rado theorem to transitive permutation groups and seek sharp restrictions on the size of intersecting families. The third assertion was disproved by constructing transitive groups of degree , with , whose intersection density is ; consequently, the combined conjectural statement is refuted.
Progress summary
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Sources & referencesView supporting material
Primary source
Roghayeh Maleki and Andriaherimanana Sarobidy Razafimahatratra, “The Erdős-Ko-Rado Theorem for non-quasiprimitive groups of degree 3p”, arXiv:2309.09906 (2023).
Additional references
2 papers in this index state this conjecture (2021–2023). The statement above is taken from the most recent of them; the others are arXiv:2109.05392.
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