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139
Voted
COMBINATORICS
2006
15 years 3 months ago
2006
Beauquier and Nivat introduced and gave a characterization of the class of pseudo-square polyominoes that tile the plane by translation: a polyomino tiles the plane by translation...
114
Voted
COMBINATORICS
2006
15 years 3 months ago
2006
We prove the nonexistence of several four-dimensional codes over GF(8) that meet the Griesmer bound. The proofs use geometric methods based on the analysis of the weight structure...
135
Voted
COMBINATORICS
2006
15 years 3 months ago
2006
Let h, e, and m denote the homogeneous symmetric function, the elementary symmetric function and the monomial symmetric function associated with the partition respectively. We gi...
117
Voted
COMBINATORICS
2006
15 years 3 months ago
2006
This note contains two results on the distribution of k-crossings and k-nestings in graphs. On the positive side, we exhibit a class of graphs for which there are as many k-noncro...
157
Voted
COMBINATORICS
2006
15 years 3 months ago
2006
We present an algorithm for finding a system of recurrence relations for the number of permutations of length n that satisfy a certain set of conditions. A rewriting of these rela...