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Four-colorings of maximal outerplanar graphs under boundary conditions. (Chinese. English summary) Zbl 0959.05053
Summary: Four colourings of maximum outerplanar graphs are studied by their diagonal transformations and the concept of a characteristic vector is given. It is proved that for any two maximum outerplanar graphs with a common boundary circuit, one can be obtained from the other by a series of diagonal transformations. Furthermore, it is proved that under some conditions two maximum outerplanar graphs with a common boundary circuit have common four colourings.
MSC:
05C15 Coloring of graphs and hypergraphs
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