Agent's Beliefs Research Articles

Shopper: A System for Executing and Simulating Expressive Plans

We present Shopper, a plan execution engine that facilitates experimental evaluation of plans and makes it easier for planning researchers to incorporate replanning. Shopper interprets the LTML plan language, which extends PDDL in two major ways: with more expressive control structures, and with support for semantic web services modeled on OWL-S. LTML's command structures include not only conventional ones such as branching, iteration, and procedure calls, but also features needed to handle HTN plans, such as precondition-filtered method choice. Unlike conventional programming languages, LTML supports interaction with the agent's belief store, so that its execution semantics line up with those assumed by planners. LTML actions extend PDDL actions in having outputs as well as effects, which means that they can support actions that sense the world; an important special case of this is semantic web services, which reveal information about a state hidden from the agent. To support experimentation as well as action in the real world, Shopper accommodates multiple, swappable implementations of its primitive action API. For example, one may interact with real web services through SOAP and WSDL, or with simulated web services through local procedure calls. We describe novel features of LTML, the interpretation strategy, swappable back-ends, and the implementation.

Belief base change as priority change: A study based on dynamic epistemic logic

AGM's belief revision is one of the main paradigms in the study of belief change operations. In this context, belief bases (prioritised bases) have been primarily used to specify the agent's belief state. While the connection of iterated AGM-like operations and their encoding in dynamic epistemic logics have been studied before, few works considered how well-known postulates from iterated belief revision theory can be characterised by means of belief bases. Particularly, it has been shown that some postulates can be characterised through transformations in priority graphs, while others may not be represented that way. This work investigates the expressive power of prioritized bases, employing priority graphs as a representation for an agent's belief state and of transformations on such bases as representations for iterated relational belief change operators. As such, we propose a new representation for an agent's belief state, which we show can be used to characterize different iterated belief change postulates not previously representable using transformations on priority graphs.

RL Generalization in a Theory of Mind Game Through a Sleep Metaphor (Student Abstract)

Training agents to learn efficiently in multi-agent environments can benefit from the explicit modelling of other agent's beliefs, especially in complex limited-information games such as the Hanabi card game. However, generalization is also highly relevant to performance in these games, though model comparisons at large training timescales can be difficult. In this work, we address this by introducing a novel model trained using a sleep metaphor on a reduced complexity version of the Hanabi game. This sleep metaphor consists an altered training regiment, as well as an information-theoretic constraint on the agent's policy. Results from experimentation demonstrate improved performance through this sleep-metaphor method, and provide a promising motivation for using similar techniques in more complex methods that incorporate explicit models of other agent's beliefs.

Can infants adopt underspecified contents into attributed beliefs? Representational prerequisites of theory of mind

Recent evidence suggests that young infants, as well as nonhuman apes, can anticipate others' behavior based on their false beliefs. While such behaviors have been proposed to be accounted by simple associations between agents, objects, and locations, human adults are undoubtedly endowed with sophisticated theory of mind abilities. For example, they can attribute mental contents about abstract or non-existing entities, or beliefs whose content is poorly specified. While such endeavors may be human specific, it is unclear whether the representational apparatus that allows for encoding such beliefs is present early in development. In four experiments we asked whether 15-month-old infants are able to attribute beliefs with underspecified content, update their content later, and maintain attributed beliefs that are unknown to be true or false. In Experiment 1, infants observed as an agent hid an object to an unspecified location. This location was later revealed in the absence or presence of the agent, and the object was then hidden again to an unspecified location. Then the infants could search for the object while the agent was away. Their search was biased to the revealed location (that could be represented as the potential content of the agent's belief when she had not witnessed the re-hiding), suggesting that they (1) first attributed an underspecified belief to the agent, (2) later updated the content of this belief, and (3) were primed by this content in their own action even though its validity was unknown. This priming effect was absent when the agent witnessed the re-hiding of the object, and thus her belief about the earlier location of the object did not have to be sustained. The same effect was observed when infants searched for a different toy (Experiment 2) or when an additional spatial transformation was introduced (Experiment 4), but not when the spatial transformation disrupted belief updating (Experiment 3). These data suggest that infants' representational apparatus is prepared to efficiently track other agents' beliefs online, encode underspecified beliefs and define their content later, possibly reflecting a crucial characteristic of mature theory of mind: using a metarepresentational format for ascribed beliefs.

Estimating robustness

I estimate and evaluate a model with a representative agent who is concerned that the persistence properties of her baseline model of consumption and inflation are misspecified. Coping with model uncertainty, she discovers a pessimistically biased worst-case model that dictates her behavior. I combine interest rates and aggregate macro series with cross-equation restrictions implied by robust control theory to estimate this worst-case distribution and show that (1) the model's predictions about key features of the yield curve are in line with the data, and (2) the degree of pessimism underlying these findings is plausible. Interpreting the worst-case as the agent's subjective belief, I derive model implied interest rate forecasts and compare them with analogous survey expectations. I find that the model can replicate the dynamics and average level of bias found in the survey.

Leverage and firm performance: new evidence on the role of economic sentiment using accounting information

PurposeThe goal of this paper is twofold. First, to examine the role of expectations in shaping agents' behaviour within an extended time frame which incorporates a prolonged harsh downturn of economic activity. Therefore, the authors allow for an indirect impact of economy-wide expectations operating via their coexistence with firms' balance sheet factors. Second, it is tested whether the behaviour of listed firms as regards to debt follows the pecking order theory.Design/methodology/approachThe authors use the panel data methodology in the estimation of the financial structure models since unobservable heterogeneity is an important determinant towards the target leverage. A fixed effects estimation procedure, with robust intercepts allowed to vary across firms, was employed to examine the relationship between leverage and performance.FindingsThe findings offer evidence of patterns of pecking order behaviour and thus for the necessity of internal financing over external debt. The authors also extended the set of determinants by investigating the effect of macroeconomic conditions on the debt decision of firms. Contrary to the authors’ expectations, short-run beliefs of economic agents appear to play a negative role in leverage.Originality/valueThis paper contributes to the literature in a number of ways. First, following the growing literature of loan dynamics, the findings provide useful insights into corporate capital structure decisions in an economy in which businesses were almost excluded from external financing for over a decade. Second, in order to better understand corporate financing decisions, it is necessary to consider the overall economic framework in which companies and especially the listed ones operate.

Monotonicity of equilibriums in Cournot competition with mixed interactions of agents and epistemic models of uncertain market

The paper continues the investigations of the sensitivity of the equilibriums for the Cournot competition with uncertain market capacity. There are two types of agents - stubborn and flexible, and two types of interactions - with and without communications. The main idea was based on a calculation of the sensitivity of the equilibriums to control. The equilibriums depend on beliefs of agents about market capacity and their beliefs about the beliefs of other agents. We have calculated the sensitivity of the equilibriums separately for each combination of types of agents. This paper focuses on a mixed case - when there are at least four clusters - each cluster for every combination of types of agents and their interactions.

Decision Making in Star Networks With Incorrect Beliefs

Consider a Bayesian binary decision-making problem in star networks, where local agents make selfish decisions independently, and a fusion agent makes a final decision based on aggregated decisions and its own private signal. In particular, we assume all agents have private beliefs for the true prior probability, based on which they perform Bayesian decision making. We focus on the Bayes risk of the fusion agent and counterintuitively find that incorrect beliefs could achieve a smaller risk than that when agents know the true prior. It is of independent interest for sociotechnical system design that the optimal beliefs of local agents resemble human probability reweighting models from cumulative prospect theory. We also consider asymptotic characterization of the optimal beliefs and fusion agent's risk in the number of local agents. We find that the optimal risk of the fusion agent converges to zero exponentially fast as the number of local agents grows. Furthermore, having an identical constant belief is asymptotically optimal in the sense of the risk exponent. For additive Gaussian noise, the optimal belief turns out to be a simple function of only error costs and the risk exponent can be explicitly characterized.

Belief Control Strategies for Interactions Over Weakly-Connected Graphs

In diffusion social learning over weakly-connected graphs, it has been shown recently that influential agents shape the beliefs of non-influential agents. This paper analyzes this mechanism more closely and addresses two main questions. First, the article examines how much freedom influential agents have in controlling the beliefs of the receiving agents, namely, whether receiving agents can be driven to arbitrary beliefs and whether the network structure limits the scope of control by the influential agents. Second, even if there is a limit to what influential agents can accomplish, this article develops mechanisms by which they can lead receiving agents to adopt certain beliefs. These questions raise interesting possibilities about belief control over networked agents. Once addressed, one ends up with design procedures that allow influential agents to drive other agents to endorse particular beliefs regardless of their local observations or convictions. The theoretical findings are illustrated by means of examples.

Robust Inference for Moment Condition Models without Rational Expectations

Applied researchers using structural models under rational expectations (RE) often confront empirical evidence of misspecification. In this paper we consider a generic dynamic model that is posed as a vector of unconditional moment restrictions. We suppose that the model is globally misspecified under RE, and thus empirically in a way that is not econometrically subtle. We relax the RE restriction by allowing subjective beliefs to differ from the data-generating probability (DGP) model while still maintaining that the moment conditions are satisfied under the subjective beliefs of economic agents. We use statistical measures of divergence relative to RE to bound the set of subjective probabilities. This form of misspecification alters econometric identification and inferences in a substantial way, leading us to construct robust confidence sets for various set identified functionals.

A Modified Supervaluationist Framework for Decision-Making

How strongly an agent beliefs in a proposition can be represented by her degree of belief in that proposition. According to the orthodox Bayesian picture, an agent's degree of belief is best represented by a single probability function. On an alternative account, an agent’s beliefs are modeled based on a set of probability functions, called imprecise probabilities. Recently, however, imprecise probabilities have come under attack. Adam Elga claims that there is no adequate account of the way they can be manifested in decision-making. In response to Elga, more elaborate accounts of the imprecise framework have been developed. One of them is based on supervaluationism, originally, a semantic approach to vague predicates. Still, Seamus Bradley shows that some of those accounts that solve Elga’s problem, have a more severe defect: they undermine a central motivation for introducing imprecise probabilities in the first place. In this paper, I modify the supervaluationist approach in such a way that it accounts for both Elga’s and Bradley’s challenges to the imprecise framework.

God's mind on morality.

Most research on cognition behind religious belief assumes that understanding of other minds is culturally uniform and follows the Western model of mind, which posits that (a) others' thoughts can be known and (b) action is best explained by mental state inference. This is potentially problematic if, as a growing body of evidence suggests, other populations view minds differently. We recruit Indigenous iTaukei Fijians who hold (a) a model of mind that discourages mental state inference and (b) co-existing Christian (Western) and traditional supernatural agent beliefs. Study 1 (N = 108), uses free-listing to examine how Western and local models of mind relate to beliefs. The Christian God cares about internal states and traits (aligning with the Western model of mind). Study 2 tests whether evoking God triggers intent focus in moral reasoning. Instead, God appears to enforce cultural models of mind in iTaukei (N = 151) and North Americans (N = 561). Expected divine judgement mirrors human judgement; iTaukei (N = 90) expect God to emphasise outcome, while Indo-Fijians (N = 219) and North Americans (N = 412) expect God to emphasise intent. When reminded to think about thoughts, iTaukei (N = 72) expect God to judge outcomes less harshly. Results suggest cultural/cognitive co-evolution: introduced cultural forms can spread new cognitive approaches, while Indigenous beliefs can persist as a reflection of local institutions.

EVALUATION OF AGONISTIC TENNIS IN GREECE: TENNIS PLAYERS' BELIEFS AND POSITION

Aim. Tennis popularity in Greece has been gaining ground in the last decade. The study examines the views of Greek tennis players about the sport. Materials and methods. The survey was conducted during the Hellenic Juniors' Tennis Tournament that took place in Athens, March 2019. Data were collected from a sample of 45 teenagers, participating at the Tournament. Survey participants completed a self-completion questionnaire. Data were analyzed with SPSS. Questions regarded the demographics and the teenagers' beliefs about the level of tennis in Greece, their preferences regarding tennis coaches, whether there are opportunities for tennis athletes to be promoted in Greece, the preferred characteristics of trainings and their view about organization of tennis in Greece. Results. The level of tennis in Greece is considered moderate to high. The quality of coaching is considered to be medium to high and coaches are expected to display many qualities and give at least once a month their feedback to the athletes. Tennis is an expensive sport that needs to be advertised by the media. The introduction of tennis in schools would augment the popularity of tennis in Greece. Conclusion. In order to have a broader view of tennis in Greece, it is important to take into consideration the beliefs of young tennis players, as well as the beliefs of tennis coaches and tennis agents.

Speculative bubbles under supply constraints, background risk and investment fraud in the art market

We examine the unexplored effects on art markets of artist death (asset supply constraints), collectors' wealth (background risk) and forgery risk (risk of investment fraud), under short-sale constraints and risk aversion. Speculative bubbles emerge and have the form of an option strangle (a put option and a call option), in which strike prices are affected by art supply constraints and the association of the artworks' emotional value with both collectors' wealth and forgery, while the options' underlying asset is the stochastic heterogeneous beliefs of agents. We show that speculative bubbles increase with four elements: art supply constraints; a more negative correlation between collectors' wealth and the artworks' emotional value; a more positive relationship between forgery and the artworks' emotional value; and more heterogeneous beliefs. These four sources of speculation increase the expected turnover rate; however, they also augment the variance of speculative bubbles, which generates price discounts (i.e. risk premiums) for holding artworks. Consequently, the net impact of speculation is not necessarily increased art prices. This study not only contributes to the art market literature, but also to studies about speculative bubbles in other financial markets under heterogeneous beliefs, short-sale constraints and risk-averse investors, since we additionally consider the simultaneous effect of asset supply constraints, investors' background risk and the risk of investment fraud.

General Bayesian theories and the emergence of the exclusivity principle

We address the problem of reconstructing quantum theory from the perspective of an agent who makes bets about the outcomes of possible experiments. We build a general Bayesian framework that can be used to organize the agent's beliefs and update them when new information becomes available. Our framework includes as special cases classical and quantum probability theory, as well as other forms of probabilistic reasoning that may arise in future physical theories. Building on this framework, we develop a notion of ideal experiment, which in quantum theory coincides with the notion of projective measurement. We then prove that, in every general Bayesian theory, ideal experiments must satisfy the exclusivity principle, a property of projective measurements that plays a central role in the characterization of quantum correlations. Our result suggests that the set of quantum correlations may be completely characterized in terms of Bayesian consistency conditions.

Narrative Planning for Belief and Intention Recognition

Planning algorithms generate sequences of actions that achieve a goal, but they can also be used in reverse: to infer the goals that led to a sequence of actions. Traditional plan-based goal recognition assumes agents are rational and the environment is fully observable. Recent narrative planning models represent agents as believable rather than perfectly rational, meaning their actions need to be justified by their goals, but they may act in ways that are not optimal, and they may possess incorrect beliefs about the environment. In this work we propose a technique for inferring the goals and beliefs of agents in this context, where rationality and omniscience are not assumed. We present two evaluations that investigate the effectiveness of this approach. The first uses partial observation sequences and shows how this impacts the algorithm’s accuracy. The second uses human data and compares the algorithm’s inferences to those made by humans.

Robust virtual implementation with almost complete information

Artemov, Kunimoto, and Serrano (2013a,b, henceforth, AKS) study a mechanism design problem where arbitrary restrictions are placed on the set of first-order beliefs of agents. Calling these restrictions Δ, they adopt Δ-rationalizability (Battigalli and Siniscalchi, 2003) and show that Δ-incentivecompatibility and Δ-measurability are necessary and sufficient conditions for robust virtual implementation, which implies that virtual implementation is possible uniformly over all type spaces consistent with Δ-restrictions. By appropriately defining Δ in order to restrict attention to complete information environments and thereafter explicitly modelling the assumption of complete information in the language of type spaces, I re-establish the permissive implementation result of Abreu and Matsushima (1992a). However, AKS need to fix a complete information environment throughout their analysis and therefore does not enable us to ask if robust virtual implementation results are “robust” to the relaxation of the complete information environment. The main result of this paper shows that permissive robust virtual implementation results can be extended to nearby incomplete information environments. I also obtain a tight connection between the class of nearby incomplete information environments considered by this paper and that considered by Oury and Tercieux (2012).

The transmission of academic values between best friends: How important is an accurate perception?

IntroductionBased on the expectancy-value theory and value transmission theory, the present study investigated the transmission process of academic values between best friends within the classroom. Expectancy-value theory argues that value related beliefs of important socialization agents influence the development of adolescents' academic values and that this effect is mediated through adolescents' perception of socializers' academic values. In this regard, best friends within the classroom were less focused by researchers although they become important socialization agents in adolescence. Therefore, the present study investigated the influence of friends' actual academic values on adolescents' academic values, and if this effect is mediated through adolescents' perception of friends’ actual values. All dimensions of academic values according to the expectancy-value theory were focused: intrinsic value, attainment value, utility value, and emotional cost. MethodsThe research questions were investigated based on a two-wave longitudinal study in Germany. The final sample comprised of 303 adolescents of the fifth and seventh grade with a stable, reciprocated friend. ResultsStructural equation models revealed that the friends' actual attainment value indirectly influenced the attainment value of adolescents through the friends’ perceived attainment value. The same effect pattern was found for emotional cost. For the utility value and intrinsic value, no transmission effect was observed. ConclusionThe results provide evidence that the transmission process was not uniform for all of the academic values. Results were discussed in terms of different theoretical concepts explaining the value transmission process between friends.

Reflexion Processes and Equilibrium in an Oligopoly Model with a Leader

An oligopoly model with a leader in the class of linear demand and cost functions of agents is considered, and the dynamic processes of reflexive behavior in this model are analytically studied. Dynamic decision-making processes with the inaccurate beliefs of agents about the choice of competitors are implemented not through the optimal responses to their expected actions, but as repeated static games on a range of admissible responses. Such an approach to decision-making is demonstrated to be justified. Observing the current state of the market and considering current economic restrictions (competitiveness and profit), agents refine their outputs in game-to-game dynamics and take steps towards the current position of their goal. A Stackelberg leader and other agents with the Cournot response choose step sizes independently of each other. Sufficient conditions on the step sizes under which the dynamics converge to an equilibrium are established.

Six Types of Ambiguity in a Ramsey Climate Policy Model

While the scientific community is in general agreement about the nature and threat of global warming, the public and many political leaders are not. This paper casts the lack of full agreement as an instance of belief heterogeneity giving rise to six potential types of ambiguity with differing implications for carbon taxation and fiscal policy. Treating the Ramsey planner as a Stackelberg leader and private agents as followers, I distinguish three types of policy regime: (i) a political regime that strategically adopts the private sector's beliefs, (ii) a paternalistic regime that trust its own model only, and (iii) a pessimistic government with its own doubts about the climate model. The beliefs of private agents are represented by martingale multiplier perturbations M to a common approximating probability function and may be of two kinds: for pessimists}, M is a device to construct robust Euler conditions; for optimists, M is arbitrary and unknown to the planner, hence a source of ambiguity. The six proposed types of ambiguity differ in what the planner is ambiguous about, what private agents and the government know, and what the government believes private beliefs to be. In all instances, ambiguity induces robustness in policy and/or private decision rules affecting the social cost of carbon, and carbon and capital taxation. This paper shows further that, crucially, the carbon tax is not independent of other elements in fiscal policy. The results are framed in terms of distorted Arrow-Debreu pricing theory to show that the optimal carbon tax is equivalent to the permit price of an underlying asset---the government-imposed limit on emissions in economies with cap and trade.