On the emergent Semantic Web and overlooked issues

The emergent Semantic Web, despite being in its infancy, has already received a lotof attention from academia and industry. This resulted in an abundance of prototype systems and discussion most of which are centred around the underlying infrastructure. However, when we critically review the work done to date we realise that there is little discussion with respect to the vision of the Semantic Web. In particular, there is an observed dearth of discussion on how to deliver knowledge sharing in an environment such as the Semantic Web in effective and efficient manners. There are a lot of overlooked issues, associated with agents and trust to hidden assumptions made with respect to knowledge representation and robust reasoning in a distributed environment. These issues could potentially hinder further development if not considered at the early stages of designing Semantic Web systems. In this perspectives paper, we aim to help engineers and practitioners of the Semantic Web by raising awareness of these issues

Dynamic Logic of Common Knowledge in a Proof Assistant

Common Knowledge Logic is meant to describe situations of the real world where a group of agents is involved. These agents share knowledge and make strong statements on the knowledge of the other agents (the so called \emph{common knowledge}). But as we know, the real world changes and overall information on what is known about the world changes as well. The changes are described by dynamic logic. To describe knowledge changes, dynamic logic should be combined with logic of common knowledge. In this paper we describe experiments which we have made about the integration in a unique framework of common knowledge logic and dynamic logic in the proof assistant \Coq. This results in a set of fully checked proofs for readable statements. We describe the framework and how a proof can beComment: 15

Reasoning about Social Relationships with Jason

Abstract. This work faces the problem of enabling an approach to agent programming, which allows agents to seamlessly manage and work both on social relationships and on abstractions which typically characterize agents themselves, like goals, beliefs, intentions. A similar approach is necessary in order to easily develop Socio-Technical Systems and provides a basis for carrying on methodological studies on system engineering. The paper presents an extension of JaCa(Mo) in which Jason agents can reason on social relationships, that are represented as commitments, and where Jason agents interact by way of special CArtAgO artifacts, which reify commitment-based protocols

Relation-changing modal operators

We study dynamic modal operators that can change the accessibility relation of a model during the evaluation of a formula. In particular, we extend the basic modal language with modalities that are able to delete, add or swap an edge between pairs of elements of the domain. We define a generic framework to characterize this kind of operations. First, we investigate relation-changing modal logics as fragments of classical logics. Then, we use the new framework to get a suitable notion of bisimulation for the logics introduced, and we investigate their expressive power. Finally, we show that the complexity of the model checking problem for the particular operators introduced is PSpace-complete, and we study two subproblems of model checking: formula complexity and program complexity.Fil: Areces, Carlos Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fervari, Raul Alberto. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hoffmann, Guillaume Emmanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Dynamic agent safety logic : theory and applications

Modal logic is a family of logics for reasoning about relational structures, broadly construed. It sits at the nexus of philosophy, mathematics, software engineering, and economics. By modeling a target domain as a relational structure, one can define a modal logic for reasoning about its properties. Common examples include modal logics for knowledge, belief, time, program execution, mathematical provability, and ethics. This thesis presents a modal logic that combines several modalities in order to reason about realistic human-like agents. We combine knowledge, belief, action, and safe action, which we call Dynamic Agent Safety Logic, or DASL. We distinguish DASL from other modal logics treating similar topics by arguing that the standard models of human agency are not adequate. We present some criteria a logic of agency should strive to achieve, and then compare how related logics fare. We use the Coq interactive theorem prover to mechanically prove soundness and completeness results for the logic, as well as apply it to case studies in the domain of aviation safety, demonstrating its ability to model realistic, minimally rational agents. Finally, we examine the consequences of modeling agents capable of a certain sort of self-reflection. Such agents face a formal difficulty due to Lob's Theorem, called Lob's Obstacle in the literature. We show how DASL can be relaxed to avoid Lob's Obstacle, while the other modal logics of agency cannot easily do so.Includes bibliographical reference

Why Philosophers Should Care About Computational Complexity

One might think that, once we know something is computable, how efficiently it can be computed is a practical question with little further philosophical importance. In this essay, I offer a detailed case that one would be wrong. In particular, I argue that computational complexity theory---the field that studies the resources (such as time, space, and randomness) needed to solve computational problems---leads to new perspectives on the nature of mathematical knowledge, the strong AI debate, computationalism, the problem of logical omniscience, Hume's problem of induction, Goodman's grue riddle, the foundations of quantum mechanics, economic rationality, closed timelike curves, and several other topics of philosophical interest. I end by discussing aspects of complexity theory itself that could benefit from philosophical analysis.Comment: 58 pages, to appear in "Computability: G\"odel, Turing, Church, and beyond," MIT Press, 2012. Some minor clarifications and corrections; new references adde

The Philosophy of Science Fiction: Henri Bergson and the Fabulations of Philip K. Dick

The Philosophy of Science Fiction: Henri Bergson and the Fabulations of Philip K. Dick explores the deep affinity between two seemingly quite different thinkers, in their attempts to address the need for salvation in (and from) an era of accelerated mechanization, in which humans' capacity for destroying or subjugating the living has attained a planetary scale. The philosopher and the science fiction writer come together to meet the contradictory imperatives of a realist outlook-a task which, arguably, philosophy and science fiction could only ever adequately undertake in collaboration. Their respective approaches meet in a focus on the ambiguous status of fictionalizing, or fabulation, as simultaneously one of mechanization's most devastating tools, and the possibility of its undoing. When they are read together, the complexities and paradoxes thrown up by this ambiguity, with which both Bergson and Dick struggle on their own, open up new ways to navigate ideas of mechanism and mysticism, immanence and transcendence, and the possibility and meaning of salvation. The result is at once an original reading of both thinkers, a new critical theory of the socio–cultural, political and ethical function of fictionalizing, and a case study in the strange affinity, at times the uncanny similarity, between philosophy and science fiction

Description logics of context

We introduce Description Logics of Context (DLCs)—an extension of Description Logics (DLs) for context-based reasoning. Our approach descends from J. McCarthy's tradition of treating contexts as formal objects over which one can quantify and express first-order properties. DLCs are founded in two-dimensional possible world semantics, where one dimension represents a usual object domain and the other a domain of contexts, and accommodate two interacting DL languages—the object and the context language—interpreted over their respective domains. Effectively, DLCs comprise a family of two-sorted , two-dimensional combinations of pairs of DLs. We argue that this setup ensures a well-grounded, generic framework for capturing and studying mechanisms of contextualization in the DL paradigm. As the main technical contribution, we prove 2ExpTime-completeness of the satisfiability problem in the maximally expressive DLC, based on the DL forumla . As an interesting corollary, we show that under certain conditions this result holds also for a range of two-dimensional DLs, including the prominent forumla