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Topic: Acyclic coloring


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In the News (Sat 19 Dec 09)

  
  Acyclic coloring
In graph theory, an acyclic coloring is a (proper) vertex coloring in which every 2-chromatic subgraph is acyclic.
The acyclic chromatic number A(G) of a graph G is the least number of colors needed in any acyclic coloring of G.
Acyclic coloring is often associated with graphs embedded on non-plane surfaces.
www.xasa.com /wiki/en/wikipedia/a/ac/acyclic_coloring.html   (213 words)

  
 Graph coloring
In graph theory, graph coloring is an assignment of "colors", almost always taken to be consecutive integers starting from 1 without loss of generality, to certain objects in a graph.
Graph coloring is not to be confused with graph labeling, which is an assignment of labels, usually also in the form of numbers, to vertices or edges.
A coloring with k colors is called a (proper) k-coloring and is equivalent to the problem of partitioning the vertex set into k independent set s.
www.nebulasearch.com /encyclopedia/article/Graph_coloring.html   (885 words)

  
 Graph coloring - the free encyclopedia   (Site not responding. Last check: 2007-11-01)
For example, anedge coloring of a graph is just the vertex coloring of its line graph.Likewise, a face coloring of a planar graphis just the vertex coloring of its (planar) dual.However, to keep things in their perspective, non-vertex coloring problems are usually stated and studied as are.
Graph coloring is not to be confused with graph labeling, which isan assignment of labels, usually also in the form of numbers, to vertices or edges.
The problem of coloring a graphhas found a number of applications such as scheduling, register allocation in a microprocessor, frequency assignmentin mobile radios, and pattern matching.
www.free-web-encyclopedia.com /default.asp?t=Graph_coloring_problem   (961 words)

  
 Graph coloring - the free encyclopedia   (Site not responding. Last check: 2007-11-01)
In graphtheory, graph coloring is an assignment of"colors", almost always taken to be consecutive integersstarting from 1 without loss of generality, to certain objects in agraph.
Graph coloring is not to be confused with graph labeling,which is an assignment of labels, usually also in the formof numbers, to vertices or edges.
The problem of coloring agraph has found a number of applications such as scheduling, registerallocation in a microprocessor, frequencyassignment in mobile radios, and patternmatching.
www.the-free-web-encyclopedia.com /default.asp?t=Graph_coloring   (864 words)

  
 Graph coloring - LearnThis.Info Enclyclopedia   (Site not responding. Last check: 2007-11-01)
A coloring with k colors is called a (proper) k-coloring and is equivalent to the problem of partitioning the vertex set into k independent sets.
The problem of coloring a graph has found a number of applications such as scheduling, register allocation in a microprocessor, frequency assignment in mobile radios, and pattern matching.
Two colorings of G will be considered different if at least one of the labeled points is assigned a different color.Then, it can be shown that will be a polynomial in.
encyclopedia.learnthis.info /g/gr/graph_coloring.html   (934 words)

  
 Chromatic polynomial
In graph theory, graph coloring is an assignment of "colors", (red, blue and so on, but consecutive integers starting from 1 can be used without loss of generality), to certain objects in a graph.
A coloring using at most k colors is called a (proper) k-coloring and is equivalent to the problem of partitioning the vertex set into k or fewer independent sets.
The problem of coloring a graph has found a number of applications such as scheduling, register allocation in compilers, frequency assignment in mobile radios, and pattern matching.
www.algebra.com /algebra/about/history/Chromatic-polynomial.wikipedia   (1536 words)

  
 Graph coloring   (Site not responding. Last check: 2007-11-01)
In graph theory graph coloring is an assignment of "colors" almost always taken to be consecutive starting from 1 without loss of generality certain objects in a graph.
The problem of coloring a graph found a number of applications such as scheduling register allocation in a microprocessor frequency assignment in mobile radios and pattern matching.
Two colorings of G be considered different if at least one the labeled points is assigned a different it can be shown that f(G t) be a polynomial in t.
www.freeglossary.com /Graph_coloring_algorithm   (1118 words)

  
 Graph coloring algorithm   (Site not responding. Last check: 2007-11-01)
In graph theory, graph coloring is an assignment of"colors", almost always taken to be consecutive integers starting from 1 without loss of generality, to certain objectsin a graph.
Graph coloring is not to be confused with graph labeling, which is an assignment of labels, usually also in the form of numbers, to verticesor edges.
The problem of coloring a graphhas found a number of applications such as scheduling, register allocation in a microprocessor, frequency assignment in mobile radios, and pattern matching.
www.therfcc.org /graph-coloring-algorithm-241954.html   (932 words)

  
 Drawing and Coloring | TutorGig.co.uk Encyclopedia   (Site not responding. Last check: 2007-11-01)
In graph theory, an exact coloring is a Graph coloring proper vertex coloring in which every pair of colors appears on exactly one pair of adjacent vertices.
In graph theory, total coloring is a type of coloring on the vertices and edges of a graph.
In graph theory, an acyclic coloring is a Graph coloring proper vertex coloring in which every Graph coloring 2 chromatic subgraph is Glossary of graph theory acyclic.
www.tutorgig.co.uk /encyclopedia/sencyclo.jsp?keywords=Drawing+and+Coloring   (567 words)

  
 Acyclic   (Site not responding. Last check: 2007-11-01)
The acyclic nucleoside phosphonates HPMPC (cidofovir), PMEA (adefovir), and PMPA (tenofovir) have proved to be...
Acyclic Digraph -- from MathWorld Acyclic Digraph -- from MathWorld An acyclic digraph is a directed graph containing no directed cycles, also known as a directed acyclic graph or a "DAG." Every acyclic digraph has at least one node of...
A proper coloring of the edges of a graph G is called acyclic if there is no 2-colored cycle.
shortestpathalgorithm.mistpath.com /acyclic   (762 words)

  
 CU CSCI Thesis Defense - Skulrattanakulchai (2002-2003)
A proper coloring of a graph is a partition of its elements in such a way that no two adjacent or incident elements belong to the same set in the partition.
It is a vertex coloring, an edge coloring, or a total coloring, according as the elements to be partitioned are the vertices alone, the edges alone, or both the vertices and edges, respectively.
A list coloring is a proper coloring subject to an extra condition that a color to be assigned to an element must come from that element's set (``list'') of colors priorly associated with that element as part of the input.
www.cs.colorado.edu /events/defenses/2002-2003/skulrattanakulchai.html   (371 words)

  
 Graph Theory White Pages: Borodin, Oleg V.   (Site not responding. Last check: 2007-11-01)
Acyclic colouring of 1-planar graphs [MR1760727 (2001b:05077) ].
Acyclic colourings of planar graphs with large girth.
The structure of neighborhoods of an edge in planar graphs and the simultaneous coloring of vertices, edges and faces.
www1.cs.columbia.edu /~sanders/graphtheory/people/random.cgi?Borodin,+Oleg+V.   (706 words)

  
 Acyclic - Qwika
Acyclic coloring In graph theory, an acyclic coloring is a (proper) vertex coloring in which every 2-chromatic subgraph is acyclic.
Directed acyclic graph In théorie of the graphs, one directed acyclic graph (in English directed acyclic graph or DAG) identifies one graphe which...
Acyclic deterministic finite automaton Acyclic deterministic finite automata (ADFA) are deterministic finite...
www.qwika.com /find/Acyclic   (407 words)

  
 Graph coloring
In general, techniques for graph coloring concentrate on finding the least number of colors needed to color the graph, called its chromatic number χ.
The corresponding decision problem(Is there a coloring which uses at most k colors?) is NP-complete.
Two colorings of G will be considered different if at least one of the labeled points is assigned a different color.Then, it can be shown that f(G,t) will be a polynomial in t.
www.askfactmaster.com /Graph_coloring   (1121 words)

  
 Encyclopedia entries starting with ACY
Acyclic can refer to: aliphatic compound, an open hydrocarbon chaindirected acyclic graph, a graph which does not contain any path passing twice by the same nodea chain complex in which all homology groups are zero This is a [disambiguationdisambiguation] page: a list of articles associate..
The acyclic chromatic number A(G) of a graph G is the least number of colors needed in any acyclic coloring of G. Some properties of A(G): A(G) ≤ 2 if and only if G is acyclic.A(G)..
In mathematics, in the field of homological algebra, given an abelian category [\mathcal] having enough injectives and an additive (covariant) functor [F :\mathcal\to\mathcal], an acyclic object with respect to [F], or simply an [F]-acyclic object, is an..
encycl.opentopia.com /A/AC/ACY   (1043 words)

  
 Graph coloring
A 3-coloring suits this graph, but fewer colors would result in adjacent verticies of the same color.
Finding the minimum number of colors is [[NP-hard.]] In graph theory, graph coloring is an assignment of "colors", almost always taken to be consecutive integers starting from 1 without loss of generality, to certain objects in a graph.
The following is one of the few results about infinite graph coloring: :If all finite subgraphs of an infinite graph G are k-colorable, then so is G. (de Bruijn, Erdős 1951) A method to calculate the chromatic number is using the chromatic polynomial
www.keywordmage.net /gr/graph-coloring.html   (988 words)

  
 Dogpile - Web Search: acyclic
Acyclic or cyclic, saturated or unsaturated carbon compounds,...
Acyclic branched or unbranched hydrocarbons having the general formula CnH2n+2,...
acyclic graph is often called a DAG for...
www.dogpile.com /info.dogpl/search/web/acyclic   (224 words)

  
 Two Novel Evolutionary Formulations of the Graph Coloring Problem (ResearchIndex)   (Site not responding. Last check: 2007-11-01)
The first formulation is based on the relationship that exists between a graph's chromatic number and its acyclic orientations.
It views such orientations as individuals and evolves them with the aid of evolutionary operators that are very heavily based on the structure of the graph and its acyclic orientations.
7 Acyclic orientations of a graph and chromatic and independen..
citeseer.ist.psu.edu /479842.html   (723 words)

  
 [Abstract] Self-Stabilizing Acyclic Colorings of Graphs
An acyclic coloring of a graph G is a coloring of the vertices of G such that the vertices with the same color in G induces an acyclic subgraph.
The first algorithm we proposed needs 2 colors for a complete bipartite graph, or less than 1+D/2 colors for a general graph, where D is the degree of G. Both graphs must be acyclic oriented in advance.
In some special acyclic orientation, it needs only 3 colors for a planar graph, or a K3,3-free or K5-free graph.
www.actapress.com /Abstract.aspx?paperId=16641   (135 words)

  
 Acyclic coloring   (Site not responding. Last check: 2007-11-01)
Some properties of A(G): # A(G) ≤ 2 if and only if G is acyclic.
(Kostochka 1978) A milestone in the study of acyclic coloring is the following affirmitive answer to a conjecture of Grünbaum: Theorem.
(Stein 1970, 1971) Acyclic coloring is often associated with graphs embedded on non-plane surfaces.
www.serebella.com /encyclopedia/article-Acyclic_coloring.html   (290 words)

  
 Efficiently Computing Vertex Arboricity of Planar Graphs (ResearchIndex)   (Site not responding. Last check: 2007-11-01)
Abstract: Acyclic-coloring of a graph G = (V; E) is a partitioning of V, such that the induced subgraph of each partition is acyclic.
The minimum number of such partitions of V is defined as the vertex arboricity of G. An O(n) algorithm (n = jV j) for acyclic-coloring of planar graphs with 3 colors is presented.
7 Acyclic colorings of planar graphs (context) - Goddard - 1991
citeseer.ifi.unizh.ch /425380.html   (324 words)

  
 Graph coloring
Let us denote by the number of different colorings of a labeled graph G from colors.
rank coloring - if two vertices have the same color i, then every path between them contain a vertex with color greater then i.
Graph Coloring Page by Joseph Culberson (graph coloring programs)
www.xasa.com /wiki/en/wikipedia/g/gr/graph_coloring.html   (1064 words)

  
 Reviews.com   (Site not responding. Last check: 2007-11-01)
into subsets is called a proper coloring if no two adjacent vertices belong to the same subset (for example, are assigned the same color).
In all cases, they provide a coloring scheme (similar to that described above for acyclic colorings), which achieves the stated bound.
The authors also establish a lower bound for the number of colors required for an acyclic coloring of any graph and make use of it in their estimates.
www.ratings.info /review/review_reviewprint.cfm?review_id=128300   (259 words)

  
 Ac   (Site not responding. Last check: 2007-11-01)
Acyclic can mean any of the following: *In chemistry, an ''acyclic'' compound is a hydrocarbon compound having an open chain.
In graph theory, an '''acyclic coloring''' is a Graph coloring(proper) vertex coloring in which every Graph coloring2-chromatic subgraph is Glossary of graph theoryacyclic.
The '''acyclic chromatic number''' A(''G'') of a graph ''G'' is
xml.gateserver.net /Topicsbycategory.aspx?catid=31&command=nav&search=&name&page=44   (672 words)

  
 Fertin
is a coloring of its vertices such that: (i) no two neighbors in
is the least number of colors necessary to acyclically color
, we also show that any graph of maximum degree 5 can be acyclically colored with at most 9 colors, and give a linear time algorithm to achieve this bound.
www.dmtcs.org /dmtcs-ojs/index.php/proceedings/article/view/dmAE0175/1213   (363 words)

  
 acyclic definition from the Dictionary of Words Online
acyclic adj 1: botany; not cyclic; especially having parts arranged in spirals rather than whorls ant: cyclic 2: chemistry; not cyclic; having an open chain structure syn: open-chain ant: cyclic see also: cyclic open-chain
...Acyclic can mean any of the following: *In chemistry, an acyclic.
...An upward plane drawing of a directed acyclic graph is a plane drawing...
www.dictionaryofwords.com /acyclic_pag1.html   (230 words)

  
 SIAM: First SIAM Workshop on Combinatorial Scientific Computing
Working in the U.K. in the 1970s, Alan Curtis, Mike Powell, and John Reid reduced the number of (vector) function evaluations needed to compute sparse Jacobians by packing together structurally orthogonal columns (a group of columns is structurally orthogonal when the nonzeros are in disjoint (non-overlapping) rows).
A distance-k coloring of a graph corresponds to a coloring of its vertices such that every vertex at a distance of at most k edges from a given vertex is assigned a color distinct from that vertex's color.
In an acyclic coloring of a graph, every vertex is assigned a color distinct from that of any of its neighboring vertices; in addition, every cycle has vertices with at least three distinct colors.
www.siam.org /news/news.php?id=280   (1630 words)

  
 Graph Coloring for Computing Derivatives
Depending on whether the matrix of interest is Jacobian (nonsymmentric) or Hessian (symmetric), and on the specifics of the computational techniques employed, several partitioning problems can be identified.
We formulate these as graph coloring problems, enabling us to analyze the complexity of the problems, and to design and implement effective algorithms for solving them.
In this work, we integrate existing coloring formulations with new ones, design more efficient algorithms for problems that have been studied earlier, and introduce graph models for new matrix computation problems that arise in preconditioning.
www.cs.odu.edu /~assefaw/coloringpage   (314 words)

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