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Generalising from consensus to supertree methods

Thursday 6th September 2007 - 15:50 to 16:10
INI Seminar Room 1

There have been a number of attempts to generalise from consensus methods to supertree analogues that are equivalent to the consensus method in the consensus case and which preserve desirable properties of the method beyond consensus. Recently, Cotton and Wilkinson (2007) used a characterisation of the classical majority-rule consensus tree in terms of its minimisation of the sum of consensus tree to input tree distances as a basis for generalisation to the supertree case. Here I use the same general approach to generalise from strict, loose (= semi-strict) classical and reduced consensus to the corresponding supertree methods. Not all properties of the consensus methods can be simultaneously generalised beyond consensus and not all properties are desirable in the supertree case. Useful generalisation requires that we distinguish between those consensus properties that are 'essential' or 'most desirable' beyond consensus and those that seem to be merely a consequence of the special case of consensus. The loose supertree method is compared to other supertree methods, particularly to an alternative generalisation of the semi-strict consensus due to Goloboff and Pol (2002) which, it is argued, preserves consensus properties that are unhelpful more generally.

Cotton, J. A., and M. Wilkinson. 2007. Majority-rule supertrees. Systematic Biology 56: 445-452.

Goloboff, P. A., and D. Pol. 2002. Semi-strict supertrees. Cladistics 18: 514-525.

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University of Cambridge Research Councils UK
    Clay Mathematics Institute London Mathematical Society NM Rothschild and Sons