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  1.  30
    A P‐Completeness Result for Visibility Graphs of Simple Polygons.Jana Dietel & Hans-Dietrich Hecker - 2000 - Mathematical Logic Quarterly 46 (3):361-375.
    For each vertex of a simple polygon P an integer valued weight is given. We consider the path p1, p2, ..., pk in P which is created according to the following strategy: p1 is a designated start vertex s and pi+1 is obtained by choosing the vertex with smallest weight among all vertices visible from pi and different from p1, p2, ..., pi. If there is no such vertex the path is finished. This path is called geometric lexicographic dead end (...)
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  2.  12
    Quadrilaterizing an Orthogonal Polygon in Parallel.Jana Dietel & Hans-Dietrich Hecker - 1998 - Mathematical Logic Quarterly 44 (1):50-68.
    We consider the problem of quadrilaterizing an orthogonal polygon P, that is to decompose P into nonoverlapping convex quadrangles without adding new vertices. In this paper we present a CREW-algorithm for this problem which runs in O time using Θ processors if the rectangle decomposition of P is given, and Θ processors if not. Furthermore we will show that the latter result is optimal if the polygon is allowed to contain holes.
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  3.  3
    Allgemeine Trennbarkeitsbegriffe bei Metamathematischen Untersuchungen.Hans-Dietrich Hecker - 1971 - Mathematical Logic Quarterly 17 (1):205-217.
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  4.  20
    Allgemeine Trennbarkeitsbegriffe bei Metamathematischen Untersuchungen.Hans-Dietrich Hecker - 1971 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 17 (1):205-217.
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  5.  21
    Abstrakte Tempomasze Und Speed-Up-Theoremea Für Enumerationen Rekursiv-Aufzählbarer Mengen.Hans-Dietrich Hecker - 1984 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 30 (17-18):269-281.
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  6.  14
    Das Kompressionstheorem Für Tempomasze.Hans-Dietrich Hecker - 1984 - Mathematical Logic Quarterly 30 (17‐18):283-288.
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  7.  20
    Das Kompressionstheorem Für Tempomasze.Hans-Dietrich Hecker - 1984 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 30 (17-18):283-288.
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  8.  8
    Definierbarkeit und unentscheidbarkeit.Hans-Dietrich Hecker - 1969 - Mathematical Logic Quarterly 15 (6):81-84.
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  9.  19
    Definierbarkeit und unentscheidbarkeit.Hans-Dietrich Hecker - 1969 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 15 (6):81-84.
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  10.  6
    Rekursive Untrennbarkeit Bei Elementaren Theorien.Hans-Dietrich Hecker - 1971 - Mathematical Logic Quarterly 17 (1):443-463.
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  11.  20
    Rekursive Untrennbarkeit Bei Elementaren Theorien.Hans-Dietrich Hecker - 1971 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 17 (1):443-463.
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  12.  14
    Zur Programmkomplexität Rekursiv Aufzählbarer Mengen.Hans-Dietrich Hecker - 1976 - Mathematical Logic Quarterly 22 (1):239-244.
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  13.  22
    Zur Programmkomplexität Rekursiv Aufzählbarer Mengen.Hans-Dietrich Hecker - 1976 - Zeitschrift fur mathematische Logik und Grundlagen der Mathematik 22 (1):239-244.
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  14.  12
    Two NP‐Hard Art‐Gallery Problems for Ortho‐Polygons.Dietmar Schuchardt & Hans-Dietrich Hecker - 1995 - Mathematical Logic Quarterly 41 (2):261-267.
    D. T. Lee and A. K. Lin [2] proved that VERTEX-GUARDING and POINT-GUARDING are NP-hard for simple polygons. We prove that those problems are NP-hard for ortho-polygons, too.
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  15.  12
    Variants of Visibility and Their Complexity.Dietmar Schuchardt & Hans-Dietrich Hecker - 1998 - Mathematical Logic Quarterly 44 (4):522-528.
    First we give an overview about variants of visibility and related problems. Then we prove that some guarding and covering problems are NP-hard for ortho-polygons with holes, using a so-called vertex cover technique.
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  16.  7
    Minimizing the Size of Vertexlights in Simple Polygons.Andreas Spillner & Hans-Dietrich Hecker - 2002 - Mathematical Logic Quarterly 48 (3):447-458.
    We show that given a simple Polygon P it is NP-hard to determine the smallest α ∈ [0, π] such that P can be illuminated by α-vertexlights, if we place exactly one α-vertexlight in each vertex of P.
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