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Motivated by the problem in computational biology of reconstructing the series of chromosome inversions by which one organism evolved from another, we consider the problem of computing the shortest series of reversals that transform one permutation to another. The permutations describe the order of genes on corresponding chromosomes, and a reversal takes an(More)
Multiple alignment of macromolecular sequences generalizes from N = 2 to N > or = 3 the comparison of N sequences which have diverged through the local processes of insertion, deletion and substitution. Gene-order sequences diverge through non-local genome rearrangement processes such as inversion (or reversal) and transposition. In this paper we show which(More)
BACKGROUND Genome median and genome halving are combinatorial optimization problems that aim at reconstructing ancestral genomes as well as the evolutionary events leading from the ancestor to extant species. Exploring complexity issues is a first step towards devising efficient algorithms. The complexity of the median problem for unichromosomal genomes(More)
We study the problem of comparing two circular chromosomes that have evolved by chromosome inversion, assuming that the order of corresponding genes is known, as well as their orientation. Determining the minimum number of inversions is equivalent to finding the minimum of reversals to sort a signed circular permutation, where a reversal takes an arbitrary(More)
The inference of genome rearrangement requires detailed gene maps of related species. For most multichromosomal species, however , knowledge of chromosomal assignment of genes outstrips mapping data. Comparison of these species is thus a question of comparing sets of syntenic genes, without any gene order or gene orientation information. Given synteny data(More)
MOTIVATION The total order of the genes or markers on a chromosome inherent in its representation as a signed per-mutation must often be weakened to a partial order in the case of real data. This is due to lack of resolution (where several genes are mapped to the same chromosomal position) to missing data from some of the datasets used to compile a gene(More)