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In geometric graph theory, the Hadwiger–Nelson problem, named after Hugo Hadwiger and Edward Nelson, asks for the minimum number of colors required to color the plane such that no two points at distance 1 from each other have the same color. The answer is unknown, but has been narrowed down to one of the numbers 5, 6 or 7.
BigGantt utilizes a user's web browser.The app displays Jira tasks on a timeline in the form of colored bars of various lengths. Compared to the original 1910s idea of a bar chart devised by Henry Gantt, BigGantt adds contemporary functionalities, i.e. dependencies between tasks on the chart (arrows that link two tasks and change color from green to red when a dependency becomes "impossible ...
The problem of edge coloring has also been studied in the distributed model. Panconesi & Rizzi (2001) achieve a (2Δ − 1)-coloring in O(Δ + log * n) time in this model. The lower bound for distributed vertex coloring due to Linial (1992) applies to the distributed edge coloring problem as well.
The De Bruijn–Erdős theorem also applies directly to hypergraph coloring problems, where one requires that each hyperedge have vertices of more than one color. As for graphs, a hypergraph has a k {\displaystyle k} -coloring if and only if each of its finite sub-hypergraphs has a k {\displaystyle k} -coloring. [ 20 ]
In graph theory, the Erdős–Faber–Lovász conjecture is a problem about graph coloring, named after Paul Erdős, Vance Faber, and László Lovász, who formulated it in 1972. [1] It says: If k complete graphs , each having exactly k vertices, have the property that every pair of complete graphs has at most one shared vertex, then the union ...
For a graph G, let χ(G) denote the chromatic number and Δ(G) the maximum degree of G.The list coloring number ch(G) satisfies the following properties.. ch(G) ≥ χ(G).A k-list-colorable graph must in particular have a list coloring when every vertex is assigned the same list of k colors, which corresponds to a usual k-coloring.
Finding ψ(G) is an optimization problem.The decision problem for complete coloring can be phrased as: . INSTANCE: a graph G = (V, E) and positive integer k QUESTION: does there exist a partition of V into k or more disjoint sets V 1, V 2, …, V k such that each V i is an independent set for G and such that for each pair of distinct sets V i, V j, V i ∪ V j is not an independent set.
The vertex coloring game was introduced in 1981 by Steven Brams as a map-coloring game [1] [2] and rediscovered ten years after by Bodlaender. [3] Its rules are as follows: Alice and Bob color the vertices of a graph G with a set k of colors. Alice and Bob take turns, coloring properly an uncolored vertex (in the standard version, Alice begins).