4,509 research outputs found
Visibility Graphs, Dismantlability, and the Cops and Robbers Game
We study versions of cop and robber pursuit-evasion games on the visibility
graphs of polygons, and inside polygons with straight and curved sides. Each
player has full information about the other player's location, players take
turns, and the robber is captured when the cop arrives at the same point as the
robber. In visibility graphs we show the cop can always win because visibility
graphs are dismantlable, which is interesting as one of the few results
relating visibility graphs to other known graph classes. We extend this to show
that the cop wins games in which players move along straight line segments
inside any polygon and, more generally, inside any simply connected planar
region with a reasonable boundary. Essentially, our problem is a type of
pursuit-evasion using the link metric rather than the Euclidean metric, and our
result provides an interesting class of infinite cop-win graphs.Comment: 23 page
Revolutionaries and spies on random graphs
Pursuit-evasion games, such as the game of Revolutionaries and Spies, are a
simplified model for network security. In the game we consider in this paper, a
team of revolutionaries tries to hold an unguarded meeting consisting of
revolutionaries. A team of spies wants to prevent this forever. For
given and , the minimum number of spies required to win on a graph
is the spy number . We present asymptotic results for the game
played on random graphs for a large range of , and
. The behaviour of the spy number is analyzed completely for dense
graphs (that is, graphs with average degree at least n^{1/2+\eps} for some
\eps > 0). For sparser graphs, some bounds are provided
Visibility graphs, dismantlability, and the cops and robbers game
We study versions of cop and robber pursuit–evasion games on the visibility graphs of polygons, and inside polygons with straight and curved sides. Each player has full information about the other player's location, players take turns, and the robber is captured when the cop arrives at the same point as the robber. In visibility graphs we show the cop can always win because visibility graphs are , which is interesting as one of the few results relating visibility graphs to other known graph classes. We extend this to show that the cop wins games in which players move along straight line segments inside any polygon and, more generally, inside any simply connected planar region with a reasonable boundary. Essentially, our problem is a type of pursuit–evasion using the link metric rather than the Euclidean metric, and our result provides an interesting class of infinite cop-win graphs
Path Planning Problems with Side Observations-When Colonels Play Hide-and-Seek
Resource allocation games such as the famous Colonel Blotto (CB) and
Hide-and-Seek (HS) games are often used to model a large variety of practical
problems, but only in their one-shot versions. Indeed, due to their extremely
large strategy space, it remains an open question how one can efficiently learn
in these games. In this work, we show that the online CB and HS games can be
cast as path planning problems with side-observations (SOPPP): at each stage, a
learner chooses a path on a directed acyclic graph and suffers the sum of
losses that are adversarially assigned to the corresponding edges; and she then
receives semi-bandit feedback with side-observations (i.e., she observes the
losses on the chosen edges plus some others). We propose a novel algorithm,
EXP3-OE, the first-of-its-kind with guaranteed efficient running time for SOPPP
without requiring any auxiliary oracle. We provide an expected-regret bound of
EXP3-OE in SOPPP matching the order of the best benchmark in the literature.
Moreover, we introduce additional assumptions on the observability model under
which we can further improve the regret bounds of EXP3-OE. We illustrate the
benefit of using EXP3-OE in SOPPP by applying it to the online CB and HS games.Comment: Previously, this work appeared as arXiv:1911.09023 which was
mistakenly submitted as a new article (has been submitted to be withdrawn).
This is a preprint of the work published in Proceedings of the 34th AAAI
Conference on Artificial Intelligence (AAAI
Two-Dimensional Pursuit-Evasion in a Compact Domain with Piecewise Analytic Boundary
In a pursuit-evasion game, a team of pursuers attempt to capture an evader.
The players alternate turns, move with equal speed, and have full information
about the state of the game. We consider the most restictive capture condition:
a pursuer must become colocated with the evader to win the game. We prove two
general results about pursuit-evasion games in topological spaces. First, we
show that one pursuer has a winning strategy in any CAT(0) space under this
restrictive capture criterion. This complements a result of Alexander, Bishop
and Ghrist, who provide a winning strategy for a game with positive capture
radius. Second, we consider the game played in a compact domain in Euclidean
two-space with piecewise analytic boundary and arbitrary Euler characteristic.
We show that three pursuers always have a winning strategy by extending recent
work of Bhadauria, Klein, Isler and Suri from polygonal environments to our
more general setting.Comment: 21 pages, 6 figure
- …