Refinement of defection strategies stabilizes cooperation

Cooperation among unrelated individuals is an enduring evolutionary riddle and a number of possible solutions have been suggested. Most of these suggestions attempt to refine cooperative strategies, while little attention is given to the fact that novel defection strategies can also evolve in the population. Especially in the presence of punishment to the defectors and public knowledge of strategies employed by the players, a defecting strategy that avoids getting punished by selectively cooperating only with the punishers can get a selective benefit over non-conditional defectors. Furthermore, if punishment ensures cooperation from such discriminating defectors, defectors who punish other defectors can evolve as well. We show that such discriminating and punishing defectors can evolve in the population by natural selection in a Prisoner’s Dilemma game scenario, even if discrimination is a costly act. These refined defection strategies destabilize unconditional defectors. They themselves are, however, unstable in the population. Discriminating defectors give selective benefit to the punishers in the presence of non-punishers by cooperating with them and defecting with others. However, since these players also defect with other discriminators they suffer fitness loss in the pure population. Among the punishers, punishing cooperators always benefit in contrast to the punishing defectors, as the latter not only defect with other punishing defectors but also punish them and get punished. As a consequence of both these scenarios, punishing cooperators get stabilized in the population. We thus show ironically that refined defection strategies stabilize cooperation. Furthermore, cooperation stabilized by such defectors can work under a wide range of initial conditions and is robust to mistakes.

Modeling the role of competition and cooperation in the evolution of katydid acoustic synchrony

The precise timing of individual signals in response to those of signaling neighbors is seen in many animal species. Synchrony is the most striking of the resultant timing patterns. One of the best examples of acoustic synchrony is in katydid choruses where males produce chirps with a high degree of temporal overlap. Cooperative hypotheses that speculate on the evolutionary origins of acousti synchrony include the preservation of the species-specific call pattern, reduced predation risks, and increased call intensity. An alternative suggestion is that synchrony evolved as an epiphenomenon of competition between males in response to a female preference for chirps that lead other chirps. Previous models investigating the evolutionary origins of synchrony focused only on intrasexual competitive interactions. We investigated both competitive and cooperative hypotheses for the evolution of synchrony in the katydid Mecopoda ``Chirper'' using physiologically and ecologically realistic simulation models incorporating the natural variation in call features, ecology, female preferences, and spacing patterns, specifically aggregation. We found that although a female preference for leading chirps enables synchronous males to have some selective advantage, it is the female preference for the increased intensity of aggregations of synchronous males that enables synchrony to evolve as an evolutionarily stable strategy.

Strike Hard, Strike Sure - Operation Musketeer : British Military Planning during the Suez Crisis, 1956

This study analyses British military planning and actions during the Suez Crisis in 1956. It seeks to find military reasons for the change of concepts during the planning and compares these reasons with the tactical doctrines of the time. The thesis takes extensive advantage of military documents preserved in the National Archives, London. In order to expand the understanding of the exchange of views during the planning process, the private papers of high ranking military officials have also been consulted. French military documents preserved in the Service Historique de la Defence, Paris, have provided an important point of comparison. The Suez Crisis caught the British armed forces in the middle of a transition phase. The main objective of the armed forces was to establish a credible deterrence against the Soviet Union. However, due to overseas commitments the Middle East playing a paramount role because of its economic importance the armed forces were compelled to also prepare for Limited War and the Cold War. The armed forces were not fully prepared to meet this demand. The Middle Eastern garrison was being re-organised after the withdrawal from the Canal Base and the concept for a strategic reserve was unimplemented. The tactical doctrines of the time were based on experiences from the Second World War. As a result, the British view of amphibious operations and the subsequent campaigns emphasised careful planning, mastery of the sea and the air, sufficient superiority in numbers and firepower, centralised command and extensive administrative preparations. The British military had realized that Nasser could nationalise the Suez Canal and prepared an outline plan to meet this contingency. Although the plan was nothing more than a concept, it was accepted as a basis for further planning when the Canal was nationalised at the end of July. This plan was short-lived. The nominated Task Force Commanders shifted the landing site from Port Said to Alexandria because it enabled faster expansion of the bridgehead. In addition, further operations towards Cairo the hub of Nasser s power would be easier to conduct. The operational concept can be described as being traditional and was in accordance with the amphibious warfare doctrine. This plan was completely changed at the beginning of September. Apparently, General Charles Keightley, the Commander-in-Chief, and the Chairman of the Chiefs of Staff Committee developed the idea of prolonged aerial operations. The essence of the concept was to break the Egyptian will to resist by attacking the oil facilities, the transportation system and the armed forces. This victory through air concept would be supported by carefully planned psychological operations. This concept was in accordance with the Royal Air Force doctrine, which promoted a bomber offensive against selected target categories. General Keightley s plan was accepted despite suspicions at every planning level. The Joint Planning Staff and the Task Force Commanders opposed the concept from the beginning to the end because of its unpredictability. There was no information that suggested the bombing would persuade the Egyptians to submit. This problem was worsened by the fact that British intelligence was unable to provide reliable strategic information. The Task Force Commanders, who were responsible for the tactical plans, were not able to change Keightley s mind, but the concept was expanded to include a traditional amphibious assault on Port Said due to their resistance. The bombing campaign was never tested as the Royal Air Force was denied authorisation to destroy the transportation and oil targets. The Chiefs of Staff and General Keightley were too slow to realise that the execution of the plan depended on the determination of the Prime Minister. However, poor health, a lack of American and domestic support and the indecisiveness of the military had ruined Eden s resolve. In the end, a very traditional amphibious assault, which was bound to succeed at the tactical level but fail at the strategic level, was launched against Port Said.

The story of … the military jacket

Fashion and war don’t seem an obvious pairing, but the military jacket is a fashion staple. It may take the form of a double-breasted dress uniform with brass buttons and epaulettes, trimmed in rock star braid, or it may be a khaki combat jacket, worn with Doc Martens and a scowl. Here I explore how these two forms of the military jacket were frogmarched into fashion...

Ajatuksista operaatioiksi : Suomen armeijan hyökkäysoperaatioiden suunnittelu jatkosodassa

In the research on the Continuation War, interest in the events themselves had exceeded the interest in military planning. Careful consideration has not been given to the planning process and the options that were available. This study shows how the planning of these operations was carried out and identifies the persons responsible. Contrary to earlier research this study shows that persons other than Field-Marshal Carl Gustaf Mannerheim and Quartermaster-General Aksel Airo took part in the planning. Furthermore, the plan was to carry out the operations further east than was ultimately done. The operation plans were coordinated by the Operations Department of Headquarters, which had the opportunity to influence on both Mannerheim and Airo. Part of the actual planning was made outside Headquarters, but final decisions were taken at Headquarters. It is worth observing that many times Mannerheim asked President Risto Ryti for his opinion concerning these operations. The Germans tried to influence the Finnish plans, but the Finns took their decisions independently, although they took German requests into account. It is well-known that the attack by the Finnish forces was stopped at the end of the year 1941. It is less well-known that the Finns planned new attacks until the autumn of 1942. At that point the Finns were convinced that the Germans would lose the war. The Finns were thus prepared to keep advancing should the Germans progress in the direction of Leningrad. This study shows that the Finnish military leaders worked for Finland s own plans and their cooperation with the Germans was directed to achieving this goal. In other words, Finland tried expand eastward with the help of the Germans. This purpose was particularly evident in the planning of the operations in the Hanko district and the Karelian Isthmus in the summer and autumn of 1941, in the Sorokka district in the spring of 1942 and around Lake Ladoga in the summer and autumn of 1942. The Finns reduced their activities when Germans took over responsibility for the operations. However, at the same time the Finns tried to support Germans in passive ways. The Finns justified the decrease in their activities with lack of Finnish forces and numerous defeats. Earlier research has shown that Finland was an active operator in the Continuation War and tried to take back the areas lost in the Winter War. In this study that view becomes more precise and clear especially with regard to Field-Marshal Mannerheim and other high military leaders. There is clear indication that the Finns would have attacked much further east had a German success made such an attack possible.

Evolution of cooperation by reciprocation within structured demes

The iterative two-person Prisoners’ Dilemma game has been generalised to theN-person case. The evolution of cooperation is explored by matching the Tit For Tat (TFT) strategy (Axelrod and Hamilton 1981) against the selfish strategy. Extension of TFT toN-person situations yields a graded set of strategies from the softest TFT, which continues cooperation even if only one of the opponents reciprocates it, to the hardest, which would do so only when all the remaining opponents cooperate. The hardest TFT can go to fixation against the selfish strategy provided it crosses a threshold frequencypc. All the other TFT are invadable by the selfish (D) or the pure defector strategy, while none can invadeD. Yet, provided a thresholdpc is crossed, they can coexist stably withD. AsN, the size of the group increases, the threshold pc also increases, indicating that the evolution of cooperation is more difficult for larger groups. Under certain conditions, only the soft TFT can coexist stably against the selfish strategyD, while the harder ones cannot. An interesting possibility of a complete takeover of the selfish population by successive invasions by harder and harder TFT strategies is also presented.

Labor-Management Cooperation

[Excerpt] In analyzing labor-management cooperation, it is important to be clear on what it is not. It is not an absence of strikes or conflict. Cooperation is not synonymous with industrial peace. Cooperation may take place even when bargaining leads to work stoppages; conversely, the mere absence of strikes is no evidence that there is labor-management cooperation. In the current period, there is a tendency to equate concessionary bargaining with labor-management cooperation. Demand for and acceptance of "givebacks" reflect economic pressures and relative bargaining strength and ought not to be interpreted as evidence of a cooperative relationship.

Portrait of Surgeon Major Dr. Meyer of Dueren (Rhineland) in military uniform Portraits Men

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Portrait of Surgeon Major Dr. Bing of Nuernberg in his military uniform Portraits Men

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Reproduction of portrait of field chaplain Rabbi Dr. Sali Levi Military; World War I; Portraits

Feldrabbiner Dr. Sali Lewi, Breslau

Portrait of Ernst Gottschalk (seated second row center) with eight unidentified soldiers; Rendsburg, Germany. Military Portraits groups

Morgen hat Reserve Ruh / Auf Wiedersehen / Beste Gruesse; postcard signer Gottschalk; addressee: L Nurzinsky, Altona-Othmarschen, Aidikes Str.

Portrait of Leopold Meyerhof in his World War I officer's uniform Military; World War I; Portraits

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Portrait of Leo Baeck as military chaplain Military; World War I; Portraits

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Leo Baeck with unidentified soldiers Military; World War I; Portraits Groups

Center May 2000