Cereceda, L, van den Heuvel, Jan and Johnson, M (2007) Finding paths between 3-colourings. LSE-CDAM-2007-31. London school of economics and political science, London, UK.Full text not available from this repository.
Given a 3-colourable graph G and two proper vertex 3-colourings α and β of G, consider the following question: is it possible to transform α into β by recolouring vertices of G one at a time, making sure that all intermediate colourings are proper 3-colourings? We prove that this question is answerable in polynomial time. We do so by characterising the instances G,α,β where the transformation is possible; the proof of this characterisation is via an algorithm that either finds a sequence of recolourings between α and β, or exhibits a structure which proves that no such sequence exists. In the case that a sequence of recolourings does exist, the algorithm uses O(|V(G)|2) recolouring steps and in many cases returns a shortest sequence of recolourings. We also exhibit a class of instances G,α,β that require Ω(|V(G)|2) recolouring steps.
|Item Type:||Monograph (Report)|
|Additional Information:||© 2007 London school of economics and political science|
|Library of Congress subject classification:||H Social Sciences > H Social Sciences (General)|
|Sets:||Departments > Mathematics|
|Date Deposited:||10 Jul 2008 09:23|
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