On the coevolution of social norms in primitive societies

Two parties bargaining over a pie, the size of which is determined by their previous investment decisions. The bargaining rule is sensitive to investment behavior. Two games are considered. In both, bargaining proceeds according to the Nash Demand Game when a symmetric investments profile is observed. When, on the other hand, an asymmetric investments profile is observed, we assume that bargaining proceeds according to the Ultimatum Game in one case and according to a Dictator Game in the other. We hereby show that in both games when a unique stochastically stable outcome exists it supports an homogeneous behavior in the whole population both at the investment stage and at the distribution stage. A norm of investment and a norm of division must therefore coevolve in the two games, supporting both the efficient investment profile and the egalitarian distribution of the surplus, respectively. The two games differ depending on the conditions needed for the two norms to coevolve. The games are proposed to explain the social norms used in modern hunter-gatherer societies

The emergence of norms of cooperation in stag hunt games with production

In this paper we study a two agents asymmetric stag hunt game. The model has an infinity of strict, Pareto rankable Nash equilibria. The equilibrium selection problem is solved by appealing to the stochastic stability concept put forward by Young (1993). We prove two main results. When the action sets are numerable in.nite sets, then for any value of the distributive parameter we can expect the emergence of a norm involving less than maximal cooperation. When instead the action sets are finite sets of a particular type (in the sense that each agent can choose his maximum optimal effort and fractions of this), then for some value of the distributive parameter we can expect the emergence of a norm involving maximal cooperation

On the co-evolution of investment and bargaining norms

Two parties bargaining over a pie, the size of which is determined by their previous investment decisions. The bargaining rule is sensitive to investment behavior. Two games are considered. In both, bargaining proceeds according to the Nash Demand Game when a symmetric investments profile is observed. When, on the other hand, an asymmetric investments profile is observed, we assume that bargaining proceeds according to the Ultimatum Game in one case and according to a Dictator Game in the other. We hereby show that in both games when a unique stochastically stable outcome exists it supports an homogeneous behavior in the whole population both at the investment stage and at the distribution stage. A norm of investment and a norm of division must therefore coevolve in the two games, supporting both the efficient investment profile and the egalitarian distribution of the surplus, respectively. The two games differ depending on the conditions needed for the two norms to coevolve. The games are proposed to explain the social norms used in modern hunter-gatherer societies

A remark on the experimental evidence from tacit coordination games

This paper proposes an interpretation of the experimental evidence on tacit coordination games involving randomly matched players provided by Van Huyck, Battalio and Beil (1990), based on the notion of stochastic stability. When the model is calibrated with the parameters chosen in the experiment, it predicts that every strict Nash equilibrium is stochastically stable; therefore, in the long run we should not observe the emergence of any particular pattern of behavior, as suggested by the experimental evidence. The model is also compatible with the experimental evidence provided by Goeree and Holt (2005)

AIRO Breast Cancer Group Best Clinical Practice 2022 Update

Introduction: Breast cancer is the most common tumor in women and represents the leading cause of cancer death. Radiation therapy plays a key-role in the treatment of all breast cancer stages. Therefore, the adoption of evidence-based treatments is warranted, to ensure equity of access and standardization of care in clinical practice.Method: This national document on the highest evidence-based available data was developed and endorsed by the Italian Association of Radiation and Clinical Oncology (AIRO) Breast Cancer Group.We analyzed literature data regarding breast radiation therapy, using the SIGN (Scottish Intercollegiate Guidelines Network) methodology (www.sign.ac.uk). Updated findings from the literature were examined, including the highest levels of evidence (meta-analyses, randomized trials, and international guidelines) with a significant impact on clinical practice. The document deals with the role of radiation therapy in the treatment of primary breast cancer, local relapse, and metastatic disease, with focus on diagnosis, staging, local and systemic therapies, and follow up. Information is given on indications, techniques, total doses, and fractionations.Results: An extensive literature review from 2013 to 2021 was performed. The work was organized according to a general index of different topics and most chapters included individual questions and, when possible, synoptic and summary tables. Indications for radiation therapy in breast cancer were examined and integrated with other oncological treatments. A total of 50 questions were analyzed and answered.Four large areas of interest were investigated: (1) general strategy (multidisciplinary approach, contraindications, preliminary assessments, staging and management of patients with electronic devices); (2) systemic therapy (primary, adjuvant, in metastatic setting); (3) clinical aspects (invasive, non-invasive and micro-invasive carcinoma; particular situations such as young and elderly patients, breast cancer in males and cancer during pregnancy; follow up with possible acute and late toxicities; loco-regional relapse and metastatic disease); (4) technical aspects (radiation after conservative surgery or mastectomy, indications for boost, lymph node radiotherapy and partial breast irradiation).Appendixes about tumor bed boost and breast and lymph nodes contouring were implemented, including a dedicated web application. The scientific work was reviewed and validated by an expert group of breast cancer key-opinion leaders.Conclusions: Optimal breast cancer management requires a multidisciplinary approach sharing therapeutic strategies with the other involved specialists and the patient, within a coordinated and dedicated clinical path. In recent years, the high-level quality radiation therapy has shown a significant impact on local control and survival of breast cancer patients. Therefore, it is necessary to offer and guarantee accurate treatments according to the best standards of evidence-based medicine

Apprendimento nella teoria dei giochi: il fictitious play

Dottorato di ricerca in economia politica. 9. Ciclo. Coordinatore Franck Hann. Relatore M. DardiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

The evolution of conventions in minimum effort games

The literature on minimum effort game has been concerned with a symmetric game with linear payoff functions. The main aim of the present paper is to study the coordination problem arising in a not necessarily symmetric minimum effort game with two players. The sources of asymmetry can be twofold: the productivity of effort and the distribution of the join output. To select among the Pareto ranked equilibria we use the stochastic stability criterion. We show that, for any configuration parameters, the set of stochastically stable equilibria coincides with the set of potential maximizers. We also show that when the disutility of effort is linear, the Pareto dominant equilibrium is stochastically stable provided that the distributive parameter belongs to a well defined range. When instead the disutility of effort is nonlinear no distributive arguments can be used to succesfully affect the selection process. Lastly we prove that the connection between stochastic stability and maximum potential can fail when more than two agents are considered

Egalitarianism: an evolutionary perspective

Two parties bargain over a pie, the size of which is determined by their previous investment decisions. Investment costs are heterogenoeus. The bargaining rule is sensitive to investment behavior. Our main result is that egalitarianism is more likely to emerge in situations in which private property over the fruits of one\u2019s own independent investment is not secured