Bipartite ${(6,3)}_6$-biregular graphs which do not allow interval coloring
Daghestan Electronic Mathematical Reports, Tome 1 (2014), pp. 71-78.

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The proposed in the article search elimination algorithm reduces the problem of finding of a non-colorable graph to building the tree of 11645 nodes, 2485 of which are last level nodes; nodal graphs of the last level form the desired set $M_0$ of ${(6,3)}_6$-graphs. The program found among them just 62 non-colorable graphs, and for $n\le 5$ it constructed colorings for all graphs from the sets – analogues of $M_0$ for considered $n$. Thus specification of minimal $n$, for which the non-colorable ${(6,3)}_6$-graph exists was obtained.
Keywords: bipartite graph, interval edge coloring, job shop scheduling.
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A. M. Magomedov. Bipartite ${(6,3)}_6$-biregular graphs which do not allow interval coloring. Daghestan Electronic Mathematical Reports, Tome 1 (2014), pp. 71-78. http://geodesic.mathdoc.fr/item/DEMR_2014_1_a2/

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