منابع مشابه
Recognizing Median Graphs in Subquadratic Time
Motivated by a dynamic location problem for graphs, Chung, Graham and Saks introduced a graph parameter called windex. Graphs of windex 2 turned out to be, in graph-theoretic language, retracts of hypercubes. These graphs are also known as median graphs and can be characterized as partial binary Hamming graphs satisfying a convexity condition. In this paper an O(n 3 2 logn) algorithm is present...
متن کاملPseudo-median graphs are join spaces
Bandelt, H.-J. and H.M. Mulder, Pseudo-median graphs are join spaces, Discrete Mathematics 109 (1992) 13-26. Median graphs are known to share a number of geometrica! properties with Euclidean space, as is testified by the fact that median graphs ale (c!osed) join spaces-the segments of the associated join space being the geodesic intervals of the graph. As is shown in this paper the median join...
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 کاملOn median graphs and median grid graphs
Let G be a Q4-free median graph on n vertices and m edges. Let k be the number of equivalence classes of Djoković-Winkler’s relation Θ and let h be the number of Q3’s in G. Then we prove that 2n −m − k + h = 2. We also characterize median grid graphs in several different ways, for instance, they are the grid graphs with m− n + 1 squares. To obtain these results we introduce the notion of square...
متن کاملRelations between Median Graphs, Semi-median Graphs and Partial Cubes
A rich structure theory has been developed in the last three decades for graphs embed dable into hypercubes in particular for isometric subgraphs of hypercubes also known as partial cubes and for median graphs Median graphs which constitute a proper subclass of partial cubes have attracted considerable attention In order to better understand them semi median graphs have been introduced but have...
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ژورنال
عنوان ژورنال: Discrete Applied Mathematics
سال: 2002
ISSN: 0166-218X
DOI: 10.1016/s0166-218x(00)00327-9