Displaying similar documents to “Colouring Platonic Solids”

On improper interval edge colourings

Peter Hudák, František Kardoš, Tomáš Madaras, Michaela Vrbjarová (2016)

Czechoslovak Mathematical Journal

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We study improper interval edge colourings, defined by the requirement that the edge colours around each vertex form an integer interval. For the corresponding chromatic invariant (being the maximum number of colours in such a colouring), we present upper and lower bounds and discuss their qualities; also, we determine its values and estimates for graphs of various families, like wheels, prisms or complete graphs. The study of this parameter was inspired by the interval colouring, introduced...

Constrained Colouring and σ-Hypergraphs

Yair Caro, Josef Lauri, Christina Zarb (2015)

Discussiones Mathematicae Graph Theory

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A constrained colouring or, more specifically, an (α, β)-colouring of a hypergraph H, is an assignment of colours to its vertices such that no edge of H contains less than α or more than β vertices with different colours. This notion, introduced by Bujtás and Tuza, generalises both classical hypergraph colourings and more general Voloshin colourings of hypergraphs. In fact, for r-uniform hypergraphs, classical colourings correspond to (2, r)-colourings while an important instance of...