Collineations of the Subiaco generalized quadrangles.
Colouring 4-cycle systems with specified block colour patterns: The case of embedding -designs.
Combinatorial approaches and conjectures for 2-divisibility problems concerning domino tilings of polyominoes.
Combinatorial Geometries Representable over GF(3) and GF(q). I. The Number of Points.
Combinatorial lemmas for polyhedrons
We formulate general boundary conditions for a labelling to assure the existence of a balanced n-simplex in a triangulated polyhedron. Furthermore we prove a Knaster-Kuratowski-Mazurkiewicz type theorem for polyhedrons and generalize some theorems of Ichiishi and Idzik. We also formulate a necessary condition for a continuous function defined on a polyhedron to be an onto function.
Combinatorial lemmas for polyhedrons I
We formulate general boundary conditions for a labelling of vertices of a triangulation of a polyhedron by vectors to assure the existence of a balanced simplex. The condition is not for each vertex separately, but for a set of vertices of each boundary simplex. This allows us to formulate a theorem, which is more general than the Sperner lemma and theorems of Shapley; Idzik and Junosza-Szaniawski; van der Laan, Talman and Yang. A generalization of the Poincaré-Miranda theorem is also derived.
Combinatorial Models for the Finite-Dimensional Grassmannians.
Combinatorial Obstructions to the Lifting of Weaving Diagrams.
Combinatorial Structures in Loops.
Common Transversals Of Finite Families
Common transversals of finite families.
Commutative subloop-free loops
We describe, in a constructive way, a family of commutative loops of odd order, , which have no nontrivial subloops and whose multiplication group is isomorphic to the alternating group .
Compatible factorizations and three-fold triple systems.
Complete arcs arising from a generalization of the Hermitian curve
We investigate complete arcs of degree greater than two, in projective planes over finite fields, arising from the set of rational points of a generalization of the Hermitian curve. The degree of the arcs is closely related to the number of rational points of a class of Artin-Schreier curves, which is calculated by using exponential sums via Coulter's approach. We also single out some examples of maximal curves.
Completing partial Latin squares with two filled rows and two filled columns.
Complex Hadamard Matrices contained in a Bose–Mesner algebra
Acomplex Hadamard matrix is a square matrix H with complex entries of absolute value 1 satisfying HH* = nI, where * stands for the Hermitian transpose and I is the identity matrix of order n. In this paper, we first determine the image of a certain rational map from the d-dimensional complex projective space to Cd(d+1)/2. Applying this result with d = 3, we give constructions of complex Hadamard matrices, and more generally, type-II matrices, in the Bose–Mesner algebra of a certain 3-class symmetric...
Complexity of sequences defined by billiard in the cube
Composing T-designs
Compression theorems for periodic tilings and consequences.
Computation of rigidity of order for one simple matrix
We shall compute the exact value of rigidity of the triangular matrix with entries 0 and 1.