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Bita Banihashemi

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9 papers
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9

AIJ Journal 2025 Journal Article

Abstracting situation calculus action theories

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lespérance

We develop a general framework for agent abstraction based on the situation calculus and the ConGolog agent programming language. We assume that we have a high-level specification and a low-level specification of the agent, both represented as basic action theories. A refinement mapping specifies how each high-level action is implemented by a low-level ConGolog program and how each high-level fluent can be translated into a low-level formula. We define a notion of sound abstraction between such action theories in terms of the existence of a suitable bisimulation between their respective models. Sound abstractions have many useful properties that ensure that we can reason about the agent's actions (e. g. , executability, projection, and planning) at the abstract level, and refine and concretely execute them at the low level. We also characterize the notion of complete abstraction where all actions (including exogenous ones) that the high level thinks can happen can in fact occur at the low level. To facilitate verifying that one has a sound/complete abstraction relative to a mapping, we provide a set of necessary and sufficient conditions. Finally, we identify a set of basic action theory constraints that ensure that for any low-level action sequence, there is a unique high-level action sequence that it refines. This allows us to track/monitor what the low-level agent is doing and describe it in abstract terms (i. e. , provide high-level explanations, for instance, to a client or manager).

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IJCAI Conference 2023 Conference Paper

Abstraction of Nondeterministic Situation Calculus Action Theories

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lesperance

We develop a general framework for abstracting the behavior of an agent that operates in a nondeterministic domain, i. e. , where the agent does not control the outcome of the nondeterministic actions, based on the nondeterministic situation calculus and the ConGolog programming language. We assume that we have both an abstract and a concrete nondeterministic basic action theory, and a refinement mapping which specifies how abstract actions, decomposed into agent actions and environment reactions, are implemented by concrete ConGolog programs. This new setting supports strategic reasoning and strategy synthesis, by allowing us to quantify separately on agent actions and environment reactions. We show that if the agent has a (strong FOND) plan/strategy to achieve a goal/complete a task at the abstract level, and it can always execute the nondeterministic abstract actions to completion at the concrete level, then there exist a refinement of it that is a (strong FOND) plan/strategy to achieve the refinement of the goal/task at the concrete level.

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AAAI Conference 2022 Conference Paper

From Actions to Programs as Abstract Actual Causes

  • Bita Banihashemi
  • Shakil M. Khan
  • Mikhail Soutchanski

Causality plays a central role in reasoning about observations. In many cases, it might be useful to define the conditions under which a non-deterministic program can be called an actual cause of an effect in a setting where a sequence of programs are executed one after another. There can be two perspectives, one where at least one execution of the program leads to the effect, and another where all executions do so. The former captures a “weak” notion of causation and is more general than the latter stronger notion. In this paper, we give a definition of weak potential causes. Our analysis is performed within the situation calculus basic action theories and we consider programs formulated in the logic programming language ConGolog. Within this setting, we show how one can utilize a recently developed abstraction framework to relate causes at various levels of abstraction, which facilitates reasoning about programs as causes.

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IJCAI Conference 2018 Conference Paper

Abstraction of Agents Executing Online and their Abilities in the Situation Calculus

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lespérance

We develop a general framework for abstracting online behavior of an agent that may acquire new knowledge during execution (e. g. , by sensing), in the situation calculus and ConGolog. We assume that we have both a high-level action theory and a low-level one that represent the agent's behavior at different levels of detail. In this setting, we define ability to perform a task/achieve a goal, and then show that under some reasonable assumptions, if the agent has a strategy by which she is able to achieve a goal at the high level, then we can refine it into a low-level strategy to do so.

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AAMAS Conference 2018 Conference Paper

Hierarchical Agent Supervision

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lesp�rance

Agent supervision is a form of control/customization where a supervisor restricts the behavior of an agent to enforce certain requirements, while leaving the agent as much autonomy as possible. To facilitate supervision, it is often of interest to consider hierarchical models where a high level abstracts over low-level behavior details. We study hierarchical agent supervision in the context of the situation calculus and the ConGolog agent programming language, where we have a rich first-order representation of the agent state. We define the constraints that ensure that the controllability of individual actions at the high level in fact captures the controllability of their implementation at the low level. On the basis of this, we show that we can obtain the maximally permissive supervisor by first considering only the high-level model and obtaining a highlevel supervisor and then refining its actions locally, thus greatly simplifying the supervisor synthesis task.

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AAAI Conference 2017 Conference Paper

Abstraction in Situation Calculus Action Theories

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lesperance

We develop a general framework for agent abstraction based on the situation calculus and the ConGolog agent programming language. We assume that we have a high-level specification and a low-level specification of the agent, both represented as basic action theories. A refinement mapping specifies how each high-level action is implemented by a lowlevel ConGolog program and how each high-level fluent can be translated into a low-level formula. We define a notion of sound abstraction between such action theories in terms of the existence of a suitable bisimulation between their respective models. Sound abstractions have many useful properties that ensure that we can reason about the agent’s actions (e. g. , executability, projection, and planning) at the abstract level, and refine and concretely execute them at the low level. We also characterize the notion of complete abstraction where all actions (including exogenous ones) that the high level thinks can happen can in fact occur at the low level.

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IJCAI Conference 2016 Conference Paper

Online Agent Supervision in the Situation Calculus

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lesp
  • eacute; rance

Agent supervision is a form of control / customization where a supervisor restricts the behavior of an agent to enforce certain requirements, while leaving the agent as much autonomy as possible. In this work, we investigate supervision of an agent that may acquire new knowledge about her environment during execution, for example, by sensing. Thus we consider an agent's online executions, where, as she executes the program, at each time point she must make decisions on what to do next based on what her current knowledge is. This is done in a setting based on the situation calculus and a variant of the ConGolog programming language. The main results of this paper are (i) a formalization of the online maximally permissive supervisor, (ii) a sound and complete technique for execution of the agent as constrained by such a supervisor, and (iii)a new type of lookahead search construct that ensures nonblockingness over such online executions.

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KR Conference 2016 Short Paper

Online Situation-Determined Agents and their Supervision

  • Bita Banihashemi
  • Giuseppe De Giacomo
  • Yves Lesperance

Agent supervision is a form of control/customization where a supervisor restricts the behavior of an agent to enforce certain requirements, while leaving the agent as much autonomy as possible. In this work, we investigate supervision of an agent that may acquire new knowledge about her environment during execution, for example, by sensing. Thus we consider an agent’s online executions, where, as she executes the program, at each time point she must make decisions on what to do next based on what her current knowledge is. This is done in a setting based on the situation calculus and a variant of the ConGolog programming language. To reason about such agents, we first define a notion of online situation-determined agent which ensures that for any sequence of actions that the agent can perform online, the resulting agent configuration is unique. We then present our formalization of the online maximally permissive supervisor.

KER Journal 2011 Journal Article

Representing and classifying arguments on the Semantic Web

  • Iyad Rahwan
  • Bita Banihashemi
  • Chris Reed
  • Douglas Walton
  • Sherief Abdallah

Abstract Until recently, little work has been dedicated to the representation and interchange of informal, semi-structured arguments of the type found in natural language prose and dialogue. To redress this, the research community recently initiated work towards an Argument Interchange Format (AIF). The AIF aims to facilitate the exchange of semi-structured arguments among different argument analysis and argumentation-support tools. In this paper, we present a Description Logic ontology for annotating arguments, based on a new reification of the AIF and founded in Walton's theory of argumentation schemes. We demonstrate how this ontology enables a new kind of automated reasoning over argument structures, which complements classical reasoning about argument acceptability. In particular, Web Ontology Language reasoning enables significantly enhanced querying of arguments through automatic scheme classifications, instance classification, inference of indirect support in chained argument structures, and inference of critical questions. We present the implementation of a pilot Web-based system for authoring and querying argument structures using the proposed ontology.

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