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Electronic Colloquium on Computational Complexity

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REPORTS > KEYWORD > PLANAR GRAPHS:
Reports tagged with planar graphs:
TR99-030 | 9th July 1999
Meena Mahajan, P R Subramanya, V Vinay

A Combinatorial Algorithm for Pfaffians

The Pfaffian of an oriented graph is closely linked to
Perfect Matching. It is also naturally related to the determinant of
an appropriately defined matrix. This relation between Pfaffian and
determinant is usually exploited to give a fast algorithm for
computing Pfaffians.

We present the first completely combinatorial algorithm for ... more >>>


TR00-051 | 14th July 2000
Marek Karpinski, Miroslaw Kowaluk, Andrzej Lingas

Approximation Algorithms for MAX-BISECTION on Low Degree Regular Graphs and Planar Graphs

The max-bisection problem is to find a partition of the vertices of a
graph into two equal size subsets that maximizes the number of edges with
endpoints in both subsets.
We obtain new improved approximation ratios for the max-bisection problem on
the low degree $k$-regular graphs for ... more >>>


TR00-064 | 29th August 2000
Klaus Jansen, Marek Karpinski, Andrzej Lingas

A Polynomial Time Approximation Scheme for MAX-BISECTION on Planar Graphs

The Max-Bisection and Min-Bisection are the problems of finding
partitions of the vertices of a given graph into two equal size subsets so as
to maximize or minimize, respectively, the number of edges with exactly one
endpoint in each subset.
In this paper we design the first ... more >>>


TR05-148 | 6th December 2005
Eric Allender, Samir Datta, Sambuddha Roy

The Directed Planar Reachability Problem

Revisions: 1

We investigate the s-t-connectivity problem for directed planar graphs, which is hard for L and is contained in NL but is not known to be complete. We show that this problem is logspace-reducible to its complement, and we show that the problem of searching graphs of genus 1 reduces to ... more >>>


TR05-149 | 7th December 2005
Eric Allender, David Mix Barrington, Tanmoy Chakraborty, Samir Datta, Sambuddha Roy

Grid Graph Reachability Problems

Revisions: 1

We study the complexity of restricted versions of st-connectivity, which is the standard complete problem for NL. Grid graphs are a useful tool in this regard, since
* reachability on grid graphs is logspace-equivalent to reachability in general planar digraphs, and
* reachability on certain classes of grid graphs gives ... more >>>


TR08-060 | 10th April 2008
James R. Lee, Prasad Raghavendra

Coarse Differentiation and Multi-flows in Planar Graphs

We show that the multi-commodity max-flow/min-cut gap for series-parallel graphs can be as bad as 2, matching a recent upper bound by Chakrabarti.et.al for this class, and resolving one side of a conjecture of Gupta, Newman, Rabinovich, and Sinclair.

This also improves the largest known gap for planar graphs ... more >>>


TR09-024 | 26th February 2009
Raghav Kulkarni

On the Power of Isolation in Planar Structures

The purpose of this paper is to study the deterministic
{\em isolation} for certain structures in directed and undirected
planar graphs.
The motivation behind this work is a recent development on this topic. For example, \cite{btv07} isolate a directed path in planar graphs and
\cite{dkr08} isolate a perfect matching in ... more >>>


TR11-148 | 3rd November 2011
Rohit Gurjar, Arpita Korwar, Jochen Messner, Simon Straub, Thomas Thierauf

Planarizing Gadgets for Perfect Matching do not Exist

To compare the complexity of the perfect matching problem for general graphs with that for planar graphs, one might try to come up with a reduction from the perfect matching problem to the planar perfect matching problem.
The obvious way to construct such a reduction is via a {\em planarizing ... more >>>


TR18-211 | 3rd December 2018
Kshitij Gajjar, Jaikumar Radhakrishnan

Parametric Shortest Paths in Planar Graphs

We construct a family of planar graphs $(G_n: n\geq 4)$, where $G_n$ has $n$ vertices including a source vertex $s$ and a sink vertex $t$, and edge weights that change linearly with a parameter $\lambda$ such that, as $\lambda$ increases, the cost of the shortest path from $s$ to $t$ ... more >>>




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