DM
2008
13 years 4 months ago
2008
In the present note, we investigate schemes S in which each element s satisfies ns 2 and nss = 2. We show that such a scheme is schurian. More precisely, we show that it is isomor...
DM
2008
13 years 4 months ago
2008
A nonincreasing sequence of nonnegative integers = (d1, d2, ..., dn) is graphic if there is a (simple) graph G of order n having degree sequence . In this case, G is said to reali...
DM
2008
13 years 4 months ago
2008
Riordan paths are Motzkin paths without horizontal steps on the x-axis. We establish a correspondence between Riordan paths and (321, 3
DM
2008
13 years 4 months ago
2008
A family F of k-graphs is called non-principal if its Tur
DM
2008
13 years 4 months ago
2008
A simple graph G is k-ordered (respectively, k-ordered hamiltonian) if, for any sequence of k distinct vertices v1, . . . , vk of G, there exists a cycle (respectively, a hamilton...
DM
2008
13 years 4 months ago
2008
DM
2008
13 years 4 months ago
2008
Owari is an old African game that consists of cyclically ordered pits that are filled with pebbles. In a sowing move all the pebbles are taken out of one pit and distributed one b...
DM
2008
13 years 4 months ago
2008
We use K n to denote the bidirected complete graph on n vertices. A nomadic Hamiltonian decomposition of K n is a Hamiltonian decomposition, with the additional property that &quo...
DM
2008
13 years 4 months ago
2008
A covering array CA(N; t, k, v) is an N
DM
2008
13 years 4 months ago
2008
By a nearlattice is meant a join-semilattice having the property that every principal filter is a lattice with respect to the semilattice order. We introduce the concept of (relat...