Document Detail


Untangling tanglegrams: comparing trees by their drawings.
MedLine Citation:
PMID:  20530818     Owner:  NLM     Status:  In-Process    
Abstract/OtherAbstract:
A tanglegram is a pair of trees on the same set of leaves with matching leaves in the two trees joined by an edge. Tanglegrams are widely used in biology--to compare evolutionary histories of host and parasite species and to analyze genes of species in the same geographical area. We consider optimization problems in tanglegram drawings. We show a linear time algorithm to decide if a tanglegram admits a planar embedding by a reduction to the planar graph drawing problem. This problem was also studied by Fernau et al. A similar reduction to a graph crossing problem also helps to solve an open problem they posed, showing a fixed-parameter tractable algorithm for minimizing the number of crossings over all d-ary trees. For the case where one tree is fixed, we show an O(n log n) algorithm to determine the drawing of the second tree that minimizes the number of crossings. This improves the bound from earlier methods. We introduce a new optimization criterion using Spearman's footrule distance and give an O(n²) algorithm. We also show integer programming formulations to quickly obtain tanglegram drawings that minimize the two optimization measures discussed. We prove lower bounds on the maximum gap between the optimal solution and the heuristic of Dwyer and Schreiber to minimize crossings.
Authors:
Balaji Venkatachalam; Jim Apple; Katherine St John; Dan Gusfield
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  IEEE/ACM transactions on computational biology and bioinformatics / IEEE, ACM     Volume:  7     ISSN:  1557-9964     ISO Abbreviation:  IEEE/ACM Trans Comput Biol Bioinform     Publication Date:    2010 Oct-Dec
Date Detail:
Created Date:  2010-11-05     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101196755     Medline TA:  IEEE/ACM Trans Comput Biol Bioinform     Country:  United States    
Other Details:
Languages:  eng     Pagination:  588-97     Citation Subset:  IM    
Affiliation:
Department of Computer Science, UC Davis, One Shields Avenue, Davis, CA 95616, USA. balaji@cs.ucdavis.edu
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