Fixed-parameter tractability and lower bounds for stabbing problems (2009)
Giannopoulos, Panos, Knauer, Christian, Rote, Gunter, Werner, Daniel
We study the following general stabbing problem from a parameterized complexity point of view: Given a set $\mathcal S$ of $n$ translates of an object in $\Rd$, find a set of $k$ lines with the...
Fixed-parameter tractability and lower bounds for stabbing problems (2009)
Giannopoulos, Panos, Knauer, Christian, Rote, Gunter, Werner, Daniel
We study the following general stabbing problem from a parameterized complexity point of view: Given a set $\mathcal S$ of $n$ translates of an object in $\Rd$, find a set of $k$ lines with the...
The parameterized complexity of some geometric problems in unbounded dimension (2009)
Giannopoulos, Panos, Knauer, Christian, Rote, Gunter, Werner, Daniel
We study the parameterized complexity of the following fundamental geometric problems with respect to the dimension $d$: i) Given $n$ points in $\Rd$, compute their minimum enclosing cylinder. ii)...
Sergio Cabello, Panos Giannopoulos, Christian Knauer, Günter Rote
We present an algorithm for the 3-center problem in (R d, L∞), i. e., for finding the smallest side length for 3 cubes that cover a given n-point set in R d, that runs in O(n log n) time for any...
Sergio Cabello, Panos Giannopoulos, Christian Knauer
Abstract We present an algorithm for the 3-center problem in (Rd, L1), i. e., for finding the smallest side length for 3 cubes that cover a given n-point set in Rd, that runs in O(n log n)time for...
doi:10.1093/comjnl/bxm053 Parameterized Complexity of Geometric Problems (2008)
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...
Maximizing the Area of Overlap of two Unions of Disks under Rigid Motion ∗ (2008)
Mark Berg, Sergio Cabello, Panos Giannopoulos, Christian Knauer, René Oostrum, Remco C. Veltkamp
Let A and B be two sets of n resp. m disjoint unit disks in the plane, with m ≥ n. We consider the problem of finding a translation or rigid motion of A that maximizes the total area of overlap...
Nationality: Greek Education (2008)
Dr. Panos Giannopoulos, Name Panos Giannopoulos, Address Freie, Supervisor Assoc, Prof Dr, ...
Thesis: Geometric matching of weighted point sets Project: “Shape Matching Environment ” (NWO)
www.cs.uu.nl Using Transportation Distances for Measuring Melodic Similarity (2008)
Rainer Typke, Panos Giannopoulos, Remco C. Veltkamp, Frans Wiering, René Van Oostrum, Rainer Typke, ...
Most of the existing methods for measuring melodic similarity use one-dimensional textual representations of music notation, so that melodic similarity can be measured by calculating editing...
Parameterized Complexity of Geometric Problems (2008)
Giannopoulos, Panos, Knauer, Christian, Whitesides, Sue
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...
Minimum-dilation tour (and path) is NP-hard (2007)
Panos Giannopoulos, Christian Knauer, Dániel Marx
We prove that computing a minimum-dilation (Euclidean) Hamilton circuit or path on a given set of points in the plane is NP-hard. 1
Finding the best shortcut in a geometric network (2005)
Mohammad Farshi, Panos Giannopoulos, Joachim Gudmundsson
Given a Euclidean graph G in R d 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...
Matching Point Sets with respect to the Earth Mover’s Distance (2005)
Sergio Cabello, Panos Giannopoulos, Christian Knauer, Günter Rote
Let A and B be two sets of m resp. n weighted points in the plane, with m ≤ n. We present (1 + ɛ) and (2+ɛ)-approximation algorithms for the minimum Euclidean Earth Mover’s Distance between A...
Matching Point Sets with respect to the Earth Mover’s Distance (2005)
Sergio Cabello, Panos Giannopoulos, Christian Knauer, Günter Rote
The Earth Mover’s Distance (EMD) between two weighted point sets (point distributions) is a distance measure commonly used in computer vision for color-based image retrieval and shape matching. It...
Finding the best shortcut in a geometric network (2005)
Mohammad Farshi, Panos Giannopoulos, Joachim Gudmundsson
Abstract. Given a Euclidean graph G in R d 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...
Finding the best shortcut in a geometric network (2005)
Mohammad Farshi, Panos Giannopoulos, Joachim Gudmundsson
Given a Euclidean graph G in R d 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...
Matching Point Sets with respect to the Earth Mover’s Distance (2005)
Sergio Cabello, Panos Giannopoulos, Christian Knauer, Günter Rote
Shape matching is a fundamental problem in computer vision: given two shapes A and B, one wants to determine how closely A resembles B, according to some distance measure between the shapes. In order...
Maximizing the Area of Overlap of two (2004)
Unions Of Disks, Mark De Berg, Mark De Berg, Sergio Cabello, Sergio Cabello, Panos Giannopoulos, ...
Let A and B be two sets of n resp. m (m n) disjoint unit disks in the plane. We consider the problem of nding a rigid motion of A that maximizes the total area of its overlap with B. The function...
Using Transportation Distances for Measuring Melodic Similarity (2003)
Rainer Typke Panos, Panos Giannopoulos, Remco C. Veltkamp, Frans Wiering, René Van Oostrum
Most of the existing methods for measuring melodic similarity use one-dimensional textual representations of music notation, so that melodic similarity can be measured by calculating editing...
Using Transportation Distances for Measuring Melodic Similarity (2003)
Rainer Typke, Rainer Typke, Panos Giannopoulos, Panos Giannopoulos, Remco C. Veltkamp, Remco C. Veltkamp, ...
Most of the existing methods for measuring melodic similarity use one-dimensional textual representations of music notation, so that melodic similarity can be measured by calculating editing...
The Area of Overlap of two Unions of Convex Objects under Translation (2003)
Mark De Berg, Panos Giannopoulos, Christian Knauer, Remco C. Veltkamp
Let A and B be two sets of n resp. m disjoint unit discs in the plane, with m n. We consider the problem of nding a translation of A that maximizes the total area of its overlap with B. We rst show...
A Pseudo-Metric for Weighted Point Sets (2002)
Panos Giannopoulos, Remco C. Veltkamp
Abstract. We present a pseudo-metric for weighted point sets. There are numerous situations, for example in the shape description domain, where the individual points in a feature point set have an...