1,249 research outputs found
A Duality Based 2-Approximation Algorithm for Maximum Agreement Forest
We give a 2-approximation algorithm for the Maximum Agreement Forest problem
on two rooted binary trees. This NP-hard problem has been studied extensively
in the past two decades, since it can be used to compute the Subtree
Prune-and-Regraft (SPR) distance between two phylogenetic trees. Our result
improves on the very recent 2.5-approximation algorithm due to Shi, Feng, You
and Wang (2015). Our algorithm is the first approximation algorithm for this
problem that uses LP duality in its analysis
Layers and Matroids for the Traveling Salesman's Paths
Gottschalk and Vygen proved that every solution of the subtour elimination
linear program for traveling salesman paths is a convex combination of more and
more restrictive "generalized Gao-trees". We give a short proof of this fact,
as a layered convex combination of bases of a sequence of increasingly
restrictive matroids. A strongly polynomial, combinatorial algorithm follows
for finding this convex combination, which is a new tool offering polyhedral
insight, already instrumental in recent results for the path TSP
Perioperative brain functioning:Effects of anesthesia on neurometabolism, cognition and sleep-wake timing
Pour une esthétique du comique : L’Enfant de Jules Vallès
L'article analyse le mode d'emploi du comique vallésien dans L'Enfant. Il montre que Vallès construit son roman sur le principe de l'échappatoire : chaque proposition avancée par le narrateur se ménage toujours une sortie de secours. Cette technique du « faux-fuyant » révèle une esthétique double qui tend simultanément vers la littérature engagée et vers l'autonomie, où le détail inutile tourne en dérision le contenu idéologique. L'ambition de Vallès a été de découvrir un tragique qui soit capable de révéler l'envers grotesque de l'histoire contemporaine
Deterministic Approximation Algorithms for Ranking and Clustering Problems
Deterministic Approximation Algorithms for Ranking and Clustering Problem
Perioperative brain functioning:Effects of anesthesia on neurometabolism, cognition and sleep-wake timing
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