TY - JOUR
AU - MIRUMYAN, A. N.
AB -  -- As is shown in [1] any bipartite multigraph G has the following property. If for some regular edge-colouring of G with n colours, n > 3, all the subgraphs generated by the edges of any three colours are uniquely 3-colourable, then G is uniquely n-colourable. In the present paper we show that, for any n > 4 and m > 3, there exist -regular multigraphs with 2m vertices which do not possess the mentioned property. These multigraphs are counter-examples to the Kotzig problem [2] on transformations of edge-colourings of regular multigraphs. We consider finite non-oriented multigraphs without loops. (Harary's terminology [3] is used.) Let G be an -regular multigraph with 2m vertices, n > 3. A subset of m pairwise non-adjacent edges of G is called a 1-factor of G. A colouring in which each edge is coloured in one of n colours and adjacent edges are coloured in different colours is called a regular colouring of edges of G with n colours or simply -colouring. For -colouring of G, a subgraph, which is generated by all the edges of some k colours, is called a fc-colour subgraph. A multigraph G is called -colourable if it has 
TI - Counter-examples to the Kotzig problem
JF - Discrete Mathematics and Applications
DO - 10.1515/dma.1993.3.1.59
DA - 1993-01-01
UR - https://www.deepdyve.com/lp/de-gruyter/counter-examples-to-the-kotzig-problem-yXzuVGwROS
SP - 59
EP - 62
VL - 3
IS - 1
DP - DeepDyve
ER -