COMBINATORICS
2002
13 years 11 months ago
2002
COMBINATORICS
2002
13 years 11 months ago
2002
COMBINATORICS
2002
13 years 11 months ago
2002
COMBINATORICS
2002
13 years 11 months ago
2002
Erdos, Rubin, and Taylor found a nice correspondence between the minimum order of a complete bipartite graph that is not r-choosable and the minimum number of edges in an r-unifor...
COMBINATORICS
2002
13 years 11 months ago
2002
Fix a rectangular Young diagram R, and consider all the products of Schur functions ssc , where and c run over all (unordered) pairs of partitions which are complementary with re...
COMBINATORICS
2002
13 years 11 months ago
2002
Let s(N) denote the edge length of the smallest square in which one can pack N unit squares. A duality method is introduced to prove that s(6) = s(7) = 3. Let nr be the smallest i...
COMBINATORICS
2002
13 years 11 months ago
2002
COMBINATORICS
2002
13 years 11 months ago
2002
We consider permutations that avoid the pattern 1324. By studying the generating tree for such permutations, we obtain a recurrence formula for their number. A computer program pr...
COMBINATORICS
2002
13 years 11 months ago
2002
A 321-k-gon-avoiding permutation avoids 321 and the following four patterns: k(k + 2)(k + 3)
COMBINATORICS
2002
13 years 11 months ago
2002
Let In() denote the number of involutions in the symmetric group Sn which avoid the permutation . We say that two permutations , Sj may be exchanged if for every n, k, and order...