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Irregular networks, regular graphs and integer matrices with distinct row and column sums. (English) Zbl 0685.05029
A network is a simple graph to which each edge is assigned a positive integer value or weight. The degree of a vertex in a network is the sum of weights of its incident edges. A network is irregular if all the vertices have distinct degrees. The strength of a network is the maximum weight assigned to any edge, while the irregularity strength s(G) of a graph G is the minimum strength among irregular networks with underlying graph G. It is known that if G is an r-regular graph of order n then $$s(G)\geq (n+r-1)/r.$$ In this paper infinitely many r-regular graphs with $$s(G)=(n+r-1)/r$$ are exhibited and it is proved that $$s(G)\leq [n/2]+2$$ if r is even. Also positive integer matrice with distinct row and column sums having the smallest possible maximal entry are studied.
Reviewer: V.Fleischer

##### MSC:
 05C50 Graphs and linear algebra (matrices, eigenvalues, etc.) 94C99 Circuits, networks
##### Keywords:
biparticle graph; strength of a network; regular graph
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##### References:
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