Graph Distinguishability and the Generation of Non-Isomorphic Labellings




Bird, William Herbert

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A distinguishing colouring of a graph G is a labelling of the vertices of G with colours such that no non-trivial automorphism of G preserves all colours. The distinguishing number of G is the minimum number of colours in a distinguishing colouring. This thesis presents a survey of the history of distinguishing colouring problems and proves new bounds and computational results about distinguishability. An algorithm to generate all labellings of a graph up to isomorphism is presented and compared to a previously published algorithm. The new algorithm is shown to have performance competitive with the existing algorithm, as well as being able to process automorphism groups far larger than the previous limit. A specialization of the algorithm is used to generate all minimal distinguishing colourings of a set of graphs with large automorphism groups and compute their distinguishing numbers.



Distinguishing Number, Sims Table, Schreier-Sims Algorithm, Computational Group Theory, Graph Algorithms, List-Distinguishing Colouring, Distinguishing Colouring, List-Distinguishing Number, Combinatorial Generation, Permutation Groups