Regression to the Mean and Judy Benjamin

Van Fraassen's Judy Benjamin problem asks how one ought to update one's credence in A upon receiving evidence of the sort ``A may or may not obtain, but B is k times likelier than C'', where {A,B,C} is a partition. Van Fraassen's solution, in the limiting case of increasing k, recommends a posterior converging to the probability of A conditional on A union B, where P is one's prior probability function. Grove and Halpern, and more recently Douven and Romeijn, have argued that one ought to leave credence in A unchanged, i.e. fixed at P(A). We argue that while the former approach is superior, it brings about a Reflection violation due in part to neglect of a ``regression to the mean'' phenomenon, whereby when C is eliminated by random evidence that leaves A and B alive, the ratio P(A):P(B) ought to drift in the direction of 1:1

The cost of conservative synchronization in parallel discrete event simulations

The performance of a synchronous conservative parallel discrete-event simulation protocol is analyzed. The class of simulation models considered is oriented around a physical domain and possesses a limited ability to predict future behavior. A stochastic model is used to show that as the volume of simulation activity in the model increases relative to a fixed architecture, the complexity of the average per-event overhead due to synchronization, event list manipulation, lookahead calculations, and processor idle time approach the complexity of the average per-event overhead of a serial simulation. The method is therefore within a constant factor of optimal. The analysis demonstrates that on large problems--those for which parallel processing is ideally suited--there is often enough parallel workload so that processors are not usually idle. The viability of the method is also demonstrated empirically, showing how good performance is achieved on large problems using a thirty-two node Intel iPSC/2 distributed memory multiprocessor

Cry of Color, April 1970

Volume 1, No. 1 Subtitle: third world supplementhttps://scholarworks.sjsu.edu/cryofcolor/1000/thumbnail.jp

Visual Arguments and Moral Causes in Charity Advertising: Ethical Considerations

Social advertising often employs persuasive imagery in support of a morally laden cause. These visual arguments can take the form of veridical representations of the given situation or the form of purposeful visual blends. Both visual routes to persuasion have serious ethical issues to confront. In what concerns the purportedly veridical images, controversies about picture retouching and framing have cast many doubts on their success in offering unmediated access to a given reality. Editorial interests have proven far too influential on the destiny of what and how is presented to the audience from the amount of visual material available on a topic. Even when the audience is certain that photos are not doctored, the use of veridical images may be seen as unethical. Their disproportionate affective impact may lead the audience to hold biased opinions, since other concerns may be impossible to capture in a vivid picture. Visual blends may be the answer to this problem, employing the fictional or the figurative to help the viewer grasp the moral anatomy of a given situation. Their generous use of figurative meaning may be seen as their strength and their weakness at the same time. It makes them less likely to face accusations of distorting reality, because they do not claim to be windows on reality per se. At the same time, it makes them vulnerable to interpretations that miss their true point – one might appreciate the artistry of a visual metaphor or a visual pun and fail to consider the statement it makes about a given situation. Contemporary philosophical approaches to the place of visuals in moral persuasion inform my analysis of the use of visual arguments in charity-oriented advertising

Mechanisms for Automated Negotiation in State Oriented Domains

This paper lays part of the groundwork for a domain theory of negotiation, that is, a way of classifying interactions so that it is clear, given a domain, which negotiation mechanisms and strategies are appropriate. We define State Oriented Domains, a general category of interaction. Necessary and sufficient conditions for cooperation are outlined. We use the notion of worth in an altered definition of utility, thus enabling agreements in a wider class of joint-goal reachable situations. An approach is offered for conflict resolution, and it is shown that even in a conflict situation, partial cooperative steps can be taken by interacting agents (that is, agents in fundamental conflict might still agree to cooperate up to a certain point). A Unified Negotiation Protocol (UNP) is developed that can be used in all types of encounters. It is shown that in certain borderline cooperative situations, a partial cooperative agreement (i.e., one that does not achieve all agents' goals) might be preferred by all agents, even though there exists a rational agreement that would achieve all their goals. Finally, we analyze cases where agents have incomplete information on the goals and worth of other agents. First we consider the case where agents' goals are private information, and we analyze what goal declaration strategies the agents might adopt to increase their utility. Then, we consider the situation where the agents' goals (and therefore stand-alone costs) are common knowledge, but the worth they attach to their goals is private information. We introduce two mechanisms, one 'strict', the other 'tolerant', and analyze their affects on the stability and efficiency of negotiation outcomes.Comment: See http://www.jair.org/ for any accompanying file

Informal Insurance in Social Networks

This paper studies informal insurance across networks of individuals. Two characteristics are fundamental to the model developed here: First, informal insurance is a bilateral activity, and rarely involves explicit arrangements across several people. Second, insurance is a social activity, and transfers are often based on norms. In the model studied here, only directly linked agents make transfers to each other, although they are aware of the (aggregate) transfers each makes to third parties. An insurance scheme for the network as a whole is an equilibrium of several interacting bilateral arrangements. This model serves as a starting point for investigating stable insurance networks, in which all agents actually have private incentives to abide by the ongoing insurance arrangement. The resulting analysis shows that network links have two distinct and possibly conflicting roles to play. First, they act as conduits for transfers, and in this way this make better insurance possible. Second, they act as conduits for information, and in this sense they affect the severity of punishments for noncompliance with the scheme. A principal task of this paper is to describe how these two forces interact, and in the process characterize stable networks. The concept of "sparse" networks, in which the removal of certain links increases the number of network components, is crucial in this characterization. As corollaries, we found that both "thickly connected" networks(such as the complete graph) and "thinly connected" networks (such as trees) are likely to be stable, whereas intermediate degrees of connectedness jeopardize stability. Finally, we study in more detail the notion of networks as conduits for transfers, by simply assuming a punishment structure (such as autarky) that is independent of the precise architecture of the tree. This allows us to isolate a bottleneck effect: the presence of certain key agents who act as bridges for several transfers. Bottlenecks are captured well in a feature of trees that we call decomposability, and we show that all decomposable networks have the same stability properties and that these are the least likely to be stable.social networks, informal insurance

Informal Insurance in Social Networks

social networks, informal insurance.

Was the NOAA Panel Correct About Contingent Valuation?

The past few years have seen a highly charged debate about whether contingent valuation (CV) surveys can provide valid economic measures of people's values for environmental resources. In an effort to appraise the validity of CV measures of economic value, a distinguished panel of social scientists, chaired by two Nobel laureates, was established by NOAA, to critically evaluate the validity of CV measures of nonuse value. The Panel provided an extensive set of guidelines for CV survey construction, administration, and analysis, and distinguished a subset of items from their guidelines for special emphasis and described them as burden of proof requirements. Of particular interest was the Panel's requirement that CV surveys demonstrate "responsiveness to the scope of the environmental insult." That demonstration has come to be called a scope test. The paper reports the findings from the first CV study that adheres to the NOAA Panel's guidelines and includes a formal scope test.

Specifying and Refining Internal Operations in Z

Abstract An important aspect in the specification of distributed systems is the role of the internal (or unobservable) operation. Such operations are not part of the interface to the environment (i.e. the user cannot invoke them), however, they are essential to our understanding and correct modelling of the system. In this paper we are interested in the use of the formal specification notation Z for the description of distributed systems. Various conventions have been employed to model internal operations when specifying such systems in Z. If internal operations are distinguished in the specification notation, then refinement needs to deal with internal operations in appropriate ways. Using an example of a telecommunications protocol we show that standard Z refinement is inappropriate for refining a system when internal operations are specified explicitly. We present a generalization of Z refinement, called weak refinement, which treats internal operations differently from observable operations when refining a system. We discuss the role of internal operations in a Z specification, and in particular whether an equivalent specification not containing internal operations can be found. The nature of divergence through livelock is also discussed. Keywords: Z; Refinement; Distributed Systems; Internal Operations; Process Algebras; Concurrency