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EJC
2008
13 years 11 months ago
Locally constrained graph homomorphisms and equitable partitions
We explore the connection between locally constrained graph homomorphisms and degree matrices arising from an equitable partition of a graph. We provide several equivalent charact...
Jirí Fiala, Daniël Paulusma, Jan Arne ...
EJC
2008
13 years 11 months ago
Catalan and Motzkin numbers modulo 4 and 8
In this paper, we compute the congruences of Catalan and Motzkin numbers modulo 4 and 8. in particular, we prove the conjecture proposed by Deutsch and Sagan that no Motzkin numbe...
Sen-Peng Eu, Shu-Chung Liu, Yeong-Nan Yeh
EJC
2008
13 years 11 months ago
Substitution tilings with statistical circular symmetry
Two new series of substitution tilings are introduced in which the tiles appear in infinitely many orientations. It is shown that several properties of the well-known pinwheel tili...
Dirk Frettlöh
EJC
2008
13 years 11 months ago
On the adaptable chromatic number of graphs
The adaptable chromatic number of a graph G is the smallest integer k such that for any edge k-colouring of G there exists a vertex kcolouring of G in which the same colour never ...
Pavol Hell, Xuding Zhu
EJC
2008
13 years 11 months ago
Some existence and construction results of polygonal designs
This paper revisits the existence and construction problems for polygonal designs (a special class of partially balanced incomplete block designs associated with regular polygons)...
Gargi Bhattacharyya, John Hegeman, Joohyung Kim, J...
EJC
2008
13 years 11 months ago
Eriksson's numbers game and finite Coxeter groups
The numbers game is a one-player game played on a finite simple graph with certain "amplitudes" assigned to its edges and with an initial assignment of real numbers to i...
Robert G. Donnelly
EJC
2008
13 years 11 months ago
Grad and classes with bounded expansion III. Restricted graph homomorphism dualities
We study restricted homomorphism dualities in the context of classes with bounded expansion. This presents a generalization of restricted dualities obtained earlier for bounded deg...
Jaroslav Nesetril, Patrice Ossona de Mendez
EJC
2008
13 years 11 months ago
On tension-continuous mappings
Tension-continuous (shortly TT) mappings are mappings between the edge sets of graphs. They generalize graph homomorphisms. From another perspective, tension-continuous mappings a...
Jaroslav Nesetril, Robert Sámal