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Dive into the research topics where Panos Giannopoulos is active.

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Featured researches published by Panos Giannopoulos.


The Computer Journal | 2008

Parameterized Complexity of Geometric Problems

Panos Giannopoulos; Christian Knauer; Sue Whitesides

This paper surveys parameterized complexity results for hard geometric algorithmic problems. It includes fixed-parameter tractable problems in graph drawing, geometric graphs, geometric covering and several other areas, together with an overview of the algorithmic techniques used. Fixed-parameter intractability results are surveyed as well. Finally, we give some directions for future research.


symposium on computational geometry | 2005

Finding the best shortcut in a geometric network

Mohammad Farshi; Panos Giannopoulos; Joachim Gudmundsson

Given a Euclidean graph G in Rd with n vertices and m edges we consider the problem of adding a shortcut such that the stretch factor of the resulting graph is minimized. Currently, the fastest algorithm for computing the stretch factor of a Euclidean graph runs in O(mn+n2 log n) time, resulting in a trivial O(mn3+n4 log n) time algorithm for computing the optimal shortcut. First, we show that a simple modification yields the optimal solution in O(n4) time using O(n2) space. To reduce the running times we consider several approximation algorithms. Our main result is a (2+ε)-approximation algorithm with running time O(nm+n2(log n+1/ε3d)) using O(n2) space.


SIAM Journal on Computing | 2008

Improving the Stretch Factor of a Geometric Network by Edge Augmentation

Mohammad Farshi; Panos Giannopoulos; Joachim Gudmundsson

Given a Euclidean graph


Journal of Complexity | 2012

Hardness of discrepancy computation and ε-net verification in high dimension

Panos Giannopoulos; Christian Knauer; Magnus Wahlström; Daniel Werner

G


International Journal of Computational Geometry and Applications | 2010

COMPUTING GEOMETRIC MINIMUM-DILATION GRAPHS IS NP-HARD

Panos Giannopoulos; Rolf Klein; Christian Knauer; Martin Kutz; Dániel Marx

in


IWPEC'06 Proceedings of the Second international conference on Parameterized and Exact Computation | 2006

On the parameterized complexity of d -dimensional point set pattern matching

Sergio Cabello; Panos Giannopoulos; Christian Knauer

\mathbb{R}^d


european symposium on algorithms | 2005

Matching point sets with respect to the earth mover’s distance

Sergio Cabello; Panos Giannopoulos; Christian Knauer; Günter Rote

with


scandinavian workshop on algorithm theory | 2004

Maximizing the area of overlap of two unions of disks under rigid motion

Mark de Berg; Sergio Cabello; Panos Giannopoulos; Christian Knauer; René van Oostrum; Remco C. Veltkamp

n


Algorithmica | 2016

The Complexity of Separating Points in the Plane

Sergio Cabello; Panos Giannopoulos

vertices and


arXiv: Computational Geometry | 2009

The Parameterized Complexity of Some Geometric Problems in Unbounded Dimension

Panos Giannopoulos; Christian Knauer; Günter Rote

m

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Günter Rote

Free University of Berlin

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Édouard Bonnet

Hungarian Academy of Sciences

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Dániel Marx

Hungarian Academy of Sciences

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Daniel Werner

Free University of Berlin

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Helmut Alt

Free University of Berlin

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