Evènement pour le groupe GT Graphes et Applications

Date 2011-05-20  14:00-15:00
TitreNowhere-zero flows in Cartesian bundles of graphs 
RésuméA nowhere-zero k-flow on a graph G is an assignment of a direction and a non-zero integer in absolute value smaller than k to each edge of G in such a way that, for each vertex, the sum of incoming values equals the sum of outgoing values. Our work continues and extends the study of nowhere-zero flows on product graphs initiated by Imrich and Skrekovski in 2003. hey proved that the Cartesian product of any two nontrivial connected graphs has a nowhere-zero 4-flow. Product graphs have been examined for many different graph properties because of their relatively simple structure and considerable generality. We have examined a natural (although lesser known) generalisation of the Cartesian product called Cartesian bundle. By combining of flow methods with algebraic methods we will show that every Cartesian bundle of two graphs without isolated vertices has a nowhere-zero 4-flow. This is a joint work with Martin Skoviera. 
LieuSalle 178 
OrateurEdita Rollova 

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