Motzkin paths and reduced decompositions for permutations with forbidden patterns.
Multiple pattern avoidance with respect to fixed points and excedances.
Multi-static enumeration of two-stack sortable permutations.
Nonadaptive search problem with sets of equal sum
Consider the set A={1,2,3,…,2n}, n≥3 and let x∈ A be unknown element. For given natural number S we are allowed to ask whether x belongs to a subset B of A such that the sum of the elements of B equals S. We investigate for which S it is possible to find x using a nonadaptive search.
Note on canonizing ordering theorems for Hales Jewett structures
Note on Gray Codes for Permutation Lists
Note on homomorphism interpolation theorem
Note on packing and covering Turán numbers
Note relative aux intersections intérieures des diagonales d'un polygone convexe
Note sur les permutations de objets et sur leur classement
O rekurentním vzorci k sestrojování rovin involučních
Odd graphs
On a certain numbering of the vertices of a hypergraph
On a conjecture of Frankl and Füredi.
On a conjecture of Turán
On a generalization of binomial coefficients. (Sur une généralisation des coefficients binomiaux.)
On a problem of Davenport and Schinzel
On a problem of Steinhaus concerning binary sequences.
On a Two-Dimensional Search Problem
In this article we explore the so-called two-dimensional tree− search problem. We prove that for integers m of the form m = (2^(st) − 1)/(2^s − 1) the rectangles A(m, n) are all tight, no matter what n is. On the other hand, we prove that there exist infinitely many integers m for which there is an infinite number of n’s such that A(m, n) is loose. Furthermore, we determine the smallest loose rectangle as well as the smallest loose square (A(181, 181)). It is still undecided whether there exist...
On an extension of Euler numbers and records of alternating permutations. (Sur une extension des nombres d'Euler et les records des permutations alternantes.)