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  1. No Access

    Chapter and Conference Paper

    On Half Guarding Polygons

    Given a polygon P and a set of potential guard locations \(G \in P\) G ...

    Erik Krohn, Alex Pahlow, Zhongxiu Yang in Combinatorial Optimization and Applications (2024)

  2. No Access

    Chapter and Conference Paper

    Guarding Polyominoes Under k-Hop Visibility

    We study the Art Gallery Problem under k-hop visibility in polyominoes. In this visibility model, two unit squares of a polyomino can see each other if and only if the shortest path between the respective vertice...

    Omrit Filtser, Erik Krohn, Bengt J. Nilsson in LATIN 2024: Theoretical Informatics (2024)

  3. No Access

    Chapter and Conference Paper

    On Vertex Guarding Staircase Polygons

    In this paper, we consider the variant of the art gallery problem where the input polygon is a staircase polygon. Previous works on this problem gave a 2-approximation for point guarding a staircase polygon (w...

    Matt Gibson-Lopez, Erik Krohn, Bengt J. Nilsson in LATIN 2022: Theoretical Informatics (2022)

  4. No Access

    Chapter and Conference Paper

    On the Complexity of Half-Guarding Monotone Polygons

    We consider a variant of the art gallery problem where all guards are limited to seeing to the right inside a monotone polygon. We call such guards: half-guards. We provide a polynomial-time approximation for ...

    Hannah Miller Hillberg, Erik Krohn, Alex Pahlow in LATIN 2022: Theoretical Informatics (2022)

  5. No Access

    Chapter and Conference Paper

    A Characterization of Visibility Graphs for Pseudo-polygons

    In this paper, we give a characterization of the visibility graphs of pseudo-polygons. We first identify some key combinatorial properties of pseudo-polygons, and we then give a set of five necessary condition...

    Matt Gibson, Erik Krohn, Qing Wang in Algorithms - ESA 2015 (2015)

  6. No Access

    Chapter and Conference Paper

    The VC-Dimension of Visibility on the Boundary of a Simple Polygon

    In this paper, we prove that the VC-Dimension of visibility on the boundary of a simple polygon is exactly 6. Our result is the first tight bound for any variant of the VC-Dimension problem regarding simple po...

    Matt Gibson, Erik Krohn, Qing Wang in Algorithms and Computation (2015)

  7. Article

    Open Access

    Improved Approximations for Guarding 1.5-Dimensional Terrains

    We present a 4-approximation algorithm for the problem of placing the fewest guards on a 1.5D terrain so that every point of the terrain is seen by at least one guard. This improves on the previous best approx...

    Khaled Elbassioni, Erik Krohn, Domagoj Matijević, Julián Mestre in Algorithmica (2011)

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    Article

    On Metric Clustering to Minimize the Sum of Radii

    Given an n-point metric (P,d) and an integer k>0, we consider the problem of covering P by k balls so as to minimize the sum of the radii of the balls. We present a randomized algorithm that runs in n ...

    Matt Gibson, Gaurav Kanade, Erik Krohn, Imran A. Pirwani in Algorithmica (2010)

  9. No Access

    Chapter and Conference Paper

    An Approximation Scheme for Terrain Guarding

    We obtain a polynomial time approximation scheme for the terrain guarding problem improving upon several recent constant factor approximations. Our algorithm is a local search algorithm inspired by the recent ...

    Matt Gibson, Gaurav Kanade, Erik Krohn in Approximation, Randomization, and Combinat… (2009)

  10. No Access

    Chapter and Conference Paper

    On Metric Clustering to Minimize the Sum of Radii

    Given an n-point metric (P,d) and an integer k > 0, we consider the problem of covering P by k balls so as to minimize the sum of the radii of the balls. We present a randomized algorithm that runs in n ...

    Matt Gibson, Gaurav Kanade, Erik Krohn, Imran A. Pirwani in Algorithm Theory – SWAT 2008 (2008)