منابع مشابه
On Voltage Graphs and Cages
Using voltage graphs, we construct the the smallest known trivalent graph of girth 16. The graph has 960 vertices and is a lift of the Petersen graph. By way of preparation, other lifts of the Petersen graph are discussed. AMS Subject Classifications: 05C25, 05C35
متن کاملVoltage Graphs, Group Presentations and Cages
We construct smallest known trivalent graphs for girths 16 and 18. One construction uses voltage graphs, and the other coset enumeration techniques for group presentations. AMS Subject Classifications: 05C25, 05C35
متن کاملCritical groups of covering, voltage and signed graphs
Graph coverings are known to induce surjections of their critical groups. Here we describe the kernels of these morphisms in terms of data parametrizing the covering. Regular coverings are parametrized by voltage graphs, and the above kernel can be identified with a naturally defined voltage graph critical group. For double covers, the voltage graph is a signed graph, and the theory takes a par...
متن کاملComposition of regular coverings of graphs and voltage assignments
Consider a composition of two regular coverings π1 : Γ0 → Γ1 and π2 : Γ1 → Γ2 of graphs, given by voltage assignments α1, α2 on Γ1, Γ2 in groups G1 and G2, respectively. In the case when π2 ◦ π1 is regular we present an explicit voltage assignment description of the composition in terms of G1, G2, α1, α2, and walks in Γ1.
متن کاملA Voltage Scheduling Heuristic for Real-Time Task Graphs
Energy constrained complex real-time systems are becoming increasingly important in defense, space, and consumer applications. In this paper, we present a sensible heuristic to address the problem of energy-efficient voltage scheduling of a hard real-time task graph with precedence constraints for a multi-processor environment. We show that consideration of inter-relationships among the tasks i...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 1974
ISSN: 0012-365X
DOI: 10.1016/0012-365x(74)90006-5