Credible Deviations Research Articles

Cooperative concurrent games

In rational verification, the aim is to verify which temporal logic properties will obtain in a multi-agent system, under the assumption that agents (“players”) in the system choose strategies for acting that form a game theoretic equilibrium. Preferences are typically defined by assuming that agents act in pursuit of individual goals, specified as temporal logic formulae. To date, rational verification has been studied using non-cooperative solution concepts—Nash equilibrium and refinements thereof. Such non-cooperative solution concepts assume that there is no possibility of agents forming binding agreements to cooperate, and as such they are restricted in their applicability. In this article, we extend rational verification to cooperative solution concepts, as studied in the field of cooperative game theory. We focus on the core, as this is the most fundamental (and most widely studied) cooperative solution concept. We begin by presenting a variant of the core that seems well-suited to the concurrent game setting, and we show that this version of the core can be characterised using ATL⁎. We then study the computational complexity of key decision problems associated with the core, which range from problems in PSpace to problems in 3ExpTime. We also investigate conditions that are sufficient to ensure that the core is non-empty, and explore when it is invariant under bisimilarity. We then introduce and study a number of variants of the main definition of the core, leading to the issue of credible deviations, and to stronger notions of collective stable behaviour. Finally, we study cooperative rational verification using an alternative model of preferences, in which players seek to maximise the mean-payoff they obtain over an infinite play in games where quantitative information is allowed.

Models of Analysis of Credible Deviation from Speed Limits on Two‐Lane Roads of Bosnia and Herzegovina

Any deviation of speed in a traffic flow from a speed limit represents a potential risk of traffic accidents, so speed management appears as an imperative. However, an inadequately set speed limit often causes drivers’ noncompliance to it in the conditions of real traffic flow. By determining the value of exceeding the speed limit according to vehicle classes, it is possible to recommend a credible speeding value that can be considered credible up to a value above the speed limit. In this paper, deterministic multistep mathematical models of speed deviation from the speed limit as a function of longitudinal gradient for the proposed vehicle classes were developed. A total of 11 measuring sections with different traffic flow types were analyzed. Based on a detailed analysis of speeding, models for the deviation of the 15th, 50th, and 85th percentiles were obtained, with the aim of adjusting the credible deviation to control measures. The results obtained in this study were compared with a survey of traffic flow speeding on two‐lane roads conducted in Serbia.

Immunity to credible deviations from the truth

We study a notion of non-manipulability by groups, based on the idea that only some agreements among potential manipulators may be credible. The derived notion of immunity to credible manipulations by groups is intermediate between individual and group strategy-proofness. Our main non-recursive definition turns out to be equivalent, in our context, to the requirement that truthful preference revelation should be a strong coalition-proof equilibrium, as recursively defined by Peleg and Sudhölter (1998, 1999). We provide characterizations of strategy-proof rules separating those that satisfy it from those that do not for a large family of public good decision problems.

Immunity to Credible Deviations from the Truth

We introduce a new notion of non-manipulability by groups, based on the idea that some of the agreements among a set of potential manipulators may be credible, while others may not. The derived notion of immunity to credible manipulations by groups is intermediate between individual and group strategy-proofness. We show that our new concept has bite, by applying it to the analysis of a large family of public good decision problems in separable environments, where there exist many attractive strategy-proof rules that are, however, manipulable by groups. In these environments we show that some of these rules are indeed, immune to credible group manipulations, while others are not. We provide characterization results that separate these two classes.

Equilibrium selection in experimental cheap talk games

In the past, many refinements have been proposed to select equilibria in cheap talk games. Usually, these refinements were motivated by a discussion of how rational agents would reason in some particular cheap talk games. In this paper, we propose a new refinement and stability measure that is intended to predict actual behavior in a wide range of cheap talk games. According to our Average Credible Deviation Criterion (ACDC), the stability of an equilibrium is determined by the frequency and size of credible deviations. ACDC organizes the results from several cheap talk experiments in which behavior converges to equilibrium, even in cases where other criteria do not make a prediction.

AB1044 Toxic effects of toluene vapor on growth of different bones: Tibia, vertebra, hip bone

BackgroundNontraumatic diseases of the skeletal system, such as osteoporosis, have reached epidemic proportions today. Toxic environmental factors play an important role in the pathogenesis of, but their influence has been...

For those about to talk we salute you: an experimental study of credible deviations and ACDC

We test the Average Credible Deviation Criterion (ACDC), a stability measure and refinement for cheap talk equilibria introduced in De Groot Ruiz et al. (Equilibrium selection in cheap talk games: ACDC rocks when other criteria remain silent, Working paper, University of Amsterdam 2012a). ACDC has been shown to be predictive under general conditions and to organize data well in previous experiments meant to test other concepts. In a new experimental setting, we provide the first systematic test of whether and to which degree credible deviations matter for the stability of cheap talk equilibria. Our principal experimental result is that in a setting where existing concepts are silent, credible deviations matter and matter gradually, as predicted by ACDC.

Information, Uncertainty and the Core

How are contracts formed when agents face uncertainty, have asymmetric information and cannot write binding agreements? In this paper we propose a solution to this problem. Agents can discuss state-contingent allocations but cannot write binding contracts. At any stage in the contract formation phase a coalition of agents can deviate and choose to form agreements amongst themselves. However, we restrict these deviations to be credible: meaning that no sub-coalition has a further credible deviation. In this context, we propose the coarse and fine weak sequential cores as solution concepts and sufficient conditions for the non-emptiness of these solution concepts are provided.

Equilibrium Selection in Cheap Talk Games: ACDC Rocks When Other Criteria Remain Silent

In the past, many refinements have been proposed to select equilibria in cheap talk games. Usually, these refinements were motivated by a discussion of how rational agents would reason in some particular cheap talk games. In this paper, we propose a behavioral refinement and stability measure that is meant to predict actual behavior in a wide range of cheap talk games. According to our Average Credible Deviation Criterion (ACDC), the stability of an equilibrium is determined by the frequency and size of credible deviations. ACDC organizes the results from cheap talk experiments well, even in cases where other criteria remain silent.

An Experimental Study of Credible Deviations and ACDC

We test the Average Credible Deviation Criterion (ACDC), a stability measure and refinement for cheap talk equilibria introduced in De Groot Ruiz, Offerman & Onderstal (2011b). ACDC has been shown to be predictive under general conditions and to organize data well in previous experiments meant to test other concepts. This experiment provides the first systematic test of whether and to which degree credible deviations matter for the stability of cheap talk equilibria. Furthermore, it tests ACDC in a new setting. We also introduce a neologism dynamic to explain the main dynamic characteristics of our data. Our main result is that credible deviations matter and matter gradually, as predicted by ACDC. In addition, our data support the predictions of ACDC in settings where existing concepts are silent. Finally, we test the prediction derived in De Groot Ruiz, Offerman & Onderstal (2011a) about bargaining power and information transmission. We find that, as predicted, less information is transmitted as the Sender’s relative power decreases.

Credible deviations from signaling equilibria

In games with costly signaling, some equilibria are vulnerable to deviations which could be “unambiguously” interpreted as coming from a unique set of Sender-types. This occurs when these types are precisely the ones who gain from deviating for any beliefs the Receiver could form over that set. We show that this idea characterizes a unique equilibrium outcome in two classes of games. First, in monotonic signaling games, only the Riley outcome is immune to this sort of deviation. Our result therefore provides a plausible story behind the selection made by Cho and Kreps’s (Q J Econ 102:179–221, 1987) D1 criterion on this class of games. Second, we examine a version of Crawford and Sobel (Econometrica 50:1431–1451, 1982) model with costly signaling, where standard refinements have no effect. We show that only a Riley-like separating equilibrium is immune to these deviations.

The Weak Sequential Core for Two-Period Economies

We adapt the classical core concept to deal with situations involving time and uncertainty. We define the weak sequential core as the set of allocations that are stable against coalitional deviations ex ante, and moreover cannot be improved upon by any coalition after the resolution of uncertainty. We restrict ourselves to credible deviations, where a coalitional deviation cannot be counterblocked by some subcoalition. We study the relationship of the resulting core concept with other sequential core concepts, give sufficient conditions under which the weak sequential core is non-empty, but show that it is possible to give reasonable examples where it is empty.

The Weak Sequential Core for Two-Period Economies

We adapt the core concept to deal with economies in which trade in assets takes place at period 1, uncertainty about asset payoffs is released at period 2, and agents trade in commodities afterwards. We define the weak sequential core as the set of allocations that are stable against coalitional deviations ex ante, and moreover cannot be improved upon by any coalition once the uncertainty is being released. We restrict ourselves to credible deviations, i.e. coalitional deviations at period 1 that cannot be counterblocked by some subcoalition at period 2. We study the relationship of the resulting core concept with other sequential core concepts, give sufficient conditions under which the weak sequential core is non-empty, but show that it is possible to give reasonable examples where it is empty.

Hydrogen Generation During Treatment of Simulated High-Level Radioactive Waste with Formic Acid

The Integrated Defense Waste Processing Facility (DWPF) Melter System (IDMS), operated by the Savannah River Technology Center, is a one-fifth scale pilot facility used in support of the startup and operation of the U.S. Department of Energy’s DWPF. Seven IDMS runs examined the effect of noble metals in simulated high-level radioactive waste (HLW) and important process variables on the generation of H2 during the preparation of melter feed with formic acid. The results showed that due to the noble metals in actual HLW, the lower flammable limit of H2 in air (4 vol%) could be exceeded in D WPF vessels, depending on such factors as off gas generation and air inleakage. A small but detectable quantity of H2 was generated even in the absence of noble metals. The results also verified that the most important process variable that affected the H2 generation rate was the amount of formic acid added to the system.Forced air purge systems with H2 monitoring instruments were installed in the DWPF to control the concentration of H2 in the offgas by fuel dilution during melter feed preparation. The design-basis forced air purge flow rate required in the DWPF during radioactive operations was based on the peak H2 generation rate observed during an IDMS run operated with 25% excess formic acid. This amount of excess formic acid was deemed a credible deviation from nominal operating conditions; therefore, a margin of safety was included in the design basis.

The phenol + formaldehyde runaway reaction. Vent sizing for reactor protection

Abstract The purpose of this paper is to demonstrate the use of the experimental techniques of the process safety laboratory to investigate the runaway reaction hazard of the phenol + formaldehyde reaction. A preliminary study of this reaction, using DTA and isothermal calorimetry helps in understanding the various aspects of the runaway reaction hazard and allows us to recognize the worst credible deviation leading to the most severe consequences. A vent is sized to protect the reactor from exploding due to this runaway reaction. The DIERS methodology is applied to determine the vent size: • characterization of the reaction behaviour • acquisition of the data necessary for vent sizing from adiabatic calorimetric techniques. The choice of the best calorimetric technique, to obtain experimental data for vent sizing, is discussed following the results of the various calorimetric methods. • taking into account the system behaviour and the experimental data obtained, a vent size is determined using various vent sizing equations and a relevant two phase flow model. This work demonstrates that a careful study is necessary to obtain reliable expeimental data for vent sizing. A single experiment could be misleading. This supports the conclusion that a good safety level is better achieved by the careful study of a limited number of dangerous reactions than by limited work on a great number of reactions.