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New for: D1, D2

What and Who

How to find optimal fractional dicycle packing and cover in polynomial time

Zeev Nutov
Max-Planck-Institut für Informatik - AG 1
AG1 Advanced Mini-Course
AG 1, AG 2  
AG Audience
English

Date, Time and Location

Thursday, 9 September 99
13:30
60 Minutes
MPI
024
Saarbrücken

Abstract

Let $D=(V,A)$ be a digraph with nonnegative weights $w(e)$ on its arcs.

The minimum dicycle cover problem is to find nonnegative numbers $x_e$,
such that $\sum {x_e: e \in C} \geq 1$ for every dicycle $C$ in $D$,
and such that $\sum {w(e)x_e: e \in A}$ is as small as possible.
The maximum dicycle packing problem is to find a family $H$ of dicycles
of $D$ and nonnegative numbers $y_C$, $C \in H$, such that
$\sum {y_C: e \in C} \leq w(e)$ for all $e \in A$, and such that
$\sum {y_C: C \in H}$ is as large as possible.
The latter problem is mentioned in the literature as being NP-hard.
We will show that both problems are solvable in strongly polynomial time.

In a subsequent talk, I will consider integral versions of these problems.

Contact

Zeev Nutov
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Tags, Category, Keywords and additional notes

directed graph, fractional dicycle cover and packing, polynomial algorithm.