4 papers
A collection of open problems in celebration of Imre Leader's 60th birthday
Rahil Baber, Natalie Behague, Asier Calbet +10
One of the great pleasures of working with Imre Leader is to experience his infectious delight on encountering a compelling combinatorial problem. This collection of open problems…
Correlation for permutations
J. Robert Johnson, Imre Leader, Eoin Long
In this note we investigate correlation inequalities for `up-sets' of permutations, in the spirit of the Harris--Kleitman inequality. We focus on two well-studied partial orders on…
Vertex Turán problems in the hypercube
J. Robert Johnson, John Talbot
Let be the -dimensional hypercube: the graph with vertex set and edges between vertices that differ in exactly one coordinate. For an…
Universal cycles for permutations
J. Robert Johnson
A universal cycle for permutations is a word of length n! such that each of the n! possible relative orders of n distinct integers occurs as a cyclic interval of the word. We show…