منابع مشابه
On Reversal and Transposition Medians
During the last years, the genomes of more and more species have been sequenced, providing data for phylogenetic reconstruction based on genome rearrangement measures. A main task in all phylogenetic reconstruction algorithms is to solve the median of three problem. Although this problem is NP-hard even for the simplest distance measures, there are exact algorithms for the breakpoint median and...
متن کاملReversal and Transposition Distance of Linear Chromosomes
In recent years we are seeing increasing interest in research on mutational events acting on large portions of the chromosomes. Among these events, a reversal acts on a fragment of a chromosome reversing the order and orientation of the genes, and a transposition moves fragments from one region to another within a chromosome. In this article we analyze genomes evolving by reversals and transpos...
متن کاملA Lower Bound on the Reversal and Transposition Diameter
One possible model to study genome evolution is to represent genomes as permutations of genes and compute distances based on the minimum number of certain operations (rearrangements) needed to transform one permutation into another. Under this model, the shorter the distance, the closer the genomes are. Two operations that have been extensively studied are the reversal and the transposition. A ...
متن کاملQuantiles and Medians
We provide a list of functional equations that characterize quantile functions for collections of bounded and measurable functions. Our central axiom is ordinal covariance. When a probability measure is exogeneously given, we characterize quantiles with respect to that measure through monotonicity with respect to stochastic dominance. When none is given, we characterize those functions which ar...
متن کاملGeometric medians
We discuss several generalizations of the notion of median to points in $R^d$. They arise in Computational Geometry and in Statistics. The notions are compared with respect to some of their mathematical properties. We also consider computational aspects. The issue of computational complexity raises several intriguing questions.
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2007
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2006.12.006