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42
Hausdorff core of a one reflex vertex polygon
 Algorithms Data Structures
, 2009
"... In this paper we present a polynomial time algorithm for computing a Hausdorff core of a polygon with a single reflex vertex. A Hausdorff core of a polygon P is a convex polygon Q contained inside P which minimizes the Hausdorff distance between P and Q. Our algorithm essentially consists of rotatin ..."
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Cited by 2 (1 self)
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In this paper we present a polynomial time algorithm for computing a Hausdorff core of a polygon with a single reflex vertex. A Hausdorff core of a polygon P is a convex polygon Q contained inside P which minimizes the Hausdorff distance between P and Q. Our algorithm essentially consists
List Homomorphisms to Reflexive Graphs
, 1998
"... Let H be a fixed graph. We introduce the following list homomorphism problem: Given an input graph G and for each vertex v of G a ``list' ' L(v) V(H), decide whether or not there is a homomorphism f:G H such that f(v)#L(v) for each v#V(G). We discuss this problem primarily in the context o ..."
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Cited by 57 (24 self)
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of reflexive graphs, i.e., graphs in which each vertex has a loop. We give a polynomial time algorithm to solve the problem when H is an interval graph and prove that when H is not an interval graph the problem is NPcomplete. If the lists are restricted to induce connected subgraphs of H, we give a polynomial
A vertexface assignment for plane graphs
"... For any planar straight line graph (Pslg), there is a vertexface assignment such that every vertex is assigned to at most two adjacent faces, and every face is assigned to all its reflex vertices and one more incident vertex. The existence of such an assignment implies, in turn, that any Pslg can b ..."
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Cited by 3 (0 self)
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For any planar straight line graph (Pslg), there is a vertexface assignment such that every vertex is assigned to at most two adjacent faces, and every face is assigned to all its reflex vertices and one more incident vertex. The existence of such an assignment implies, in turn, that any Pslg can
A.: Vertex Guards in a Subclass of Orthogonal Polygons
 International Journal of Computer Science and Network Security (IJCSNS
, 2006
"... Summary We call grid nogon each nvertex orthogonal simple polygon, with no collinear edges, that may be placed in a ) 2 / ( ) 2 / ( n n × unit square grid. In this paper we consider the Minimum Vertex Guard problem for this class of orthogonal polygons. As a step for the resolution of this genera ..."
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Cited by 1 (1 self)
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Summary We call grid nogon each nvertex orthogonal simple polygon, with no collinear edges, that may be placed in a ) 2 / ( ) 2 / ( n n × unit square grid. In this paper we consider the Minimum Vertex Guard problem for this class of orthogonal polygons. As a step for the resolution
List Homomorphisms to reflexive digraphs
"... We study list homomorphism problems LHOM(H) for the class of reflexive digraphs H (digraphs in which each vertex has a loop). These problems have been intensively studied in the case of undirected graphs H, and appear to be more difficult for digraphs. However, it is known that each problem LHOM(H ..."
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Cited by 3 (0 self)
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We study list homomorphism problems LHOM(H) for the class of reflexive digraphs H (digraphs in which each vertex has a loop). These problems have been intensively studied in the case of undirected graphs H, and appear to be more difficult for digraphs. However, it is known that each problem L
Minimum Cost Homomorphisms to reflexive digraphs
 8th Latin American Theoretical Informatics (LATIN), Rio de Janeiro, Brazil
"... For digraphs G and H, a homomorphism of G to H is a mapping f: V (G)→V (H) such that uv ∈ A(G) implies f(u)f(v) ∈ A(H). If moreover each vertex u ∈ V (G) is associated with costs ci(u), i ∈ V (H), then the cost of a homomorphism f is u∈V (G) c f(u)(u). For each fixed digraph H, the minimum cost hom ..."
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Cited by 15 (8 self)
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are known. We focus on the minimum cost homomorphism problem for reflexive digraphs H (every vertex of H has a loop). It is known that the problem MinHOM(H) is polynomial time solvable if the digraph H has a MinMax ordering, i.e., if its vertices can be linearly ordered by < so that i < j, s < r
Telling convex from reflex allows to map a polygon
"... We consider the exploration of a simple polygon P by a robot that moves from vertex to vertex along edges of the visibility graph of P. The visibility graph has a vertex for every vertex of P and an edge between two vertices if they see each other, i.e. if the line segment connecting them lies insid ..."
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Cited by 2 (1 self)
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inside P entirely. While located at a vertex, the robot is capable of ordering the vertices it sees in counterclockwise order as they appear on the boundary, and for every two such vertices, it can distinguish whether the angle between them is convex ( ≤ π) or reflex (> π). Other than that, distant
AMapping simple polygons: The power of telling convex from reflex
"... We consider the exploration of a simple polygon P by a robot that moves from vertex to vertex along edges of the visibility graph of P. The visibility graph has a vertex for every vertex of P and an edge between two vertices if they see each other, i.e., if the line segment connecting them lies insi ..."
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Cited by 1 (1 self)
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inside P entirely. While located at a vertex, the robot is capable of ordering the vertices it sees in counterclockwise order as they appear on the boundary, and for every two such vertices, it can distinguish whether the angle between them is convex ( ≤ pi) or reflex (> pi). Other than that, distant
: //pefmath.etf.bg.ac.yu ON A CLASS OF TRICYCLIC REFLEXIVE
"... A simple graph is reflexive if the second largest eigenvalue of its (0, 1) adjacency matrix does not exceed 2. A graph is a cactus, or a treelike graph, if any pair of its cycles (circuits) has at most one common vertex. The subject of this paper is the class of tricyclic cactuses in which the cent ..."
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A simple graph is reflexive if the second largest eigenvalue of its (0, 1) adjacency matrix does not exceed 2. A graph is a cactus, or a treelike graph, if any pair of its cycles (circuits) has at most one common vertex. The subject of this paper is the class of tricyclic cactuses in which
Shooting permanent rays among disjoint polygons
 in the plane, in: Proc. 25th SCG, 2009, ACM
"... We present a data structure for ray shootingandinsertion in the free space among disjoint polygonal obstacles with a total of n vertices in the plane, where each ray starts at the boundary of some obstacle. The portion of each query ray between the starting point and the first obstacle hit is inse ..."
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Cited by 3 (2 self)
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the expected runtime of Patersen and Yao’s classical randomized autopartition algorithm for n disjoint line segments to O(n log 2 n). (2) If we are given disjoint polygonal obstacles with a total of n vertices in the plane, a permutation of the reflex vertices, and a halfline at each reflex vertex
Results 1  10
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