We consider the class of hyperplane coalition games (H-games): the feasible set of each coalition is a half-space, with a slope that may vary from one coalition to another. H-games have turned out in various approaches to the value of general non-transferable utility (NTU) games. In this paper we introduce a simple model – prize games – that generates the hyperplane games. next, we provide an axiomatization for the Maschler & Owen (1989) consistent value of H-games.

We present here a model of pollination having one species of bees and several species of flowers. Each flower species is distinguished by its rate of nectar production and the resources it devotes to display. The flowers and bees are assumed to have identical lifetimes that comprise a number of days within a single year. At the start of the year the bees in their naive phase are attracted to flowers according to the relative sizes of the flowers' displays; however, the bees soon become experienced and continually monitor the amounts of the nectar standing crops of each species, altering their visiting habits over time so that they always tend to visit most frequently the flower species having the largest nectar standing crop. This, in turn, tends equalize the nectar standing crop across species. From one year to the next the relative abundance of the flower species can change in accordance with the reproductive success of each species. This, in turn, depends upon the number of visits by bees to the flowers of each species, the amount of energy devoted to reproduction, and the relative abundance of each species in the preceding year. The model described below has been programmed so that it is possible to run simulations. We make no attempt to model the absolute number of bees or of flowers, but do assume the ratio of bees to flowers is the same from one season to the next. Within this model systematic deviations by the bees from apparently optimal foraging policies can be seen, due to monitoring by the bees, and also the ability to survive of large display flowers that produce no nectar ("cheaters") can be explained.

We investigate the ESS's of payoff-irrelevant asymmetric animal conflicts in Selten's (1980) model. We show that these are determined by the symmetric and strict correlated equilibria of the underlying (symmetric) two-person game. More precisely, the set of distributions (on the strategy space) of ESS's coincides with the set of strict and symmetric correlated equilibria (described as distributions). Our result enables us to predict all possible stable payoffs in payoff-irrelevant asymmetric animal conflicts using Aumann's correlated equilibria. Italso enables us to interpret correlated equilibria as solutions to biological conflicts: Nature supplies the correlation device as a phenotypic conditional behavior.

Multiple choice tests that are scored by formula scoring typically include instructions that discourage guessing. In this paper we look at test taking from the normative and descriptive perspectives of judgment and decision theory. We show that for a rational test taker, whose goal is the maximization of expected score, answering is either superior or equivalent to omitting – a fact which follows from the scoring formula. For test takers who are not fully rational, or have goals other than the maximization of expected score, it is very hard to give adequate formula scoring instructions, and the recommen-dation to answer under partial knowledge is problematic (though generally beneficial). Our analysis derives from a critical look at standard assumptions about the epistemic states, response strategies, and strategic motivations of test takers. In conclusion, we endorse the "number right" scoring rule, which discourages omissions, and is robust against variability in respondent motivations, limitations in judgments of uncertainty, and item vagaries.