Properties of the Steiner triple systems of order 19.
Pseudodual grids and extensions of generalized quadrangles.
Quantum permutations, Hadamard matrices, and the search for matrix models
This is a presentation of recent work on quantum permutation groups, complex Hadamard matrices, and the connections between them. A long list of problems is included. We include as well some conjectural statements about matrix models.
Quasicrystallography: some interesting new patterns
Quasigroup automorphisms and symmetric group characters
The automorphisms of a quasigroup or Latin square are permutations of the set of entries of the square, and thus belong to conjugacy classes in symmetric groups. These conjugacy classes may be recognized as being annihilated by symmetric group class functions that belong to a -ideal of the special -ring of symmetric group class functions.
Quasigroups and tactical systems.
Quasigroups arisen by right nuclear extension
The aim of this paper is to prove that a quasigroup with right unit is isomorphic to an -extension of a right nuclear normal subgroup by the factor quasigroup if and only if there exists a normalized left transversal to in such that the right translations by elements of commute with all right translations by elements of the subgroup . Moreover, a loop is isomorphic to an -extension of a right nuclear normal subgroup by a loop if and only if is middle-nuclear, and there exists...
Quelles tuiles ! (Pavages apériodiques du plan et automates bidimensionnels)
La récente découverte des “quasicristaux” et leurs liens avec les pavages de Penrose ont entraîné un regain d'intérêt pour les pavages apériodiques du plan. Nous montrons ici que le pavage régulier de Robinson est engendré par un automate fini bidimensionnel, et qu'il donne une généralisation à deux dimensions du pliage de papier.
Quintuplication of Room Squares
-rozměrné konfigurace. II.
Radonpartitionen und konvexe Polyeder.
Random matrices, magic squares and matching polynomials.
Rank three geometries associated with .
Ranks of Incidence Matrices of Steiner Triple Systems.
Ranks of permutative matrices
A new type of matrix, termed permutative, is defined and motivated herein. The focus is upon identifying circumstances under which square permutative matrices are rank deficient. Two distinct ways, along with variants upon them are given. These are a special kind of grouping of rows and a type of partition in which the blocks are again permutative. Other, results are given, along with some questions and conjectures.
Rank-three matroids are Rayleigh.
Rational congruence for uniform multiplicative designs.
Rational model of the subspace complement on atomic complexes.
Real time asymptotic packing.
Recouvrements d'un rectangle de largeur 3 à l'aide de triminos
On établit une récurrence du 6-ième ordre pour le nombre de recouvrements d'un rectangle de largeur 3 et de longueur n à l'aide de «triminos». Des problèmes analogues peuvent se poser à propos de découpages électoraux.