Robert Kowalski

Verified

Robert verified their affiliation via an institutional email.

Learn more

Verified

Robert verified their affiliation via an institutional email.

Learn more

• PhD
• Professor Emeritus at Imperial College London

For the most part, insurance contracts are monolithic, text-based documents, written in unstructured natural language interspersed with technical terms. This means that the many provisions embedded in the contract, both explicit and implicit, are difficult for both humans and computers to understand and process. Efforts to make insurance contracts...

L’article rappelle le contexte scientifique de l’émergence de Prolog et évoque les échanges fructueux entre Alain Colmerauer à Marseille et Robert Kowalski à Edimbourg qui ont donné naissance à la Programmation Logique. The article recalls the scientific context of the emergence of Prolog and evokes the fruitful exchanges between Alain Colmerauer...

Logical English (LE) is a natural language syntax for pure Prolog and other logic programming languages, such as ASP and s(CASP). Its main applications until now have been to explore the representation of a wide range of legal texts, helping to identify ambiguities, explore alternative representations of the same text, and compare the logical conse...

Logic programs and imperative programs employ different notions of computing. Logic programs compute by proving that a goal is a logical consequence of the program, or by showing that the goal is true in a model defined by the program. Imperative programs compute by starting from an initial state, executing actions to transition from one state to t...

In this paper we present the key features of Logical English as syntactic sugar for logic programming languages such as pure Prolog, ASP and s(CASP); and we highlight two application areas, coding legal rules, and teaching logic as a computer language for children.KeywordsLogical EnglishPrologLawEducation

In this paper, we present an informal introduction to Logical English (LE) and illustrate its use to standardise the legal wording of the Automatic Early Termination (AET) clauses of International Swaps and Derivatives Association (ISDA) Agreements. LE can be viewed both as an alternative to conventional legal English for expressing legal documents...

Logical English (LE) is syntactic sugar for logic programs, which are collections of facts and rules of the form conclusion if conditions. In this paper, we focus on legal applications of LE and the use of meta-(or higher-order) predicates to represent propositional attitudes, such as permission, obligation, notification of a message and designatio...

Logical English (LE) is a controlled natural language (CNL), which is designed to be both computer-executable and readable by English speakers without special training. It is intended for use as a general-purpose computer language. But because it is inspired in part by the language of law, LE is especially well-suited for legal applications. In thi...

Logical English (LE) is a controlled natural language, in which English sentences are translated into LPS, which is an extension of logic programming, implemented in Prolog. The ultimate goal of LE is to serve as a general-purpose computer language, which can be understood by a reader without any training in computing, logic or mathematics. It is...

Programming environments have evolved from purely text based to using graphical user interfaces, and now we see a move toward web-based interfaces, such as Jupyter. Web-based interfaces allow for the creation of interactive documents that consist of text and programs, as well as their output. The output can be rendered using web technology as, for...

Formalising deontic concepts, such as obligation, prohibition and permission, is normally carried out in a modal logic with a possible world semantics, in which some worlds are better than others. The main focus in these logics is on inferring logical consequences, for example inferring that the obligation Oq is a logical consequence of the obligat...

Programming environments have evolved from purely text based to using graphical user interfaces, and now we see a move towards web based interfaces, such as Jupyter. Web based interfaces allow for the creation of interactive documents that consist of text and programs, as well as their output. The output can be rendered using web technology as, e.g...

In modal deontic logics, the focus is on inferring logical consequences, for example inferring whether an obligation O mail, to mail a letter, logically implies O [mail or burn], an obligation to mail or burn the letter. Here I present an alternative approach in which obligations are sentences (such as mail) in first-order logic (FOL), and the focu...

In previous work, we proposed a logic-based framework in which computation is the execution of actions in an attempt to make reactive rules of the form if antecedent then consequent true in a canonical model of a logic program determined by an initial state, sequence of events, and the resulting sequence of subsequent states. In this model-theoreti...

In this paper we propose a logic-based, framework inspired by artificial intelligence, but scaled down for practical database and programming applications. Computation in the framework is viewed as the task of generating a sequence of state transitions, with the purpose of making an agent’s goals all true. States are represented by sets of atomic s...

This commentary reflects upon the way the topics addressed in the Logic for Problem Solving book have developed since the first version appeared as lecture notes in 1974. Arguably, many of the developments have had an impact, not only in computing, but also more widely in such fields as mathematical , philosophical and informal logic. But just as i...

Typical reactive system languages are programmed by means of rules of the form if antecedent then consequent. However, despite their seemingly logical character, hardly any reactive system languages give such rules a logical interpretation. In this paper, we investigate a simplified reactive system language KELPS, in which rules are universally qua...

Volume 9, Computational Logic (Joerg Siekmann, editor). In the History of Logic series, edited by Dov Gabbay and John Woods, Elsevier, 2014, pp 523-569.

Logic programming emerged in the 1970s from debates concerning procedural versus declarative representations of knowledge in artificial intelligence. In those days, declarative representations were associated mainly with bottom-up proof procedures, such as hyper-resolution. The development of logic programming showed that procedural representations...

Computer Science today lacks a unified view of Computing. Instead, the main subareas, most notably artificial intelligence, database systems and programming languages, offer different and often competing approaches to knowledge representation, problem-solving and computation. In this paper we propose a unifying logic-based, framework for Computing,...

Production of official statistics frequently requires expert judgement to evaluate and reconcile data of unknown and varying quality from multiple and potentially conflicting sources. Moreover, exceptional events may be difficult to incorporate in modelled estimates. Computational logic provides a methodology and tools for incorporating analyst's j...

Knowledge representation and reasoning using computational logic: an annotated bibliography. (DOCX)

We sketch a logic-based framework in which computation consists of performing actions to generate a sequence of states, with the purpose of making a set of reactive rules in the logical form antecedents ( consequents all true. The antecedents of the rules are conjunctions of past or present conditions and events, and the consequents of the rules ar...

Teleo-reactive (TR) programs are a variety of production systems with a destructively updated database that represents the current state of the environment. They combine proactive behaviour, which is goal-oriented, with reactive behaviour, which is sensitive to the changing environment. They can take advantage of situations in which the environment...

Marek Sergot’s technical contributions range over different subjects. He has developed a series of novel ideas and formal methods bridging different research domains, such as artificial intelligence, computational logic, philosophical logic, legal theory, artificial intelligence and law, multi-agent systems and bioinformatics. By combining his bac...

WUENIC is a rule-based system implemented as a logic program, developed by WHO and UNICEF for estimating global, country by country, infant immunization coverage. It possesses many of the characteristics of rule-based legislation, facilitating decisions that are consistent, transparent and replicable. In this paper, we focus on knowledge representa...

What is the relationship between language and thought? The quest to create artificial intelligence may have come up with some unexpected answers

This earlier draft of a book of the same title, published in July 2011 by Cambridge University Press, presents the principles of Computational Logic, so that they can be applied in everyday life. I have written the main part of the book informally, both to reach a wider audience and to argue more convincingly that Computational Logic is useful for...

In this paper we present an agent language that combines agent functionality with a state transition theory and model-theoretic semantics. The language is based on abductive logic programming (ALP), but employs a simplified state-free syntax, with an operational semantics that uses destructive updates to manipulate a database, which represents the...

Research in AI has built upon the tools and techniques of many different disciplines, including formal logic, probability theory, decision theory, management science, linguistics and philosophy. However, the application of these disciplines in AI has necessitated the development of many enhancements and extensions. Among the most powerful of these...

In this paper we present an agent language that combines agent functionality with an action theory and model-theoretic semantics. The language is based on abductive logic programming (ALP), but employs a simplified state-free syntax, with an operational semantics that uses destructive assignment to manipulate a database, which represents the curren...

Reasoning with conditionals has been the focus of much research in Cognitive Psychology, but has attracted comparatively less attention in Artificial Intelligence. However, if you scratch below the surface, it soon becomes apparent that conditionals, in one form or another, are arguably the most common form of knowledge representation in Artificial...

The practical benefits of computational logic need not be limited to mathematics and computing. As this book shows, ordinary people in their everyday lives can profit from the recent advances that have been developed for artificial intelligence. The book draws upon related developments in various fields from philosophy to psychology and law. It pay...

In this paper we argue the case for integrating the distinctive functionalities of logic programs and production systems within an abductive logic programming agent framework. In this framework, logic programs function as an agent’s beliefs and production rules function as the agent’s goals. The semantics and proof procedures are based on abductive...

Assumption-Based Argumentation (ABA) [4, 3, 27, 11, 12, 20, 22] was developed, starting in the 90s, as a computational framework to reconcile and generalise most existing approaches to default reasoning [24, 25, 4, 3, 27, 26]. ABA was inspired by Dung’s preferred extension semantics for logic programming [9, 7], with its dialectical interpretation...

The authors describe a logic programming approach to the representation of legislative texts. They consider the potential uses of simple systems which incorporate a single, fixed interpretation of a text. These include assisting in the routine administration of complex areas of the law. The authors also consider the possibility of constructing more...

In this paper we analyse the differences between rational and reactive agent architectures, and propose a uniform agent architecture that aims to capture both as special cases. For this purpose we employ a proof procedure, to control the agent's behaviour, which combines definitions with integrity constraints. The proof procedure is general, and ha...

We present a family of dialectic proof procedures for the admissibility semantics of assumption-based argumentation. These proof procedures are defined for any conventional logic formulated as a collection of inference rules and show how any such logic can be extended to a dialectic argumentation system.The proof procedures find a set of assumption...

The linguistic style in which legislation is normally written has many similarities with the language of logic programming. However, examples of legal language taken from the British Nationality Act 1981, the University of Michigan lease termination clause, and the London Underground emergency notice suggest several ways in which the basic model of...

Logic and objects can be combined and reconciled in at least three main ways. The simplest and most conservative way is to use logic to describe OO systems. This is useful for specifying and proving properties of OO systems. A more ambitious, but also straight-forward way is to use logic to implement OO methods. Used in this way, logic can implemen...

Abductive logic programming (ALP) can be used to model reactive, proactive and pre-active thinking in intelligent agents. Reactive thinking assimilates observations of changes in the environment, whereas proactive thinking reduces goals to sub-goals and ultimately to candidate actions. Pre-active thinking generates logical consequences of candidate...

Many real world conflicts can be understood in terms of logical inconsistencies between goals. In this paper, I present an approach to conflict resolution that unifies logic, goalreduction and condition-action rules in a cognitive model of intelligent agent. The approach uses goal hierarchies to reconcile goal conflicts by finding alternative, logi...

We present a succession of presentations of an argumentation-theoretic proof procedure that applies uniformly to a wide variety of logics for default reasoning, including Theorist, default logic, logic programming, autoepistemic logic, non-monotonic modal logic and certain instances of circumscription.

Logic programming emerged in the early 1970s from a convergence of work in the fields of automated theorem proving (q.v.), artificial intelligence (q.v.), and formal languages (q.v.).

In this paper we describe a distributed object oriented logic programming language in which an object is a collection of threads deductively accessing and updating a shared logic program. The key features of the language, such as static and dynamic object ...

In this paper we dene an abstract proof procedure for default reasoning. The proof procedure is abstract because it applies to any logic for default reasoning which can be dened in an abstract argumentation-theoretic framework [3]. The abstract framework includes default logic, logic programming, autoepistemic logic, non-monotonic modal logic and c...

This paper is a survey and critical overview of recent work on the extension of Logic Programming to perform Abductive Reasoning (Abductive Logic Programming). It updates the earlier paper "Abductive Logic Programming" [88]. We outline the general framework of Abduction and its applications to Knowledge Assimilation and Default Reasoning; we descri...

In this paper, to compare the situation calculus and event calculus we formulate both as logic programs and prove properties of these by reasoning with their completions augmented with induction. We thus show that the situation calculus and event calculus imply one another. Whereas our derivation of the event calculus from the situation calculus re...

We outline a formal theory of argumentationtheoretic reasoning which unifies and generalises many existing approaches to default reasoning, and which promises to be useful for practical reasoning in general and legal reasoning in particular. We discuss an extension of the argumentation theory to the problem of reconciling conflicting arguments. 1 I...

This paper proposes a Theorem-Proving approach to Constraint Logic Programming, the TPCLP framework. The framework combines the use of definitions, as in ordinary logic programming, with the use of integrity constraints, rather than built-in constraint solvers, for constraint handling. Thus the programmer can choose to represent knowledge either in...

In this paper we present an extension of logic programming (LP) that is suitable not only for the "rational" component of a single agent but also for the "reactive" component and which can encompass multi-agent systems. The extension to multi-agent systems, in particular, arguably brings to LP the main benefits of object-orientation, including enca...

this paper to improve its efficiency.

This paper presents the TPCALP framework, a theorem-proving approach which aims to unify Abductive Logic Programming (ALP), Constraint Logic Programming (CLP) and Semantic Query Optimization (SQO). The framework combines the use of definitions, as in ordinary logic programming, with the use of integrity constraints, as in ALP and SQO. The programme...

. We present a methodology for proving that any program transformation which preserves the least Herbrand model semantics when applied to sets of Horn clauses also preserves all semantics for normal logic programming that can be formulated in argumentation-theoretic terms [3, 4, 16]. These include stable model, partial stable model, preferred exten...

Arguably, model theory serves two main functions: (1) to explain the relationship between language and experience, and (2) to specify the notion of logical consequence. In this paper I shall propose the notion of `knowledge assimilation', the assimilation of new information into a knowledge base, as an alternative understanding of the way in which...

The notion of assumption-based framework generalises and refines the use of abduction to give a formalisation of non-monotonic reasoning. In this framework, a sentence is a non-monotonic consequence of a theory if it can be derived monotonically from a theory extended by means of acceptable assumptions. The notion of acceptability for such assumpti...

We present an abstract framework for default reasoning, which includes Theorist, default logic, logic programming, autoepistemic logic, non-monotonic modal logics, and certain instances of circumscription as special cases. The framework can be understood as a generalisation of Theorist. The generalisation allows any theory formulated in a monotonic...

In this paper we analyse the similarities and differences between rational and reactive agent architectures, and propose a unified architecture that aims to capture both as special cases. For this purpose we employ a proof procedure as the thinking component of the agent. The proof procedure combines definitions with integrity constraints. It uses...

. We present an extension of Logic Programming (LP) which, in addition to ordinary LP clauses, also includes integrity constraints, explicit representation of disjunction in the bodies of clauses and in goals, and suspension of atoms as in concurrent logic languages. The resulting framework aims to unify Constraint Logic Programming (CLP), Abductiv...

. We present a proof procedure that combines backward reasoning with logic programs and forward reasoning with integrity constraints. We illustrate the use of the proof procedure as the inference engine underlying agents. Roughly speaking, the backward reasoning component of the proof procedure is responsible for the deliberative behaviour of agent...

In this paper we present an extension of logic programming (LP) that is suitable not only for the “rational” component of a single agent but also for the “reactive” component and that can encompass multi‐agent systems. We modify an earlier abductive proof procedure and embed it within an agent cycle. The proof procedure incorporates abduction, defi...

This paper presents the TPCALP framework, a theorem-proving approach which aims to unify Abductive Logic Programming (ALP), Constraint Logic Programming (CLP) and Semantic Query Optimization (SQO). The framework combines the use of definitions, as in ordinary logic programming, with the use of integrity constraints, as in ALP and SQO. The programme...

We outline a proof procedure which combines reasoning with defined predicates together with reasoning with undefined, abducible, predicates. Defined predicates are defined in if-and-only-if form. Abducible predicates are constrained by means of integrity constraints. Given an initial query, the task of the proof procedure is to construct a definiti...

We present an abstract framework for default reasoning, which includes Theorist, default logic, logic programming, autoepistemic logic, non-monotonic modal logics, and certain instances of circumscription as special cases. The framework can be understood as a generalisation of Theorist. The generalisation allows any theory formulated in a monotonic...

We apply logic program development technology to define abstract proof procedures, in the form of logic programs, for computing the admissibility semantics for default reasoning proposed in [2]. The proof procedures are derived from a formal specification. The derivation guarantees the soundness of the proof procedures. The completeness of the proo...

Without Abstract

In this paper we explore the thesis that the role of argumentation in practical reasoning in general and legal reasoning in particular is to justify the use of defeasible rules to derive a conclusion in preference to the use of other defeasible rules to derive a conflicting conclusion. The defeasibility of rules is expressed by means of non-provabi...

In this paper we explore the thesis that the role of argumentation in practical reasoning in general and legal reasoning in particular is to justify the use of defeasible rules to derive a conclusion in preference to the use of other defeasible rules to derive a conflicting conclusion. The defeasibility of rules is expressed by means of non-provabi...

: In this paper I outline an attempt to reconcile the traditional Artificial Intelligence notion of a logic-based rational agent with the contrary notion of a reactive agent that acts "instinctively" in response to conditions that arise in its environment. For this purpose, I will use the tools of meta-logic programming to define the observation-th...

The event calculus was proposed as a formalism for reasoning about time and events. Through the years, however, a much simpler variant (SEC) of the original calculus (EC) has proved more useful in practice.

In this paper we study a form of abductive logic programming which combines default and non-default abducibles and employs retractibles in integrity constraints. We also present a transformation from abductive to normal logic programs, which is correct and complete with respect to many semantics. These are all the semantics that can be formulated i...

The function of air traffic flow management (ATFM) is to ensure that air traffic operates within adequate margins of safety. Existing ATFM systems are manual which are over-conservative in. operation resulting in under-utilisation of available airspace. As well as being costly, such systems are unable to cope with increased demand for air travel in...

This is the second in a series of workshops that are bringing together researchers from the theoretical end of both the logic programming and artificial intelligence communities to discuss their mutual interests. This workshop emphasizes the relationship between logic programming and non-monotonic reasoning. Topics Stable Semantics • Autoepistemic...

This paper is a survey and critical overview of recent work on the extension of logic programming to perform abductive reasoning (abductive logic programming). We outline the general framework of abduction and its applications to knowledge assimilation and default reasoning; and we introduce an argumentation-theoretic approach to the use of abducti...

This paper investigates a special case of the event calculus, concerned with database updates. It discusses the way relational databases, historical databases, modal logic, the situation calculus, and case semantics deal with database updates and compares the event calculus with the situation calculus in detail. It argues that the event calculus ca...

Logic Programming enjoys a relatively good relationship between its theory and its practice. Nonetheless, this relationship needs to be improved, and doing so is an important direction for research in the future. The European Community Basic Research Project, Compulog, and the more general network of excellence, Compulog-net, are concerned with dev...

The linguistic style in which legislation is normally written has many similarities with the language of logic programming. However, examples of legal language taken from the British Nationality Act 1981, the University of Michigan lease termination clause, and the London Underground emergency notice suggest several ways in which the basic model of...

This paper investigates the effects of parallelism on blackboard system scheduling. A parallel blackboard system is described that allows multiple knowledge source instantiations to execute in parallel using a shared-memory blackboard approach. New classes ...

The London underground emergency notice can be understood as a program, written in English, to regulate human behaviour. It can also serve as an example of the linguistic style of the more human-oriented computer languages of the future.

A practical approach to temporal reasoning based on the event calculus is explored in the context of air traffic flow management (ATFM). The work reported is part of the EQUATOR (ESPRIT project 2409). ATFM demonstrates a requirement for managing objects in time and space, real-time characteristics and large scale. Current ATFM procedures are essent...

We extend logic programming to deal with default reasoning by allowing the explicit representation of exceptions in addition to general rules. To formalise this extension, we modify the answer set semantics of Gelfond and Lifschitz, which allows both classical negation and negation as failure. We also propose a transformation which eliminates exce...

The ultimate goal of the Basic Research Action, Compulog, is to develop the use of logic for all aspects of computation. This includes not only the development of a single logic for representing programs, program specifications, databases, and knowledge representations in artificial intelligence, but also the development of logic-based management t...

In trying to make predictions about a field so young as computing, it is useful to draw comparisons with a related and much older field such as law.