DM
2008
13 years 11 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 11 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 11 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 11 months ago
2008
A family F of k-graphs is called non-principal if its Tur
DM
2008
13 years 11 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 11 months ago
2008
DM
2008
13 years 11 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 11 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 11 months ago
2008
A covering array CA(N; t, k, v) is an N
DM
2008
13 years 11 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...