75,297 research outputs found
The Competition Numbers of Johnson Graphs with Diameter Four
In 2010, Kim, Park and Sano studied the competition numbers of Johnson graphs. They gave the competition numbers of J(n,2) and J(n,3).In this note, we consider the competition number of J(n,4)
The competition numbers of ternary Hamming graphs
It is known to be a hard problem to compute the competition number k(G) of a
graph G in general. Park and Sano [13] gave the exact values of the competition
numbers of Hamming graphs H(n,q) if or . In
this paper, we give an explicit formula of the competition numbers of ternary
Hamming graphs.Comment: 6 pages, 2 figure
The competition numbers of Hamming graphs with diameter at most three
The competition graph of a digraph D is a graph which has the same vertex set
as D and has an edge between x and y if and only if there exists a vertex v in
D such that (x,v) and (y,v) are arcs of D. For any graph G, G together with
sufficiently many isolated vertices is the competition graph of some acyclic
digraph. The competition number k(G) of a graph G is defined to be the smallest
number of such isolated vertices. In general, it is hard to compute the
competition number k(G) for a graph G and it has been one of important research
problems in the study of competition graphs. In this paper, we compute the
competition numbers of Hamming graphs with diameter at most three.Comment: 12 pages, 1 figur
Understanding recurrent crime as system-immanent collective behavior
Containing the spreading of crime is a major challenge for society. Yet,
since thousands of years, no effective strategy has been found to overcome
crime. To the contrary, empirical evidence shows that crime is recurrent, a
fact that is not captured well by rational choice theories of crime. According
to these, strong enough punishment should prevent crime from happening. To gain
a better understanding of the relationship between crime and punishment, we
consider that the latter requires prior discovery of illicit behavior and study
a spatial version of the inspection game. Simulations reveal the spontaneous
emergence of cyclic dominance between ''criminals'', ''inspectors'', and
''ordinary people'' as a consequence of spatial interactions. Such cycles
dominate the evolutionary process, in particular when the temptation to commit
crime or the cost of inspection are low or moderate. Yet, there are also
critical parameter values beyond which cycles cease to exist and the population
is dominated either by a stable mixture of criminals and inspectors or one of
these two strategies alone. Both continuous and discontinuous phase transitions
to different final states are possible, indicating that successful strategies
to contain crime can be very much counter-intuitive and complex. Our results
demonstrate that spatial interactions are crucial for the evolutionary outcome
of the inspection game, and they also reveal why criminal behavior is likely to
be recurrent rather than evolving towards an equilibrium with monotonous
parameter dependencies.Comment: 9 two-column pages, 5 figures; accepted for publication in PLoS ON
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