On mapping graphs and permutation graphs
On Marczewski-Steinhaus type distance between hypergraphs
On maximal finite antichains in the homomorphism order of directed graphs
We show that the pairs where T is a tree and its dual are the only maximal antichains of size 2 in the category of directed graphs endowed with its natural homomorphism ordering.
On maximal matchings in and a conjecture of R. Forcade
On Maximum Weight of a Bipartite Graph of Given Order and Size
The weight of an edge xy of a graph is defined to be the sum of degrees of the vertices x and y. The weight of a graph G is the minimum of weights of edges of G. More than twenty years ago Erd˝os was interested in finding the maximum weight of a graph with n vertices and m edges. This paper presents a complete solution of a modification of the above problem in which a graph is required to be bipartite. It is shown that there is a function w*(n,m) such that the optimum weight is either w*(n,m) or...
On M.D.S. codes, arcs in PG(n,q) with q even, and a solution of three fundamental problems of B. Segre.
On metro-line crossing minimization.
On minimal energies of trees with given diameter.
On Minimal Geodetic Domination in Graphs
Let G be a connected graph. For two vertices u and v in G, a u-v geodesic is any shortest path joining u and v. The closed geodetic interval IG[u, v] consists of all vertices of G lying on any u-v geodesic. For S ⊆ V (G), S is a geodetic set in G if ∪u,v∈S IG[u, v] = V (G). Vertices u and v of G are neighbors if u and v are adjacent. The closed neighborhood NG[v] of vertex v consists of v and all neighbors of v. For S ⊆ V (G), S is a dominating set in G if ∪u∈S NG[u] = V (G). A geodetic dominating...
On minimal graphs of diameter with every edge in a -cycle
On minimal rank over finite fields.
On minimal regular digraphs with girth 4
On minimal semirigid relations
On minimal words with given subword complexity.
On Minimum (Kq, K) Stable Graphs
A graph G is a (Kq, k) stable graph (q ≥ 3) if it contains a Kq after deleting any subset of k vertices (k ≥ 0). Andrzej ˙ Zak in the paper On (Kq; k)-stable graphs, ( doi:/10.1002/jgt.21705) has proved a conjecture of Dudek, Szyma´nski and Zwonek stating that for sufficiently large k the number of edges of a minimum (Kq, k) stable graph is (2q − 3)(k + 1) and that such a graph is isomorphic to sK2q−2 + tK2q−3 where s and t are integers such that s(q − 1) + t(q − 2) − 1 = k. We have proved (Fouquet...
On minimum locally -(arc)-strong digraphs
On mixed codes with covering radius 1 and minimum distance 2.
On monochromatic paths and bicolored subdigraphs in arc-colored tournaments
Consider an arc-colored digraph. A set of vertices N is a kernel by monochromatic paths if all pairs of distinct vertices of N have no monochromatic directed path between them and if for every vertex v not in N there exists n ∈ N such that there is a monochromatic directed path from v to n. In this paper we prove different sufficient conditions which imply that an arc-colored tournament has a kernel by monochromatic paths. Our conditions concerns to some subdigraphs of T and its quasimonochromatic...
On monochromatic sets of integers whose diameters form a monotone sequence.
On monochromatic solutions of equations in groups.