We show that standard axioms determine uniquely the marginal cost pricing rule on homogeneous, convex and continuously differentiable cost functions.

We derive an explicit formula for a marginalist and efficient value for a TU game which possesses the -player property and is either continuous or monotonic. We show that every such a value has to be additive and covariant as well. It follows that the set of all marginalist, efficient, and monotonic values possessing the -player property coincides with the set of random-order values, and thereby the last statement provides an axiomatization without the linearity axiom for the latter which is similar to that of Young for the Shapley value. Another axiomatization without linearity for random-order values is provided by marginalism, efficiency, monotonicity, and covariance. Keywords: Transferable utility game; Value; Axiomatic characterization; Efficiency; Mar- ginalism

This paper considers the set of Lorenz-maximal imputations in the core of a balanced cooperative game as a solution concept. It is shown that the Lorenz-solution concept satisfies a number of suitable properties such as desirability, continuity and the reduced game property. Moreover, the paper considers alternative characterizations where it is shown that Lorenz-fairness is tantamount to the existence of an additive, strictly increasing and concave social welfare function. Finally the paper also provides axiomatic characterizations as well as two examples of application.

We develop an axiomatization of a single-valued solution for finite-type perfectly competitive economies. The solution is a competitive payoff selection. Our axioms are similar to those of Dubey and Neyman for solutions of differentiable economies, and they give rise to the Mertens value.

We show that for voting systems containing at least three voters the set of all marginalist, efficient, and monotonic power indices possessing the -player property coincide with the set of random-order power indices, and thereby the last statement spreads to simple games the result of Khmelnitskaya concerning an axiomatization without the linearity assumption for random-order values for the entire class of TU games. We also give evidence that every marginalist, efficient, and symmetric power index is just the Shapley-Shubik power index what provides an axiomatization for the latter similar to that of Young for the Shapley value; in symmetric case there is no restriction for a number of players to be not less than three. Keywords: Simple game; Power index; Axiomatic characterization; Efficiency; Marginalism

{Let X_i>=0 be independent

For excludable public goods, we propose simple mechanisms to uniquely implement a (core) stable and efficient production and cost-sharing outcome: consumers are asked to announce sequentially their minimal requested level of public good and a subscription towards its production. In one mechanism the subscriptions are order-independent and thus symmetric. The equilibrium outcomes induced by our mechanisms are immune to strategic deviations by coalitions. Keywords: Excludable public good, demand-subscription mechanism, implementation, stand alone core, coalition formation, strong equilibrium. Journal of Economic Literature Classification Numbers: H41, C72, D78.

We prove that multidimensional generalized median voter schemes are coalition-proof.

This paper characterizes social welfare orderings for different scales of individual utility measurement in distinct population subgroups. Different combinations of ordinal, interval, ratio, and translation scales are studied. We consider situations when utility comparisons among subgroups of individuals by unit and/or zeropoint can or cannot be made, that is when subgroup scales are dependent or independent. We show that for combinations of independent subgroup scales, every corresponding social ordering is fully determined by the opinions of only one subgroup of individuals and is in accordance with the measurement scales of its members' utilities. We also investigate social orderings admissible given various combinations of arbitrary ratio scales that combine individual utilities from different subgroups.

A paper of Witztum, Rips and Rosenberg in this journal in 1994 made the extraordinary claim that the Hebrew text of the Book of Genesis encodes events which did not occur until millennia after the text was written. In reply, we argue that Witztum, Rips and Rosenberg's case is fatally defective, indeed that their result merely reflects on the choices made in designing their experiment and collecting the data for it. We present extensive evidence in support of that conclusion. We also report on many new experiments of our own, all of which failed to detect the alleged phenomenon.

This paper analyzes symmetric, single item auctions in the private values framework, with buyers whose preferences satisfy the axioms of Yaari's (1987) dual theory of choice under risk. It is shown that when their valuations are independently and identically distributed, buyers are indifferent among all the auctions contained in a big family of mechanisms that includes the standard auctions. It is also shown that in the linear equilibria of the sealed bid double auction, as the degree of players' risk aversion grows arbitrarily large, the ex post inefficiency of the mechanism tends to vanish. JEL Classification Numbers: D44; D81

Teachers of history note that pupils are often surprised to learn that a certain event in Europe happened at the same time as another in America, since to them the latter appears to have happened more recently. The validity of this anecdotal observation is supported by an experiment. This bias is explained by noting that America is The New World, while Europe is The Old World. Independent verification is offerred for this explanation. It is shown that the accessibility principle (i.e. that better known events appear more recent than less well known ones) neither accounts for the bias nor even operates with our stimuli.'An earlier version of this paper, titled The Europe-America Bias:' Where a historical event occurred affects when people think it occurred, was published later,'in 2005, in Advances in Psychology Research (S. P. Shohov, ed.), vol. 33, 39-63.' It is fuller, and in the link todp208 it'follows the version published in Psychological Science in 2002.

This paper analyzes a two-stage sealed-bid auction that is frequently employed in privatization, takeover, and merger and acquisition contests. This auction format yields the same expected revenue as the open ascending (English) auction, yet is less susceptible to preemptive bidding and collusion.

We propose a new and simple adaptive procedure for playing a game: " regretmatching." In this procedure, players depart from their current play with probabilities that are proportional to measures of regret for not having used other strategies in the past. It is shown that our adaptive procedure guarantees that, with probability one, the empirical distributions of play converge to the set of correlated equilibria of the game. To compute these regret measures, a player needs to know his payoff function and the history of play. We also offer a variation where every player knows only his own realized payoff history ( but not his payoff function).

Naive bumble bees (Bombus terrestris) that did not learn to handle artificial flowers were examined for sampling frequency and duration before giving up. The munber of sample-bouts and the time of each sample-bout were measured, as well as the time in between two subsequent sample-bouts (pauses). This flower-sampling behavior of un successful individual bumble bees was related to the age of the bees, cohort and colony size. Younger bees sampled the flowers more frequently but stayed a shorter time each sample-bout than older bees. The duration of each separate pause was longer for older bees as well. The total sampling-time before giving up tended to be higher for the older bees. For all bees the subsequent sample-bouts showed a decrease in duration, while the duration of each subsequent pause increased. This was possibly caused by a negative re-enforcement by the unsuccessful samples. The higher unsuccessful sample-frequency of the younger bees could beconsidered a part ofa first orientation and learning process of flower handling. Therefore this sampling could influence the future behavior of young bees and might result in a higher capability of handling comlex flowers. Finally it should be emphasized that these results are our first prove of age-related learning and it is suggested that research along this line could result in more evidence of age-related foraging behavior.

Within this series of papers we plan to exhibit to any noncooperative game in strategic or normal form a 'canonical' representation in extensive form that preserves all symmetries of the game. The operation defined this way will respect the restriction of games to subgames and yield a minimal total rank of the tree involved. Moreover, by the above requirements the 'canonical extensive game form' will be uniquely defined. Part I is dealing with isomorphisms of game forms and games. An auto- morphism of the game is called motion. A symmetry of a game is a permuta- tion which can be augmented to a motion. Some results on the existence of symmetry groups are presented. The context to the notion of symmetry for coalitional games is exhibited.

The consistent value is an extension of the Shapley value to the class of games with non-transferable utility In this paper, the consistent value will be characterized for market games with a continuum of players of 2 types. We will show that for such games the consistent value need not belong to the core, and conditions under which there is equivalence between the two concepts will be given.

We consider the structure of the set of correlated equilibria for games with a large number n of players. Since the number of equilibrium constraints grows slower than the number of strategy arrays, it might be conjectured that the set of correlated equilibra is large. In this paper we show (1) that the average relative measure of the solution set is smaller than 2^-n, but also (2) that the solution set contains a number c^n of equilibria having disjoint supports with a probability going to I as n grows large. The proof of the latter result hinges on a combinatorial result on the number of nonnegative linear combinations of vectors representing a given point, which may be of independent interest.

Large flowers often contain larger nectar rewards, and receive more pollinator visits, than small flowers. We studied behavioural mechanisms for the formation of flower preferencce in bumblebees in a two-phase laboratory experiment. Flower-naive Bombus terrestris (L.) foraged on artificial flowers that bore either a big (3.8 cm diameter) or a small (2.7 cm diameter) display of a uniform colour. Only flowers of one display size contained nectar rewards. We changed the display colour and the locations of big and small flowers in the second experimental phase. We recorded the bees' choices in both trials. 41% of the bees made their first visit to a small flower. The bees learned to associate display size with food reward, and chose rewarding flowers with > 85% accuracy by the end of each learning trial. Some learning occured within the bees' first three flower visits. Learning of the size-reward association was equally good for big and small displays in the first trial, but better for small displays in the second trial. Formation of size-reward associations followed a similar course in both trials. This suggests that the bees did not apply their experience from the first learning trial to the new situation of the second trial. Rather, they treated each phase of the experiment as an independent learning trial. We suggest that pollinators from flower-size preferences through associative learning, and that they may not transfer the concept of "flower size" from one situation to another. Implications for the possible evolution of floral displays are discussed.

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