Median graphs and Helly hypergraphs
نویسندگان
چکیده
منابع مشابه
Complexity Aspects of the Helly Property: Graphs and Hypergraphs∗
In 1923, Eduard Helly published his celebrated theorem, which originated the well known Helly property. A family of subsets has the Helly property when every subfamily thereof, formed by pairwise intersecting subsets, contains a common element. Many generalizations of this property exist which are relevant to some fields of mathematics, and have several applications in computer science. In this...
متن کاملFrom copair hypergraphs to median graphs with latent vertices
The purpose of this paper is to extend the Buneman construction of partially labelled trees to the general case. This extension is related with the characterization of median graphs by Mulder and Schrijver. In the first section, we construct a graph G(H) associated with a copair hypergraph H on a finite set X and define the notion of a median graph with latent vertices (called X-median graph). ...
متن کاملOn Helly Hypergraphs with Variable Intersection Sizes
A hypergraphH is said to be p-Helly when every p-wise intersecting partial hypergraph H′ of H has nonempty total intersection. Such hypergraphs have been characterized by Berge and Duchet in 1975, and since then they have appeared in the literature in several contexts, especially for the case p = 2, in which they are referred simply as Helly hypergraphs. An interesting generalization of p-Helly...
متن کاملFaster recognition of clique-Helly and hereditary clique-Helly graphs
A family of subsets of a set is Helly when every subfamily of it, which is formed by pairwise intersecting subsets contains a common element. A graph G is cliqueHelly when the family of its (maximal) cliques is Helly, while G is hereditary clique-Helly when every induced subgraph of it is clique-Helly. The best algorithms currently known to recognize clique-Helly and hereditary clique-Helly gra...
متن کاملOn Median Graphs and Median Grid Graphs on Median Graphs and Median Grid Graphs
Let e be an edge of a median graph G which is contained in exactly one 4-cycle. Then it is proved that G n e is a median graph. The converse holds as well provided that e is not contained is a subgraph isomorphic to the 3-cube minus a vertex. These results are used to give several characterizations of median grid graphs. (Grid graphs are subgraphs of complete grids, i.e. of the Cartesian produc...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1979
ISSN: 0012-365X
DOI: 10.1016/0012-365x(79)90151-1