28,915 research outputs found
Mixed strategy may outperform pure strategy: An initial study
In pure strategy meta-heuristics, only one search strategy is applied for all
time. In mixed strategy meta-heuristics, each time one search strategy is
chosen from a strategy pool with a probability and then is applied. An example
is classical genetic algorithms, where either a mutation or crossover operator
is chosen with a probability each time. The aim of this paper is to compare the
performance between mixed strategy and pure strategy meta-heuristic algorithms.
First an experimental study is implemented and results demonstrate that mixed
strategy evolutionary algorithms may outperform pure strategy evolutionary
algorithms on the 0-1 knapsack problem in up to 77.8% instances. Then
Complementary Strategy Theorem is rigorously proven for applying mixed strategy
at the population level. The theorem asserts that given two meta-heuristic
algorithms where one uses pure strategy 1 and another uses pure strategy 2, the
condition of pure strategy 2 being complementary to pure strategy 1 is
sufficient and necessary if there exists a mixed strategy meta-heuristics
derived from these two pure strategies and its expected number of generations
to find an optimal solution is no more than that of using pure strategy 1 for
any initial population, and less than that of using pure strategy 1 for some
initial population
Competitive Advantage for Multiple-Memory Strategies in an Artificial Market
We consider a simple binary market model containing competitive agents.
The novel feature of our model is that it incorporates the tendency shown by
traders to look for patterns in past price movements over multiple time scales,
i.e. {\em multiple memory-lengths}. In the regime where these memory-lengths
are all small, the average winnings per agent exceed those obtained for either
(1) a pure population where all agents have equal memory-length, or (2) a mixed
population comprising sub-populations of equal-memory agents with each
sub-population having a different memory-length. Agents who consistently play
strategies of a given memory-length, are found to win more on average --
switching between strategies with different memory lengths incurs an effective
penalty, while switching between strategies of equal memory does not. Agents
employing short-memory strategies can outperform agents using long-memory
strategies, even in the regime where an equal-memory system would have favored
the use of long-memory strategies. Using the many-body `Crowd-Anticrowd'
theory, we obtain analytic expressions which are in good agreement with the
observed numerical results. In the context of financial markets, our results
suggest that multiple-memory agents have a better chance of identifying price
patterns of unknown length and hence will typically have higher winnings.Comment: Talk to be given at the SPIE conference on Econophysics and Finance,
in the International Symposium 'Fluctuations and Noise', 23-26 May 2005 in
Austin, Texa
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
Unsupervised Domain Adaptation using Graph Transduction Games
Unsupervised domain adaptation (UDA) amounts to assigning class labels to the
unlabeled instances of a dataset from a target domain, using labeled instances
of a dataset from a related source domain. In this paper, we propose to cast
this problem in a game-theoretic setting as a non-cooperative game and
introduce a fully automatized iterative algorithm for UDA based on graph
transduction games (GTG). The main advantages of this approach are its
principled foundation, guaranteed termination of the iterative algorithms to a
Nash equilibrium (which corresponds to a consistent labeling condition) and
soft labels quantifying the uncertainty of the label assignment process. We
also investigate the beneficial effect of using pseudo-labels from linear
classifiers to initialize the iterative process. The performance of the
resulting methods is assessed on publicly available object recognition
benchmark datasets involving both shallow and deep features. Results of
experiments demonstrate the suitability of the proposed game-theoretic approach
for solving UDA tasks.Comment: Oral IJCNN 201
Correlation of Positive and Negative Reciprocity Fails to Confer an Evolutionary Advantage: Phase Transitions to Elementary Strategies
Economic experiments reveal that humans value cooperation and fairness. Punishing unfair behavior is therefore common, and according to the theory of strong reciprocity, it is also directly related to rewarding cooperative behavior. However, empirical data fail to confirm that positive and negative reciprocity are correlated. Inspired by this disagreement, we determine whether the combined application of reward and punishment is evolutionarily advantageous. We study a spatial public goods game, where in addition to the three elementary strategies of defection, rewarding, and punishment, a fourth strategy that combines the latter two competes for space. We find rich dynamical behavior that gives rise to intricate phase diagrams where continuous and discontinuous phase transitions occur in succession. Indirect territorial competition, spontaneous emergence of cyclic dominance, as well as divergent fluctuations of oscillations that terminate in an absorbing phase are observed. Yet, despite the high complexity of solutions, the combined strategy can survive only in very narrow and unrealistic parameter regions. Elementary strategies, either in pure or mixed phases, are much more common and likely to prevail. Our results highlight the importance of patterns and structure in human cooperation, which should be considered in future experiments
One-qubit fingerprinting schemes
Fingerprinting is a technique in communication complexity in which two
parties (Alice and Bob) with large data sets send short messages to a third
party (a referee), who attempts to compute some function of the larger data
sets. For the equality function, the referee attempts to determine whether
Alice's data and Bob's data are the same. In this paper, we consider the
extreme scenario of performing fingerprinting where Alice and Bob both send
either one bit (classically) or one qubit (in the quantum regime) messages to
the referee for the equality problem. Restrictive bounds are demonstrated for
the error probability of one-bit fingerprinting schemes, and show that it is
easy to construct one-qubit fingerprinting schemes which can outperform any
one-bit fingerprinting scheme. The author hopes that this analysis will provide
results useful for performing physical experiments, which may help to advance
implementations for more general quantum communication protocols.Comment: 9 pages; Fixed some typos; changed order of bibliographical
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