Abstract. A conceptual graph (CG) is a graph representation for logic based on the semantic networks of artificial intelligence and the existential graphs of Charles Sanders Peirce. Several versions of CGs have been designed and implemented over the past thirty years. The simplest are the typeless core CGs, which correspond to Peirce’s original existential graphs. More common are the extended CGs, which are a typed superset of the core. The research CGs have explored novel techniques for reasoning, knowledge representation, and natural language semantics. The semantics of the core and extended CGs is defined by a formal mapping to and from the draft ISO standard for Common Logic, but the research CGs are defined by a variety of formal and informal extensions. This article surveys the notation, applications, and reasoning methods used with CGs and their mapping to and from other versions of logic. This is a preprint of Chapter 5 of the Handbook of Knowledge Representation, ed. by F. van Harmelen,

In this review of metaprogramming in logic we pay equal attention to theoretical and practical issues: the contents range from mathematical and logical preliminaries to implementation and applications in, e.g., software engineering and knowledge representation. The area is one in rapid development but we have emphasized such issues that are likely to be important for future metaprogramming languages and methodologies. 1 Introduction The term `metaprogramming' relates to `programming' as `metalanguage' relates to `language' and `metalogic' to `logic': programming where the data represent programs. It should be no surprise that metaprogramming with logic programming languages takes advantage of many results from metalogic. In the most general interpretation we would say that `metaprogramming ' refers to any kind of computer programming where the input or output represents programs. We will refer to a program of this kind as a metaprogram and to its data as object programs. Analogousl...

This paper presents a theory expressed in first-order logic for describing and supporting inference about action, knowledge, planning, and communication, in an egalitarian multi-agent setting. The underlying ontology of the theory uses a situation-based temporal model and a possible-worlds model of knowledge. It supports plans and communications of a very general kind, both informative communications and requests. Communications may refer to states of the world or states of knowledge in the past, present, or future. We demonstrate that the theory is powerful enough to represent several interesting multi-agent planning problems and to justify their solutions. We have proven that the theory of knowledge, communication, and planning is consistent with a broad range of physical theories, despite the existence of a number of potential paradoxes.

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Syntactical treatments of propositional attitudes are attractive to artificial intelligence researchers. But results of Montague [12] and Thomason [16] seem to show that syntactical treatments are not viable. They show that if representation languages are sufficiently expressive, then axiom schemes characterizing knowledge and belief give rise to paradox. De Rivi`eres and Levesque [6] characterized a class of sentences within which these schemes can safely be instantiated. These sentences do not quantify over the propositional objects of knowledge and belief. We argue that their solution is incomplete, and extend it by characterizing a more inclusive class of sentences over which the axiom schemes can safely range. Our sentences do quantify over propositional objects. 1 Syntactical treatments of the attitudes Knowledge, belief, desire, intention and other propositional attitudes have propositional objects. Concerning the nature of these objects there seem to be two main possibilities....

Modeling is one of the most fundamental processes of the human mind. Yet it is often misunderstood in ways that seriously limit our ability to function coherently and effectively in the world. The use of inappropriate models (or the inappropriate use of modeling itself) is

We introduce the concept of reflection principle as a knowledge representation paradigm in a computational logic setting. Reflection principles are expressed as certain kinds of logic schemata intended to capture the basic properties of the domain knowledge to be modeled. Reflection is then used to instantiate these schemata to answer specific queries about the domain. This differs from other approaches to reflection mainly in the following three ways. First, it uses logical instead of procedural reflection. Second, it aims at a cognitively adequate declarative representation of various forms of knowledge and reasoning, as opposed to reflection as a means for controlling computation or deduction. Third, it facilitates the building of a complex theory by allowing a simpler theory to be enhanced by a compact metatheory, contrary to the construction of metatheories that are only conservative extensions of the basic theory. A computational logic system for embedding reflection principles, called RCL (for Reflective Computational Logic), is presented in full detail. The system is an extension of Horn clause resolution-based logic, and is devised in a way that makes important features of reflection parametric as much as possible, so that they can be tailored according to specific needs of different application domains. Declarative and procedural semantics of the logic are described and correctness and completeness of reflection as logical 1 inference are proved. Examples of reflection principles for three different application areas are shown. Relationship with a variety of distinct sources within the literature on relevant topics is discussed.

This book is about the interface between natural language and the sensorimotor system. It is obvious that there is an interface between language and sensorimotor cognition, because we can talk about what we see and do. The main proposal in the book is that the interface is more direct than is commonly assumed. To argue for this proposal I focus on a simple concrete episode—a man grabbing a cup—which can be reported in a simple transitive sentence (e.g. the English sentence The man grabbed a cup). In the first part of the book I present a detailed model of the sensorimotor processes involved in experiencing this episode, both as the agent bringing it about and as an observer watching it happen. The model draws on a large body of research in neuroscience and psychology. I also present a model of the syntactic structure of the associated transitive sentence, developed within the entirely separate discipline of theoretical linguistics. This latter model is a version of Chomsky’s ‘Minimalist ’ syntactic theory, which assumes that a sentence reporting the episode has the same underlying syntactic structure (called ‘logical form’) regardless of which language it is in. My main proposal is that these two independently motivated models are in fact closely

The aim of this thesis is the development of a minimal semantic ontology merging intuitions from Strawson's theory of individuals and Parsons' theory of events and thematic roles. This ontology as a set of top-level conceptual distinctions is shown to be the foundation for the semantic subcategorisation of verbs and the basic logical structure of natural language sentences. The minimal ontology proposed in this thesis also underlies the shared semantics in a multi-agent system involving human as well as software agents interacting with each other at least partially via natural language communication. As an experimental test of our semantic theory we implement a multi-agent system in the form of a client-server architecture, involving reasoning software agents capable of parsing, proving or disproving natural language sentences sent to them as challenges by human agents operating the client interface. This proof of concept demonstrates how communication in a multi-agent system can rely on a shared minimal semantic ontology of the type we have described.

this paper. The assorted data thus far adduced provide strong support for the desirability of an account satisfying C1-C4 and show at least that any semantics not satisfying C1-C4 leaves much unexplained.