263 search results - page 23 / 53 » ejc 2007 |
EJC
2010
14 years 9 months ago
2010
The concept of permutograph is introduced and properties of integral functions on permutographs are established. The central result characterizes the class of integral functions t...
EJC
2010
14 years 9 months ago
2010
We invesitage the multiplicative loops of finite semifields. We show that the group generated by the left and right multiplication maps contains the special linear group. This resu...
EJC
2010
14 years 9 months ago
2010
We use group theory to construct infinite families of maps on surfaces which are invariant under Wilson's map operations of order 3 but not under the operations of order 2, s...
EJC
2010
14 years 9 months ago
2010
We study two enumeration problems for up-down alternating trees, i.e., rooted labelled trees T, where the labels v1, v2, v3, . . . on every path starting at the root of T satisfy v...
EJC
2010
14 years 9 months ago
2010
We prove that for any fixed r 2, the tree-width of graphs not containing Kr as a topological minor (resp. as a subgraph) is bounded by a linear (resp. polynomial) function of the...