Mr. Paint and Mrs. Correct

We introduce a coloring game on graphs, in which each vertex $v$ of a graph $G$ owns a stack of $\ell_v{-}1$ erasers. In each round of this game the first player Mr. Paint takes an unused color, and colors some of the uncolored vertices. He might color adjacent vertices with this color – something which is considered "incorrect". However, Mrs. Correct is positioned next to him, and corrects his incorrect coloring, i.e., she uses up some of the erasers – while stocks (stacks) last – to partially undo his assignment of the new color. If she has a winning strategy, i.e., she is able to enforce a correct and complete final graph coloring, then we say that $G$ is $\ell$-paintable . Our game provides an adequate game-theoretic approach to list coloring problems. The new concept is actually more general than the common setting with lists of available colors. It could have applications in time scheduling, when the available time slots are not known in advance. We give an example that shows that the two notions are not equivalent; $\ell$-paintability is stronger than $\ell$-list colorability . Nevertheless, many deep theorems about list colorability remain true in the context of paintability. We demonstrate this fact by proving strengthened versions of classical list coloring theorems. Among the obtained extensions are paintability versions of Thomassen's, Galvin's and Shannon's Theorems.

[1]  Tommy R. Jensen,et al.  Graph Coloring Problems , 1994 .

[2]  R.K. Guy,et al.  On numbers and games , 1978, Proceedings of the IEEE.

[3]  Carsten Thomassen,et al.  Every Planar Graph Is 5-Choosable , 1994, J. Comb. Theory B.

[4]  Fred Galvin,et al.  The List Chromatic Index of a Bipartite Multigraph , 1995, J. Comb. Theory B.

[5]  Alexandr V. Kostochka,et al.  List Edge and List Total Colourings of Multigraphs , 1997, J. Comb. Theory B.

[6]  Zsolt Tuza,et al.  New trends in the theory of graph colorings: Choosability and list coloring , 1997, Contemporary Trends in Discrete Mathematics.

[7]  Uwe Schauz,et al.  A Paintability Version of the Combinatorial Nullstellensatz, and List Colorings of k-partite k-uniform Hypergraphs , 2010, Electron. J. Comb..

[8]  deXuding Zhu Game Chromatic Number of Graphs , 1998 .

[10]  Noga Alon,et al.  Colorings and orientations of graphs , 1992, Comb..

[11]  Keith Walker Surveys in combinatorics, 1993 , 1993 .

[12]  Uwe Schauz,et al.  Flexible Color Lists in Alon and Tarsi's Theorem, and Time Scheduling with Unreliable Participants , 2010, Electron. J. Comb..

[13]  N. Alon Restricted colorings of graphs , 1993 .

[14]  Alexandr V. Kostochka,et al.  List edge chromatic number of graphs with large girth , 1992, Discret. Math..

[15]  Xuding Zhu,et al.  A bound for the game chromatic number of graphs , 1999, Discret. Math..

[16]  Zsolt Tuza,et al.  Graph colorings with local constraints - a survey , 1997, Discuss. Math. Graph Theory.

[17]  Uwe Schauz,et al.  Algebraically Solvable Problems: Describing Polynomials as Equivalent to Explicit Solutions , 2008, Electron. J. Comb..

[18]  Xuding Zhu,et al.  The Map-Coloring Game , 2007, Am. Math. Mon..