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Papers by Andrea Rapisarda

Advances in Complex Systems

While wealth distribution in the world is highly skewed and heavy-tailed, human talent — as the m... more While wealth distribution in the world is highly skewed and heavy-tailed, human talent — as the majority of individual features — is normally distributed. In a recent computational study by Pluchino et al. [Talent vs luck: The role of randomness in success and failure, Adv. Complex Syst. 21(03–04) (2018) 1850014], it has been shown that the combined effects of both random external factors (lucky and unlucky events) and multiplicative dynamics in capital accumulation are able to clarify this apparent contradiction. We introduce here a simplified version (STvL) of the original Talent versus Luck (TvL) model, where only lucky events are present, and verify that its dynamical rules lead to the same very large wealth inequality. We also derive some analytical approximations aimed to capture the mechanism responsible for the creation of such wealth inequality from a Gaussian-distributed talent. Under these approximations, our analysis is able to reproduce quite well the results of the num...

The European Physical Journal Special Topics

Entropy

An entropic functional S is said additive if it satisfies, for any two probabilistically independ... more An entropic functional S is said additive if it satisfies, for any two probabilistically independent systems A and B, that S ( A + B ) = S ( A ) + S ( B ) [...]

Advances in Complex Systems

The largely dominant meritocratic paradigm of highly competitive Western cultures is rooted on th... more The largely dominant meritocratic paradigm of highly competitive Western cultures is rooted on the belief that success is mainly due, if not exclusively, to personal qualities such as talent, intelligence, skills, smartness, efforts, willfulness, hard work or risk taking. Sometimes, we are willing to admit that a certain degree of luck could also play a role in achieving significant success. But, as a matter of fact, it is rather common to underestimate the importance of external forces in individual successful stories. It is very well known that intelligence (or, more in general, talent and personal qualities) exhibits a Gaussian distribution among the population, whereas the distribution of wealth — often considered as a proxy of success — follows typically a power law (Pareto law), with a large majority of poor people and a very small number of billionaires. Such a discrepancy between a Normal distribution of inputs, with a typical scale (the average talent or intelligence), and ...

The European Physical Journal Special Topics

We study the emergence of altruistic behaviour in collective games. In particular, we take into a... more 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 altruistic behaviour, but we also point out how selfish players take advantage of that situation. The general result is that altruistic behaviour is discouraged, because selfish players get richer while altruistic ones get poorer. We also consider a smarter way of being altruistic, based on reputation, called "selective altruism", which prevents selfish players from taking advantage of altruistic ones. In this new situation it is altruism, and not selfishness, to be encouraged and stabilized. Finally, we introduce a mechanism of imitation between players and study how it influences the composition of the population of both altruistic and selfish players as a function of time for different initial conditions and network topologies adopted.

Eprint Arxiv Nucl Th 9212009, Dec 16, 1992

In a recent letter (PRL 95, 190601 (2005)), T.M. Rocha Filho and coworkers address the very inter... more In a recent letter (PRL 95, 190601 (2005)), T.M. Rocha Filho and coworkers address the very interesting issue of the entropic form to be used for Hamiltonians with long-range interactions. In our opinion the letter misses several points quite debated in the recent literature which are of fundamental importance for a complete discussion of this problem. Moreover it contains several statements which are not true or not corroborated by any evidence. In this comment we discuss these arguments and severely question the generality of the conclusions of this letter.

AIP Conference Proceedings, 2007

ABSTRACT Based on the method developed in [T.D. Frank, Physica A 310 397-412 (2002)], we have der... more ABSTRACT Based on the method developed in [T.D. Frank, Physica A 310 397-412 (2002)], we have derived a non-linear Fokker-Planck equation for non-equilibrium systems related to the kappa-entropy. This kinetic equation can be characterized by the associated Lyapunov functional or Bregman type divergence, which is related to the difference of the kappa-generalized free-energies.

Interdisciplinary Aspects of Turbulence, Aug 1, 2005

AIP Conference Proceedings, 2007

AIP Conference Proceedings, 2007

Abstract There are various classes of models, in which individuals are assumed to make their bina... more Abstract There are various classes of models, in which individuals are assumed to make their binary choices dependent upon gains and losses, including social ones, which they evaluate for themselves. At each discrete time step t every individual has to make a binary decision: sigma it=+ 1 or sigma it=-1: sigma i t+ 1= f (sigma it,{sigma jt}). In different approaches, deterministic part is distinguished from a random (non-rational) part.

AIP Conference Proceedings, 2007

ABSTRACT Shannon additivity, one of the Shannon‐Khinchin axioms, determines a lower bound of aver... more ABSTRACT Shannon additivity, one of the Shannon‐Khinchin axioms, determines a lower bound of average code length of a D‐ary code tree. As its generalization, the generalized Shannon additivity is applied to determining a lower bound of average description length of a rooted tree which we call “q‐generalized D‐ary code tree”. The generalized Shannon additivity is one of the generalized Shannon‐Khinchin axioms for Tsallis entropy. This reveals that Tsallis entropy is a lower bound of average description length for the q‐generalized D‐ary code tree.

AIP Conference Proceedings, 2007

Advances in Complex Systems

While wealth distribution in the world is highly skewed and heavy-tailed, human talent — as the m... more While wealth distribution in the world is highly skewed and heavy-tailed, human talent — as the majority of individual features — is normally distributed. In a recent computational study by Pluchino et al. [Talent vs luck: The role of randomness in success and failure, Adv. Complex Syst. 21(03–04) (2018) 1850014], it has been shown that the combined effects of both random external factors (lucky and unlucky events) and multiplicative dynamics in capital accumulation are able to clarify this apparent contradiction. We introduce here a simplified version (STvL) of the original Talent versus Luck (TvL) model, where only lucky events are present, and verify that its dynamical rules lead to the same very large wealth inequality. We also derive some analytical approximations aimed to capture the mechanism responsible for the creation of such wealth inequality from a Gaussian-distributed talent. Under these approximations, our analysis is able to reproduce quite well the results of the num...

The European Physical Journal Special Topics

Entropy

An entropic functional S is said additive if it satisfies, for any two probabilistically independ... more An entropic functional S is said additive if it satisfies, for any two probabilistically independent systems A and B, that S ( A + B ) = S ( A ) + S ( B ) [...]

Advances in Complex Systems

The largely dominant meritocratic paradigm of highly competitive Western cultures is rooted on th... more The largely dominant meritocratic paradigm of highly competitive Western cultures is rooted on the belief that success is mainly due, if not exclusively, to personal qualities such as talent, intelligence, skills, smartness, efforts, willfulness, hard work or risk taking. Sometimes, we are willing to admit that a certain degree of luck could also play a role in achieving significant success. But, as a matter of fact, it is rather common to underestimate the importance of external forces in individual successful stories. It is very well known that intelligence (or, more in general, talent and personal qualities) exhibits a Gaussian distribution among the population, whereas the distribution of wealth — often considered as a proxy of success — follows typically a power law (Pareto law), with a large majority of poor people and a very small number of billionaires. Such a discrepancy between a Normal distribution of inputs, with a typical scale (the average talent or intelligence), and ...

The European Physical Journal Special Topics

We study the emergence of altruistic behaviour in collective games. In particular, we take into a... more 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 altruistic behaviour, but we also point out how selfish players take advantage of that situation. The general result is that altruistic behaviour is discouraged, because selfish players get richer while altruistic ones get poorer. We also consider a smarter way of being altruistic, based on reputation, called "selective altruism", which prevents selfish players from taking advantage of altruistic ones. In this new situation it is altruism, and not selfishness, to be encouraged and stabilized. Finally, we introduce a mechanism of imitation between players and study how it influences the composition of the population of both altruistic and selfish players as a function of time for different initial conditions and network topologies adopted.

Eprint Arxiv Nucl Th 9212009, Dec 16, 1992

In a recent letter (PRL 95, 190601 (2005)), T.M. Rocha Filho and coworkers address the very inter... more In a recent letter (PRL 95, 190601 (2005)), T.M. Rocha Filho and coworkers address the very interesting issue of the entropic form to be used for Hamiltonians with long-range interactions. In our opinion the letter misses several points quite debated in the recent literature which are of fundamental importance for a complete discussion of this problem. Moreover it contains several statements which are not true or not corroborated by any evidence. In this comment we discuss these arguments and severely question the generality of the conclusions of this letter.

AIP Conference Proceedings, 2007

ABSTRACT Based on the method developed in [T.D. Frank, Physica A 310 397-412 (2002)], we have der... more ABSTRACT Based on the method developed in [T.D. Frank, Physica A 310 397-412 (2002)], we have derived a non-linear Fokker-Planck equation for non-equilibrium systems related to the kappa-entropy. This kinetic equation can be characterized by the associated Lyapunov functional or Bregman type divergence, which is related to the difference of the kappa-generalized free-energies.

Interdisciplinary Aspects of Turbulence, Aug 1, 2005

AIP Conference Proceedings, 2007

AIP Conference Proceedings, 2007

Abstract There are various classes of models, in which individuals are assumed to make their bina... more Abstract There are various classes of models, in which individuals are assumed to make their binary choices dependent upon gains and losses, including social ones, which they evaluate for themselves. At each discrete time step t every individual has to make a binary decision: sigma it=+ 1 or sigma it=-1: sigma i t+ 1= f (sigma it,{sigma jt}). In different approaches, deterministic part is distinguished from a random (non-rational) part.

AIP Conference Proceedings, 2007

ABSTRACT Shannon additivity, one of the Shannon‐Khinchin axioms, determines a lower bound of aver... more ABSTRACT Shannon additivity, one of the Shannon‐Khinchin axioms, determines a lower bound of average code length of a D‐ary code tree. As its generalization, the generalized Shannon additivity is applied to determining a lower bound of average description length of a rooted tree which we call “q‐generalized D‐ary code tree”. The generalized Shannon additivity is one of the generalized Shannon‐Khinchin axioms for Tsallis entropy. This reveals that Tsallis entropy is a lower bound of average description length for the q‐generalized D‐ary code tree.

AIP Conference Proceedings, 2007