2,146 research outputs found
Evolutionary games on graphs
Game theory is one of the key paradigms behind many scientific disciplines
from biology to behavioral sciences to economics. In its evolutionary form and
especially when the interacting agents are linked in a specific social network
the underlying solution concepts and methods are very similar to those applied
in non-equilibrium statistical physics. This review gives a tutorial-type
overview of the field for physicists. The first three sections introduce the
necessary background in classical and evolutionary game theory from the basic
definitions to the most important results. The fourth section surveys the
topological complications implied by non-mean-field-type social network
structures in general. The last three sections discuss in detail the dynamic
behavior of three prominent classes of models: the Prisoner's Dilemma, the
Rock-Scissors-Paper game, and Competing Associations. The major theme of the
review is in what sense and how the graph structure of interactions can modify
and enrich the picture of long term behavioral patterns emerging in
evolutionary games.Comment: Review, final version, 133 pages, 65 figure
An entanglement-based protocol for simultaneous reciprocal information exchange between 2 players
Let us consider a situation where two information brokers, whose currency is,
of course, information, need to reciprocally exchange information. The two
brokers, being somewhat distrustful, would like a third, mutually trusted,
entity to be involved in the exchange process so as to guarantee the successful
completion of the transaction, and also verify that it indeed took place. Can
this be done in such a way that both brokers receive their information
simultaneously and securely, and without the trusted intermediary ending up
knowing the exchanged information? This work presents and rigorously analyzes a
new quantum entanglement-based protocol that provides a solution to the above
problem. The proposed protocol is aptly named entanglement-based reciprocal
simultaneous information exchange protocol. Its security is ultimately based on
the assumption of the existence of a third trusted party. Although, the
reciprocal information flow is between our two information brokers, the third
entity plays a crucial role in mediating this process, being a guarantor and a
verifier. The phenomenon of quantum entanglement is the cornerstone of this
protocol, as it makes possible its implementation even when all entities are
spatially separated, and ensuring that, upon completion, the trusted third
party remains oblivious of the actual information that was exchanged
The Physics of Open Ended Evolution
abstract: What makes living systems different than non-living ones? Unfortunately this question is impossible to answer, at least currently. Instead, we must face computationally tangible questions based on our current understanding of physics, computation, information, and biology. Yet we have few insights into how living systems might quantifiably differ from their non-living counterparts, as in a mathematical foundation to explain away our observations of biological evolution, emergence, innovation, and organization. The development of a theory of living systems, if at all possible, demands a mathematical understanding of how data generated by complex biological systems changes over time. In addition, this theory ought to be broad enough as to not be constrained to an Earth-based biochemistry. In this dissertation, the philosophy of studying living systems from the perspective of traditional physics is first explored as a motivating discussion for subsequent research. Traditionally, we have often thought of the physical world from a bottom-up approach: things happening on a smaller scale aggregate into things happening on a larger scale. In addition, the laws of physics are generally considered static over time. Research suggests that biological evolution may follow dynamic laws that (at least in part) change as a function of the state of the system. Of the three featured research projects, cellular automata (CA) are used as a model to study certain aspects of living systems in two of them. These aspects include self-reference, open-ended evolution, local physical universality, subjectivity, and information processing. Open-ended evolution and local physical universality are attributed to the vast amount of innovation observed throughout biological evolution. Biological systems may distinguish themselves in terms of information processing and storage, not outside the theory of computation. The final research project concretely explores real-world phenomenon by means of mapping dominance hierarchies in the evolution of video game strategies. Though the main question of how life differs from non-life remains unanswered, the mechanisms behind open-ended evolution and physical universality are revealed.Dissertation/ThesisDoctoral Dissertation Physics 201
A 2 & 3 Player Scheme for Quantum Direct Communication
This paper introduces two information-theoretically secure protocols that
achieve quantum secure direct communication between Alice and Bob in the first
case, and among Alice, Bod and Charlie in the second case. Both protocols use
the same novel method to embed the secret information in the entangled
composite system of the players. The way of encoding the information is the
main novelty of this paper and the distinguishing feature compared to previous
works in the field. The advantage of this method is that it is easily
extensible and can be generalized to a setting involving three, or even more,
players, as demonstrated with the second protocol. This trait can be beneficial
when two spatially separated players posses only part of the secret information
that must be combined and transmitted to Alice in order for her to reveal the
complete secret. Using the three player protocol, this task can be achieved in
one go, without the need to apply a typical QSDC protocol twice, where Alice
first receives Bob's information and afterwards Charlie's information. Another
characteristic of both protocols is their simplicity and uniformity. The two
player protocol relies on EPR pairs, and the three player protocol on GHZ
triples, which can be easily prepared with our current technology. In the same
vein, the local quantum circuits are similar or identical, and are easily
constructible as they employ only Hadamard and CNOT gates
Game Theory Relaunched
The game is on. Do you know how to play? Game theory sets out to explore what can be said about making decisions which go beyond accepting the rules of a game. Since 1942, a well elaborated mathematical apparatus has been developed to do so; but there is more. During the last three decades game theoretic reasoning has popped up in many other fields as well - from engineering to biology and psychology. New simulation tools and network analysis have made game theory omnipresent these days. This book collects recent research papers in game theory, which come from diverse scientific communities all across the world; they combine many different fields like economics, politics, history, engineering, mathematics, physics, and psychology. All of them have as a common denominator some method of game theory. Enjoy
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