The evolution of cooperation by social exclusion Sasaki, Tatsuya; Uchida, Satoshi
Proceedings - Royal Society. Biological sciences/Proceedings - Royal Society. Biological Sciences,
02/2013, Letnik:
280, Številka:
1752
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The exclusion of freeriders from common privileges or public acceptance is widely found in the real world. Current models on the evolution of cooperation with incentives mostly assume peer ...sanctioning, whereby a punisher imposes penalties on freeriders at a cost to itself. It is well known that such costly punishment has two substantial difficulties. First, a rare punishing cooperator barely subverts the asocial society of freeriders, and second, natural selection often eliminates punishing cooperators in the presence of non-punishing cooperators (namely, ‘second-order’ freeriders). We present a game-theoretical model of social exclusion in which a punishing cooperator can exclude freeriders from benefit sharing. We show that such social exclusion can overcome the above-mentioned difficulties even if it is costly and stochastic. The results do not require a genetic relationship, repeated interaction, reputation or group selection. Instead, only a limited number of freeriders are required to prevent the second-order freeriders from eroding the social immune system.
In 2009, Gradwohl, Naor, Pinkas, and Rothblum proposed physical zero-knowledge proof protocols for Sudoku. That is, for a puzzle instance of Sudoku, their excellent protocols allow a prover to ...convince a verifier that there is a solution to the Sudoku puzzle and the prover knows it, without revealing any information about the solution. The possible drawback is that the existing protocols have an extractability error with a non-zero probability, or need special cards (such as scratch-off cards). Thus, in this study, we propose new protocols to perform zero-knowledge proof of knowledge for Sudoku using a normal deck of playing cards with no extractability error. Our protocols can be easily implemented by humans with a reasonable number of playing cards.
Cell therapy for Parkinson’s disease (PD) began in 1979 with the transplantation of fetal rat dopamine-containing neurons that improved motor abnormalities in the PD rat model with good survival of ...grafts and axonal outgrowth. Thirty years have passed since the 2 clinical trials using cell transplantation for PD patients were first reported. Recently, cell therapy is expected to develop as a realistic treatment option for PD patients owing to the advancement of biotechnology represented by pluripotent stem cells. Medication using levodopa, surgery including deep brain stimulation, and rehabilitation have all been established as current therapeutic strategies. Strong therapeutic effects have been demonstrated by these treatment methods, but they have been unable to stop the progression of the disease. Fortunately, cell therapy might be a key for true neurorestoration. This review article describes the historical development of cell therapy for PD, the current status of cell therapy, and the future direction of this treatment method.
Indirect reciprocity is a major mechanism in the maintenance of cooperation among unrelated individuals. Indirect reciprocity leads to conditional cooperation according to social norms that ...discriminate the good (those who deserve to be rewarded with help) and the bad (those who should be punished by refusal of help). Despite intensive research, however, there is no definitive consensus on what social norms best promote cooperation through indirect reciprocity, and it remains unclear even how those who refuse to help the bad should be assessed. Here, we propose a new simple norm called "Staying" that prescribes abstaining from assessment. Under the Staying norm, the image of the person who makes the decision to give help stays the same as in the last assessment if the person on the receiving end has a bad image. In this case, the choice about whether or not to give help to the potential receiver does not affect the image of the potential giver. We analyze the Staying norm in terms of evolutionary game theory and demonstrate that Staying is most effective in establishing cooperation compared to the prevailing social norms, which rely on constant monitoring and unconditional assessment. The application of Staying suggests that the strict application of moral judgment is limited.
Card-Based Physical Zero-Knowledge Proof for Kakuro MIYAHARA, Daiki; SASAKI, Tatsuya; MIZUKI, Takaaki ...
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences,
09/2019, Letnik:
E102.A, Številka:
9
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Kakuro is a popular logic puzzle, in which a player fills in all empty squares with digits from 1 to 9 so that the sum of digits in each (horizontal or vertical) line is equal to a given number, ...called a clue, and digits in each line are all different. In 2016, Bultel, Dreier, Dumas, and Lafourcade proposed a physical zero-knowledge proof protocol for Kakuro using a deck of cards; their proposed protocol enables a prover to convince a verifier that the prover knows the solution of a Kakuro puzzle without revealing any information about the solution. One possible drawback of their protocol would be that the protocol is not perfectly extractable, implying that a prover who does not know the solution can convince a verifier with a small probability; therefore, one has to repeat the protocol to make such an error become negligible. In this paper, to overcome this, we design zero-knowledge proof protocols for Kakuro having perfect extractability property. Our improvement relies on the ideas behind the copy protocols in the field of card-based cryptography. By executing our protocols with a real deck of physical playing cards, humans can practically perform an efficient zero-knowledge proof of knowledge for Kakuro.
Self-interest frequently causes individuals engaged in joint enterprises to choose actions that are counterproductive. Free-riders can invade a society of cooperators, causing a tragedy of the ...commons. Such social dilemmas can be overcome by positive or negative incentives. Even though an incentive-providing institution may protect a cooperative society from invasion by free-riders, it cannot always convert a society of free-riders to cooperation. In the latter case, both norms, cooperation and defection, are stable: To avoid a collapse to full defection, cooperators must be sufficiently numerous initially. A society of free-riders is then caught in a social trap, and the institution is unable to provide an escape, except at a high, possibly prohibitive cost. Here, we analyze the interplay of (a) incentives provided by institutions and (b) the effects of voluntary participation. We show that this combination fundamentally improves the efficiency of incentives. In particular, optional participation allows institutions punishing free-riders to overcome the social dilemma at a much lower cost, and to promote a globally stable regime of cooperation. This removes the social trap and implies that whenever a society of cooperators cannot be invaded by free-riders, it will necessarily become established in the long run, through social learning, irrespective of the initial number of cooperators. We also demonstrate that punishing provides a "lighter touch" than rewarding, guaranteeing full cooperation at considerably lower cost.
•We analyze a model of indirect reciprocity, a key mechanism to sustain cooperation.•We incorporate assessment error and private information in the model.•We show that stern-judging, one of the ...best-known assessment models, collapses.•The proportion of “good” individuals in a population with stern-judging is 1/2.
Stern-judging is one of the best-known assessment rules in indirect reciprocity. Indirect reciprocity is a fundamental mechanism for the evolution of cooperation. It relies on mutual monitoring and assessments, i.e., individuals judge, following their own assessment rules, whether other individuals are “good” or “bad” according to information on their past behaviors. Among many assessment rules, stern-judging is known to provide stable cooperation in a population, as observed when all members in the population know all about others’ behaviors (public information case) and when the members never commit an assessment error. In this paper, the effect of assessment error and private information on stern-judging is investigated. By analyzing the image matrix, which describes who is good in the eyes of whom in the population, we analytically show that private information and assessment error cause the collapse of stern-judging: all individuals assess other individuals as “good” at random with a probability of 1/2.
Punishment is a popular tool when governing commons in situations where free riders would otherwise take over. It is well known that sanctioning systems, such as the police and courts, are costly and ...thus can suffer from those who free ride on other's efforts to maintain the sanctioning systems (second-order free riders). Previous game-theory studies showed that if populations are very large, pool punishment rarely emerges in public good games, even when participation is optional, because of second-order free riders. Here we show that a matching fund for rewarding cooperation leads to the emergence of pool punishment, despite the presence of second-order free riders. We demonstrate that reward funds can pave the way for a transition from a population of free riders to a population of pool punishers. A key factor in promoting the transition is also to reward those who contribute to pool punishment, yet not abstaining from participation. Reward funds eventually vanish in raising pool punishment, which is sustainable by punishing the second-order free riders. This suggests that considering the interdependence of reward and punishment may help to better understand the origins and transitions of social norms and institutions.
In pediatric moyamoya disease, there have been few reports of the risk factors for preoperative cerebral infarction, especially during the waiting period before surgery. The clinical and radiological ...findings of surgically treated pediatric moyamoya patients were evaluated to analyze the risk factors for cerebral infarction seen from onset to surgery.
Between August 2003 and September 2019, 120 hemispheres of 71 patients under 18 years of age with moyamoya disease were surgically treated by direct and indirect bypass procedures. The mean age of all surgical hemispheres at diagnosis was 6.7±3.9 years (6 months–17 years). The potential risk factors for preoperative infarction were examined statistically.
Multivariate logistic regression analysis showed that risk factors for infarction at the time of diagnosis were age at diagnosis (odds ratio OR, 0.68 95% CI, 0.57–0.82; P<0.0001) and the magnetic resonance angiography (MRA) score (OR, 2.29 95% CI, 1.40–3.75; P=0.001). Univariate analysis showed that risk factors for infarction while waiting for surgery were age at diagnosis (OR, 0.61 95% CI, 0.46–0.80; P<0.0001), the MRA score (OR, 1.75 95% CI, 1.26–2.41; P=0.0003), and onset of infarction (OR, 40.4 95% CI, 5.08–322.3; P<0.0001). Multiple comparisons showed that patients under 4 years of age were at a significantly high risk of infarction at the time of diagnosis and while waiting for surgery. Time from diagnosis to surgery of >2 months was a significant risk factor for infarction while waiting for surgery in patients under 6 years of age.
Young age at diagnosis and a high MRA score may be associated with rapid disease progression and result in preoperative infarction. We recommend that surgery be performed within 2 months of diagnosis for the patients under 4 years of age with a high MRA score (>5) and cerebral infarction. Further study is needed to define the optimal timing of surgery.
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