40
40

Sep 18, 2013
09/13

by
Andrea Rapisarda; Alessandro Pluchino

texts

######
eye 40

######
favorite 0

######
comment 0

In the comment by T.Dauxois et al.,(cond-mat/0605445), the authors question our application of the nonextensive statistical mechanics proposed by Tsallis, to explain the anomalous dynamics of the Hamiltonian Mean Field (HMF) model. More specifically they claim that the explanation of the metastability found in the out-of-equilibrium dynamics is only a fitting procedure and is also in contrast with a previous application. This criticism mostly relies on recent studies based on the Vlasov...

Source: http://arxiv.org/abs/cond-mat/0605502v1

29
29

Sep 18, 2013
09/13

by
Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 29

######
favorite 0

######
comment 0

We review the anomalies of the HMF model and discuss the robusteness of the glassy features vs the initial conditions. Connections to Tsallis statistics are also addressed.

Source: http://arxiv.org/abs/cond-mat/0509031v2

82
82

Sep 23, 2013
09/13

by
Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 82

######
favorite 0

######
comment 0

We briefly discuss the state of the art on the anomalous dynamics of the Hamiltonian Mean Field model. We stress the important role of the initial conditions for understanding the microscopic nature of the intriguing metastable quasi stationary states observed in the model and the connections to Tsallis statistics and glassy dynamics. We also present new results on the existence of metastable states in the Kuramoto model and discuss the similarities with those found in the HMF model. The...

Source: http://arxiv.org/abs/cond-mat/0511570v1

1
1.0

Jun 29, 2018
06/18

by
Alessio Emanuele Biondo; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 1

######
favorite 0

######
comment 0

We present a simple order book mechanism that regulates an artificial financial market with self-organized criticality dynamics and fat tails of returns distribution. The model shows the role played by individual imitation in determining trading decisions, while fruitfully replicates typical aggregate market behavior as the "self-fulfilling prophecy". We also address the role of random traders as a possible decentralized solution to dampen market fluctuations.

Topics: Trading and Market Microstructure, Quantitative Finance, Physics, Physics and Society

Source: http://arxiv.org/abs/1602.08270

37
37

Sep 23, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 37

######
favorite 0

######
comment 0

We discuss two models of opinion dynamics. First wepresent a brief review of the Hegselmann and Krause (HK) compromise model in two dimensions, showing that it is possible to simulate the dynamics in the limit of an infinite number of agents by solving numerically a rate equation for a continuum distribution of opinions. Then, we discuss the Opinion Changing Rate (OCR) model, which allows to study under which conditions a group of agents with a different natural tendency (rate) to change...

Source: http://arxiv.org/abs/physics/0510141v5

1
1.0

Jun 30, 2018
06/18

by
Alessio Emanuele Biondo; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 1

######
favorite 0

######
comment 0

In this paper, making use of recent statistical physics techniques and models, we address the specific role of randomness in financial markets, both at the micro and the macro level. In particular, we review some recent results obtained about the effectiveness of random strategies of investment, compared with some of the most used trading strategies for forecasting the behavior of real financial indexes. We also push forward our analysis by means of a Self-Organized Criticality model, able to...

Topics: Physics, Quantitative Finance, Physics and Society, General Finance

Source: http://arxiv.org/abs/1405.5805

0
0.0

Jun 30, 2018
06/18

by
Dario A. ZappalÃ ; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 0

######
favorite 0

######
comment 0

We study the emergence of altruistic behaviour in collective games. In particular, we take into account Toral's version of collective Parrondo's paradoxical games, in which the redistribution of capital between agents, who can play different strategies, creates a positive trend of increasing capital. In this framework, we insert two categories of players, altruistic and selfish ones, and see how they interact and how their capital evolves. More in detail, we analyse the positive effects of...

Topics: Physics, Physics and Society

Source: http://arxiv.org/abs/1401.3946

90
90

Sep 18, 2013
09/13

by
Alessandro Pluchino; Andrea Rapisarda; Cesare Garofalo

texts

######
eye 90

######
favorite 0

######
comment 0

The Peter principle has been recently investigated by means of an agent-based simulation and its validity has been numerically corroborated. It has been confirmed that, within certain conditions, it can really influence in a negative way the efficiency of a pyramidal organization adopting meritocratic promotions. It was also found that, in order to bypass these effects, alternative promotion strategies should be adopted, as for example a random selection choice. In this paper, within the same...

Source: http://arxiv.org/abs/1102.2837v2

29
29

Sep 18, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 29

######
favorite 0

######
comment 0

We study the relaxation dynamics of a Hamiltonian system of N fully-coupled XY spins. The thermodynamics of the system predicts a ferromagnetic and a paramagnetic phase. Starting from out-of-equilibrium initial conditions, the dynamics at constant energy drives the system into quasi-stationary states (QSS) characterized by dynamical frustration. We introduce the spin polarization as a new order parameter which allows to interpret the dynamically generated QSS regime as a glassy phase of the...

Source: http://arxiv.org/abs/cond-mat/0306374v4

110
110

Sep 18, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 110

######
favorite 0

######
comment 0

We discuss the role of the initial conditions for the dynamical anomalies observed in the quasi-stationary states of the Hamiltonian Mean Field (HMF) model.

Source: http://arxiv.org/abs/cond-mat/0401582v1

39
39

Sep 20, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 39

######
favorite 0

######
comment 0

The dynamics and the thermodynamics of particles/spins interacting via long-range forces display several unusual features with respect to systems with short-range interactions. The Hamiltonian Mean Field (HMF) model, a Hamiltonian system of N classical inertial spins with infinite-range interactions represents a paradigmatic example of this class of systems. The equilibrium properties of the model can be derived analytically in the canonical ensemble: in particular the model shows a second...

Source: http://arxiv.org/abs/cond-mat/0410213v1

42
42

Sep 23, 2013
09/13

by
Giovanna Miritello; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 42

######
favorite 0

######
comment 0

We study the relationship between chaotic behavior and the Central Limit Theorem (CLT) in the Kuramoto model. We calculate sums of angles at equidistant times along deterministic trajectories of single oscillators and we show that, when chaos is sufficiently strong, the Pdfs of the sums tend to a Gaussian, consistently with the standard CLT. On the other hand, when the system is at the "edge of chaos" (i.e. in a regime with vanishing Lyapunov exponents), robust $q$-Gaussian-like...

Source: http://arxiv.org/abs/0903.4400v2

3
3.0

Jun 29, 2018
06/18

by
Alessio Emanuele Biondo; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 3

######
favorite 0

######
comment 0

We introduce a new Self-Organized Criticality (SOC) model for simulating price evolution in an artificial financial market, based on a multilayer network of traders. The model also implements, in a quite realistic way with respect to previous studies, the order book dy- namics, by considering two assets with variable fundamental prices. Fat tails in the probability distributions of normalized returns are observed, together with other features of real financial markets.

Topics: Trading and Market Microstructure, Quantitative Finance, Physics, Physics and Society

Source: http://arxiv.org/abs/1606.09194

78
78

Sep 22, 2013
09/13

by
Alessandro Pluchino; Giuseppe Andronico; Andrea Rapisarda

texts

######
eye 78

######
favorite 0

######
comment 0

We present a Monte Carlo numerical investigation of the Hamiltonian Mean Field (HMF) model. We begin by discussing canonical Metropolis Monte Carlo calculations, in order to check the caloric curve of the HMF model and study finite size effects. In the second part of the paper, we present numerical simulations obtained by means of a modified Monte Carlo procedure with the aim to test the stability of those states at minimum temperature and zero magnetization (homogeneous Quasi Stationary...

Source: http://arxiv.org/abs/cond-mat/0409768v1

28
28

Sep 20, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 28

######
favorite 0

######
comment 0

We discuss an effective spin-glass Hamiltonian which can be used to study the glassy-like dynamics observed in the metastable states of the Hamiltonian Mean Field (HMF) model. By means of the Replica formalism, we were able to find a self-consistent equation for the glassy order parameter which reproduces, in a restricted energy region below the phase transition, the microcanonical simulations for the polarization order parameter recently introducted in the HMF model.

Source: http://arxiv.org/abs/cond-mat/0506665v4

33
33

Sep 23, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 33

######
favorite 0

######
comment 0

We discuss the glassy dynamics recently found in the meta-equilibrium quasi stationary states (QSS) of the HMF model. The relevance of the initial conditions and the connection with Tsallis nonextensive thermostatistics is also addressed.

Source: http://arxiv.org/abs/cond-mat/0312425v1

25
25

Sep 18, 2013
09/13

by
Alessandro Pluchino; Andrea Rapisarda; Vito Latora

texts

######
eye 25

######
favorite 0

######
comment 0

We have recently introduced an efficient method for the detection and identification of modules in complex networks, based on the de-synchronization properties (dynamical clustering) of phase oscillators. In this paper we apply the dynamical clustering tecnique to the identification of communities of marine organisms living in the Chesapeake Bay food web. We show that our algorithm is able to perform a very reliable classification of the real communities existing in this ecosystem by using...

Source: http://arxiv.org/abs/0806.4276v2

29
29

Sep 19, 2013
09/13

by
Alessandro Pluchino; Vito Latora; Andrea Rapisarda

texts

######
eye 29

######
favorite 0

######
comment 0

We study the microscopic dynamics of the metastable Quasi-Stationary States (QSS) in the Hamiltonian Mean Field (HMF) model, a Hamiltonian system of N classical inertial spins with infinite-range interactions which shows a second order phase transition. In order to understand the origin of metastability, which appears in an energy region below the critical point, we consider two different classes of out-of-equilibrium initial conditions, both leading to QSS, and having respectively initial...

Source: http://arxiv.org/abs/cond-mat/0303081v3

27
27

Sep 18, 2013
09/13

by
Alessio Emanuele Biondo; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 27

######
favorite 0

######
comment 0

In this paper we focus on the beneficial role of random strategies in social sciences by means of simple mathematical and computational models. We briefly review recent results obtained by two of us in previous contributions for the case of the Peter principle and the efficiency of a Parliament. Then, we develop a new application of random strategies to the case of financial trading and discuss in detail our findings about forecasts of markets dynamics.

Source: http://arxiv.org/abs/1209.5881v2

36
36

Sep 18, 2013
09/13

by
Filippo Caruso; Alessandro Pluchino; Vito Latora; Sergio Vinciguerra; Andrea Rapisarda

texts

######
eye 36

######
favorite 0

######
comment 0

We perform a new analysis on the dissipative Olami-Feder-Christensen model on a small world topology considering avalanche size differences. We show that when criticality appears the Probability Density Functions (PDFs) for the avalanche size differences at different times have fat tails with a q-Gaussian shape. This behaviour does not depend on the time interval adopted and is found also when considering energy differences between real earthquakes. Such a result can be analytically understood...

Source: http://arxiv.org/abs/cond-mat/0606118v4

86
86

Jul 20, 2013
07/13

by
Constantino Tsallis; Andrea Rapisarda; Alessandro Pluchino; Ernesto P. Borges

texts

######
eye 86

######
favorite 0

######
comment 0

We discuss the non-Boltzmannian nature of quasi-stationary states in the Hamiltonian Mean Field (HMF) model, a paradigmatic model for long-range interacting classical many-body systems. We present a theorem excluding the Boltzmann-Gibbs exponential weight in Gibbs $\Gamma$-space of microscopic configurations, and comment a paper recently published by Baldovin and Orlandini (2006). On the basis of the points here discussed, the ongoing debate on the possible application, within appropriate...

Source: http://arxiv.org/abs/cond-mat/0609399v3

34
34

Sep 18, 2013
09/13

by
Santo Fortunato; Vito Latora; Alessandro Pluchino; Andrea Rapisarda

texts

######
eye 34

######
favorite 0

######
comment 0

We study the continuum opinion dynamics of the compromise model of Krause and Hegselmann for a community of mutually interacting agents, by solving numerically a rate equation. The opinions are here represented by bidimensional vectors with real-valued components. We study the situation starting from a uniform probability distribution for the opinion configuration and for different shapes of the confidence range. In all cases, we find that the thresholds for consensus and cluster merging either...

Source: http://arxiv.org/abs/physics/0504017v1

40
40

Sep 18, 2013
09/13

by
Filippo Caruso; Vito Latora; Alessandro Pluchino; Andrea Rapisarda; Bosiljka Tadic

texts

######
eye 40

######
favorite 0

######
comment 0

We investigate numerically the Self Organized Criticality (SOC) properties of the dissipative Olami-Feder-Christensen model on small-world and scale-free networks. We find that the small-world OFC model exhibits self-organized criticality. Indeed, in this case we observe power law behavior of earthquakes size distribution with finite size scaling for the cut-off region. In the scale-free OFC model, instead, the strength of disorder hinders synchronization and does not allow to reach a critical...

Source: http://arxiv.org/abs/cond-mat/0509808v2

23
23

Sep 20, 2013
09/13

by
Alessandro Pluchino; Stefano Boccaletti; Vito Latora; Andrea Rapisarda

texts

######
eye 23

######
favorite 0

######
comment 0

In this paper we discuss opinion dynamics in the Opinion Changing Rate (OCR) model, recently proposed (A.Pluchino, V.Latora and A.Rapisarda Int. J. Mod. Phys. C, 16, No.4, 515-531 (2005)). The OCR model allows to study whether and how a group of social agents, with a different intrinsic tendency rate to change opinion, finds agreement. In particular, we implement the OCR model on a small graph describing the topology of a real social system. The nodes of the graph are scientists partecipating...

Source: http://arxiv.org/abs/physics/0607210v1