234,147 research outputs found
Defective 3-Paintability of Planar Graphs
A -defective -painting game on a graph is played by two players:
Lister and Painter. Initially, each vertex is uncolored and has tokens. In
each round, Lister marks a chosen set of uncolored vertices and removes one
token from each marked vertex. In response, Painter colors vertices in a subset
of which induce a subgraph of maximum degree at most . Lister
wins the game if at the end of some round there is an uncolored vertex that has
no more tokens left. Otherwise, all vertices eventually get colored and Painter
wins the game. We say that is -defective -paintable if Painter has a
winning strategy in this game. In this paper we show that every planar graph is
3-defective 3-paintable and give a construction of a planar graph that is not
2-defective 3-paintable.Comment: 21 pages, 11 figure
On the path-avoidance vertex-coloring game
For any graph and any integer , the \emph{online vertex-Ramsey
density of and }, denoted , is a parameter defined via a
deterministic two-player Ramsey-type game (Painter vs.\ Builder). This
parameter was introduced in a recent paper \cite{mrs11}, where it was shown
that the online vertex-Ramsey density determines the threshold of a similar
probabilistic one-player game (Painter vs.\ the binomial random graph
). For a large class of graphs , including cliques, cycles,
complete bipartite graphs, hypercubes, wheels, and stars of arbitrary size, a
simple greedy strategy is optimal for Painter and closed formulas for
are known. In this work we show that for the case where
is a (long) path, the picture is very different. It is not hard to see that
for an appropriately defined integer
, and that the greedy strategy gives a lower bound of
. We construct and analyze Painter strategies that
improve on this greedy lower bound by a factor polynomial in , and we
show that no superpolynomial improvement is possible
On-line Ramsey numbers
Consider the following game between two players, Builder and Painter. Builder
draws edges one at a time and Painter colours them, in either red or blue, as
each appears. Builder's aim is to force Painter to draw a monochromatic copy of
a fixed graph G. The minimum number of edges which Builder must draw,
regardless of Painter's strategy, in order to guarantee that this happens is
known as the on-line Ramsey number \tilde{r}(G) of G. Our main result, relating
to the conjecture that \tilde{r}(K_t) = o(\binom{r(t)}{2}), is that there
exists a constant c > 1 such that \tilde{r}(K_t) \leq c^{-t} \binom{r(t)}{2}
for infinitely many values of t. We also prove a more specific upper bound for
this number, showing that there exists a constant c such that \tilde{r}(K_t)
\leq t^{-c \frac{\log t}{\log \log t}} 4^t. Finally, we prove a new upper bound
for the on-line Ramsey number of the complete bipartite graph K_{t,t}.Comment: 11 page
Francis Bacon and the practice of painting
This article addresses the question about why painting continues to be relevant in our contemporary cultural climate. A key reason can be located in the means by which the material of paint can be utilized, manipulated, and perceived through entire sensory and bodily mechanisms. As the practice of Francis Bacon (1909–1992) demonstrates, it is within the elusive behaviour and handling of pigment that the full transformative potential of painting can be released. In fact it can activate a whole field of sensory responses on the part of painter and viewer. The painter can manipulate the material to achieve a variety of effects but needs also to acknowledge how the material can potentially assume an independent life of its own, an almost unruly character. The strength and enduring quality of painting which links modern to postmodern practice, lies in its potential to utilise the painter's tacit skills as well as releasing the inherent and ‘unruly’ qualities of the pigment. The potential of painting practice lies within the orbit of the individual painter who can recognize implicitly how to let the paint ‘work’ according to the needs of the image being constructed
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