Logic Of Awareness Research Articles

Policy-based Awareness Management (PAM): Case study of a wireless communication system at a hospital

The present paper evaluates the use of software agents to identify relevance of information, called awareness. This evaluation is based on existing policies and scenarios in the context of wireless communication of a hospital in Norway. The study is to address the lack of literature for experimental studies on a method to employ software agents for awareness identification. Research in computer supported cooperative work indicates the significant contributions of software agents to assist individuals. There are bodies of work that show awareness provides the means for software agents in which effective cooperation can take place. In addition, the role of the methods to identify awareness is emphasized in the literature of both computer supported cooperative work and software agents. This paper explains a step-wise process, called Policy-based Awareness Management, which allows agents to use policies as a source to identify awareness and thus change their behaviors accordingly. The contribution of this method is based on the concepts proposed by the logic of general awareness. The present study applies Directory Enabled Networks-next generation as the policy structure for the method. The paper evaluates the process via its application to identify the relevance of information in wireless communication scenarios in a hospital. The present study conducts observations, interviews and discussions on the wireless communication system of the hospital to identify the different scenarios happening in the system. The paper presents a set of simulations on these scenarios and concludes that the method is effective and cost-efficient.

Equivalence of the Information Structure with Unawareness to the Logic of Awareness

This paper proves Li (2009) unawareness structure equivalent to the single-agent propositionally generated logic of awareness of Fagin and Halpern (1988). For any model of one type one can construct a model of the other type describing the same belief and awareness. Li starts from an agent unable to perceive aspects of the world and distinguish states, modeled with subjective state spaces coarser than the objective state space. Fagin and Halpern limit the agent’s language or cognitive ability to reasoning only about a subset of the propositions describing the world. Equivalence of these approaches suggests they capture a natural notion of unawareness in a minimal way.

Reasoning about knowledge of unawareness

Awareness has been shown to be a useful addition to standard epistemic logic. However, standard propositional logics for knowledge and awareness cannot express the fact that an agent knows that there are facts of which he is unaware without there being an explicit fact that the agent knows he is unaware of. We extend Fagin and Halpern's logic of general awareness to a logic that allows quantification over variables, so that there is a formula in the language that says “an agent explicitly knows that there exists a fact of which he is unaware.” Moreover, that formula can be true without the agent explicitly knowing that he is unaware of any particular formula. We provide a sound and complete axiomatization of the logic. Finally, we show that the validity problem for the logic is recursively enumerable, but not decidable.

QUANTIFIED LOGIC OF AWARENESS AND IMPOSSIBLE POSSIBLE WORLDS

Among the many possible approaches to dealing with logical omniscience, I consider here awareness and impossible worlds structures. The former approach, pioneered by Fagin and Halpern, distinguishes between implicit and explicit knowledge, and avoids logical omniscience with respect to explicit knowledge. The latter, developed by Rantala and by Hintikka, allows for the existence of logically impossible worlds to which the agents are taken to have “epistemological” access; since such worlds need not behave consistently, the agents’ knowledge is fallible relative to logical omniscience. The two approaches are known to be equally expressive in propositional systems interpreted over Kripke semantics. In this paper I show that the two approaches are equally expressive in propositional systems interpreted over Montague-Scott (neighborhood) semantics. Furthermore, I provide predicate systems of both awareness and impossible worlds structures interpreted on neighborhood semantics and prove the two systems to be equally expressive.

Two-Dimensional Awareness Logics

Awareness logic is a type of belief logic in which an agent's beliefs are restricted to those sentences that the agent is aware of. Awareness logic is a successful way to circumvent the problem of omniscience so that actual belief is modelled in a reasonable way. In this paper, we suggest a new method modelling awareness and actual belief by using two-dimensional logics. We show that the two-dimensional logics are flexible tools. Different types of concepts of awareness can be easily modelled by this method.

Towards an Awareness-Based Semantics for Security Protocol Analysis

We report on work-in-progress on a new semantics for analyzing security protocols that combines complementary features of security logics and inductive methods. We use awareness to model the agents' resource-bounded reasoning and, in doing so, capture a more appropriate notion of belief than those usually considered in security logics. We also address the problem of modeling interleaved protocol executions, adapting ideas from inductive methods for protocol verification. The result is an intuitive, but expressive, doxastic logic for formalizing and reasoning about attacks. As a case study, we use awareness to characterize, and demonstrate the existence of, a man-in-the-middle attack upon the Needham-Schroeder Public Key protocol. This is, to our knowledge, not only the first doxastic analysis of this attack but also the first practical application of an awareness logic. Even though defining the awareness sets of the agents, a task that is left unspecified in formal works on awareness logics, turns out to be surprisingly subtle, initial results suggest that our approach is promising for modeling, verifying and reasoning about security protocols and their properties.

Epistemic logic and logical omniscience II: A unifying framework

In a published paper entitled Epistemic Logic and Logical Omniscience: A Survey (Int J Intell Syst 1997, 12, 57–81) a collection of epistemic logics were reviewed and critiqued. This sequel paper provides evidence for the claim that a unifying framework for various existing epistemic logics can be defined. Of particular interest is the logic of implicit and explicit belief, the logic of awareness, and the Cadoli–Schaerf epistemic model. Although these logics appear to have surface dissimilarities, a closer examination shows that they have a strong resemblance. The contribution of this paper is to show that a unifying framework MEL (multi-valued epistemic logic) that integrates the features of these three logics can be defined. In this paper, it is proven that the semantics of MEL subsumes the semantics of the logic of implicit and explicit belief, the logic of awareness, and the Cadoli–Schaerf epistemic model. By placing some constraints on MEL, various epistemic notions such as implicit belief, explicit belief, and awareness can be modeled. ©2000 John Wiley & Sons, Inc.

Epistemic logic and logical omniscience II: A unifying framework

In a published paper entitled Epistemic Logic and Logical Omniscience: A Survey (Int J Intell Syst 1997, 12, 57–81) a collection of epistemic logics were reviewed and critiqued. This sequel paper provides evidence for the claim that a unifying framework for various existing epistemic logics can be defined. Of particular interest is the logic of implicit and explicit belief, the logic of awareness, and the Cadoli–Schaerf epistemic model. Although these logics appear to have surface dissimilarities, a closer examination shows that they have a strong resemblance. The contribution of this paper is to show that a unifying framework MEL (multi-valued epistemic logic) that integrates the features of these three logics can be defined. In this paper, it is proven that the semantics of MEL subsumes the semantics of the logic of implicit and explicit belief, the logic of awareness, and the Cadoli–Schaerf epistemic model. By placing some constraints on MEL, various epistemic notions such as implicit belief, explicit belief, and awareness can be modeled. ©2000 John Wiley & Sons, Inc.

Reasoning tractably about explicit belief: A model-theoretic approach

Existing epistemic logics such as the logic of implicit and explicit belief and the logic of awareness adopt a deductive-theoretic approach for characterizing belief. In this approach, an agent represents the state of the world with a conjunction of axioms in its knowledge base (KB) and evaluates queries by trying to prove or disprove that they follow from KB. This paper presents a multivalued epistemic logic (MEL) that allows agents to reason both deductively and model theoretically about implicit and explicit belief. By characterizing an agent's KB with a class of finite models, the set of formulas that an agent believes can be determined by checking their validity in all these models. This rests on the fact that MEL has a complete axiomatization (sentences that are true in all these models will also be provable). In this paper, the soundness, completeness, and decidability of MEL are proven. Furthermore, a polynomial time model-checking algorithm for determining the satisfiability of a sentence at a particular state in a given model of MEL is also presented. © 2000 John Wiley & Sons, Inc.

Epistemic logic and logical omniscience: A survey

This survey brings together a collection of epistemic logics and discusses their approaches in alleviating the logical omniscience problem. Of particular note is the logic of implicit and explicit belief. Explicit belief refers to information actively held by an agent, while implicit belief refers to the logical consequence of explicit belief. Ramifications of Levesque's logic include nonstandard epistemic logic and the logics of awareness and local reasoning. Models of nonstandard epistemic logic are defined with respect to nonstandard proportional logic to weaken its semantics. In the logic of awareness, an agent can only believe a concept that it is aware of. Closely related to awareness are S-1 and S-3 epistemic operators which can be used to model skeptical and credulous agents. The logic of local reasoning provides a semantics for representing the fact that agents can have different clusters of beliefs which may contradict each other. Other variations include epistemic structures which are generalizations of the logic of local reasoning and fusion epistemic models which provide an account that agents can combine information conjunctively or disjunctively. Another closely related approach is the logic of explicit propostions which captures the insight that agents can hold beliefs independently without putting them together. © 1997 John Wiley & Sons, Inc.

Epistemic logic and logical omniscience: A survey

This survey brings together a collection of epistemic logics and discusses their approaches in alleviating the logical omniscience problem. Of particular note is the logic of implicit and explicit belief. Explicit belief refers to information actively held by an agent, while implicit belief refers to the logical consequence of explicit belief. Ramifications of Levesque's logic include nonstandard epistemic logic and the logics of awareness and local reasoning. Models of nonstandard epistemic logic are defined with respect to nonstandard proportional logic to weaken its semantics. In the logic of awareness, an agent can only believe a concept that it is aware of. Closely related to awareness are S-1 and S-3 epistemic operators which can be used to model skeptical and credulous agents. The logic of local reasoning provides a semantics for representing the fact that agents can have different clusters of beliefs which may contradict each other. Other variations include epistemic structures which are generalizations of the logic of local reasoning and fusion epistemic models which provide an account that agents can combine information conjunctively or disjunctively. Another closely related approach is the logic of explicit propostions which captures the insight that agents can hold beliefs independently without putting them together. © 1997 John Wiley & Sons, Inc.

A fugue on the themes of awareness logic and correspondence

ABSTRACT We consider certain objections against Fagin's and Halpern's logic of general awareness and interpret them as doubts whether there exists a correspondence theory for awareness logic with respect to sieve models. We present a non-compositional translation from epistemic formulas into first-order logic as the essential ingredient of such a correspondence theory and define a suitable notion of bisimulation. Moreover, in order to further underline the power of sieve models, we prove the Lewis system SI to be complete for a relational interpretation which is equivalent to the sieve model semantics.