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DM
1999
90views more  DM 1999»
13 years 11 months ago
Induced subgraphs of given sizes
We say (n, e) (m, f), an (m, f) subgraph is forced, if every n-vertex graph of size e has an m-vertex spanned subgraph with f edges. For example, as Tur
Paul Erdös, Zoltán Füredi, Bruce ...
DM
1999
75views more  DM 1999»
13 years 11 months ago
Real and integer domination in graphs
For an arbitrary subset P of the reals, we define a function f: V P to be a Pdominating function of graph G = (V, E) if the sum of the function values over any
Wayne Goddard, Michael A. Henning
DM
1999
83views more  DM 1999»
13 years 11 months ago
A characterization of uniquely vertex colorable graphs using minimal defining sets
A defining set (of vertex coloring) of a graph G is a set of vertices S with an assignment of colors to its elements which has a unique completion to a proper coloring of G. We de...
Hossein Hajiabolhassan, Mojtaba L. Mehrabadi, Ruzb...
DM
1999
73views more  DM 1999»
13 years 11 months ago
Enumeration of mosaics
Mosaics are orbits of partitions arising from music theoretical investigations. Various theorems from the field of "enumeration under finite group actions" are applied f...
Harald Fripertinger
DM
1999
79views more  DM 1999»
13 years 11 months ago
A bijective proof of Riordan's theorem on powers of Fibonacci numbers
Let Fk(x) = n=0 Fk n xn . Using the interpretation of Fibonacci numbers in the terms of Morse codes, we give a bijective proof of Riordan's formula (1 - Lkx + (-1)k x2 )Fk(x...
Andrej Dujella
DM
1999
101views more  DM 1999»
13 years 11 months ago
Characterizations of bipartite Steinhaus graphs
We characterize bipartite Steinhaus graphs in three ways by partitioning them into four classes and we describe the color sets for each of these classes. An interesting recursion ...
Gerard J. Chang, Bhaskar DasGupta, Wayne M. Dym&ag...
DM
1999
89views more  DM 1999»
13 years 11 months ago
On the distribution of eigenvalues of graphs
Let G be a simple graph with n( 2) vertices, and i(G) be the ith largest eigenvalue of G. In this paper we obtain the following: If 3(G) < 0, and there exists some index k, 2 ...
Alexander K. Kelmans, Xuerong Yong
DM
1999
69views more  DM 1999»
13 years 11 months ago
On representations of a number as a sum of three squares
Michael D. Hirschhorn, James A. Sellers
DM
1999
122views more  DM 1999»
13 years 11 months ago
Parking functions, valet functions and priority queues
We construct a bijection between labeled trees and allowable pairs of permutations sorted by a priority queue. These are also the pairs of permutations that avoid the pattern pairs...
Julian D. Gilbey, Louis H. Kalikow
DM
1999
41views more  DM 1999»
13 years 11 months ago
Superconnectivity of bipartite digraphs and graphs
Camino Balbuena, Angeles Carmona, Josep Fàb...