Results 1  10
of
54
Modelling a PublicKey Infrastructure
, 1996
"... A global publickey infrastructure (PKI), components of which are emerging in the near future, is a prerequisite for security in distributed systems and for electronic commerce. The purpose of this paper is to propose an approach to modelling and reasoning about a PKI from a user Alice's p ..."
Abstract

Cited by 162 (2 self)
 Add to MetaCart
A global publickey infrastructure (PKI), components of which are emerging in the near future, is a prerequisite for security in distributed systems and for electronic commerce. The purpose of this paper is to propose an approach to modelling and reasoning about a PKI from a user Alice's point of view. Her view, from which she draws conclusions about the authenticity of other entities' public keys and possibly about the trustworthiness of other entities, consists of statements about which public keys she believes to be authentic and which entities she believes to be trustworthy, as well as a collection of certificates and recommendations obtained or retrieved from the PKI. The model takes into account recommendations for the trustworthiness of entities. Furthermore, it includes confidence values for statements and can exploit arbitrary certification structures containing multiple intersecting certification paths to achieve a higher confidence value than for any single c...
Using firstorder logic to reason about policies
 In Proc. 16th IEEE Computer Security Foundations Workshop (CSFW’03
, 2003
"... A policy describes the conditions under which an action is permitted or forbidden. We show that a fragment of (multisorted) firstorder logic can be used to represent and reason about policies. Because we use firstorder logic, policies have a clear syntax and semantics. We show that further restri ..."
Abstract

Cited by 105 (7 self)
 Add to MetaCart
(Show Context)
A policy describes the conditions under which an action is permitted or forbidden. We show that a fragment of (multisorted) firstorder logic can be used to represent and reason about policies. Because we use firstorder logic, policies have a clear syntax and semantics. We show that further restricting the fragment results in a language that is still quite expressive yet is also tractable. More precisely, questions about entailment, such as ‘May Alice access the file?’, can be answered in time that is a loworder polynomial (indeed, almost linear in some cases), as can questions about the consistency of policy sets.
Logic Programming and Knowledge Representation  the AProlog perspective
 Artificial Intelligence
, 2002
"... In this paper we give a short introduction to logic programming approach to knowledge representation and reasoning. The intention is to help the reader to develop a 'feel' for the field's history and some of its recent developments. The discussion is mainly limited to logic programs u ..."
Abstract

Cited by 98 (1 self)
 Add to MetaCart
(Show Context)
In this paper we give a short introduction to logic programming approach to knowledge representation and reasoning. The intention is to help the reader to develop a 'feel' for the field's history and some of its recent developments. The discussion is mainly limited to logic programs under the answer set semantics. For understanding of approaches to logic programming build on wellfounded semantics, general theories of argumentation, abductive reasoning, etc., the reader is referred to other publications.
Event calculus reasoning through satisfiability
 Journal of Logic and Computation
, 2004
"... This is a precopyediting, authorproduced PDF of an article accepted for publication in the Journal of Logic and Computation following peer review. The definitive publisherauthenticated version (Mueller, Erik T. (2004). Event calculus reasoning through satisfiability. Journal of Logic and Computa ..."
Abstract

Cited by 36 (8 self)
 Add to MetaCart
This is a precopyediting, authorproduced PDF of an article accepted for publication in the Journal of Logic and Computation following peer review. The definitive publisherauthenticated version (Mueller, Erik T. (2004). Event calculus reasoning through satisfiability. Journal of Logic and Computation, 14(5), 703–730.) is available online at:
The Stable Models of a Predicate Logic Program
 Journal of Logic Programming
, 1992
"... this paper we investigate and solve the problem classifying the Turing complexity of stable models of finite and recursive predicate logic programs. GelfondLifschitz [7] introduced the concept of a stable model M of a Predicate Logic Program P . Here we show that, up to a recursive 11 coding, the ..."
Abstract

Cited by 36 (15 self)
 Add to MetaCart
(Show Context)
this paper we investigate and solve the problem classifying the Turing complexity of stable models of finite and recursive predicate logic programs. GelfondLifschitz [7] introduced the concept of a stable model M of a Predicate Logic Program P . Here we show that, up to a recursive 11 coding, the set of all stable models of finite Predicate Logic Programs and the 5
Understanding scriptbased stories using commonsense reasoning
 Cognitive Systems Research
, 2002
"... reasoning, reasoning about action and change This paper investigates the use of commonsense reasoning to understand texts involving stereotypical activities or scripts. We present a system that understands news stories involving four terrorism scripts. The system (1) builds a commonsense reasoning p ..."
Abstract

Cited by 29 (4 self)
 Add to MetaCart
(Show Context)
reasoning, reasoning about action and change This paper investigates the use of commonsense reasoning to understand texts involving stereotypical activities or scripts. We present a system that understands news stories involving four terrorism scripts. The system (1) builds a commonsense reasoning problem given an information extraction template representing a terrorist incident, and (2) uses commonsense reasoning and a commonsense knowledge base to build a model of the terrorist incident. The reasoning problem, commonsense knowledge base, and model are expressed in the classical logic event calculus. The system was developed using the MUC3 and MUC4 development data set. We present the results of running the system on the MUC3 and MUC4 test data sets, using manually generated answer key templates and templates generated automatically by two MUC4 information extraction systems. We present a detailed analysis of the models produced by the system given automatically generated templates. We present methods for answering questions based on the models produced by our system. We assess the portability of the system by extending it to handle 10 scripts frequent in Project Gutenberg American literature texts. 1
A formal foundation for XrML
 In Proc. 17th IEEE Computer Security Foundations Workshop
, 2004
"... XrML is becoming a popular language in industry for writing software licenses. The semantics for XrML is implicitly given by an algorithm that determines if a permission follows from a set of licenses. We focus on a fragment of the language and use it to highlight some problematic aspects of the alg ..."
Abstract

Cited by 25 (6 self)
 Add to MetaCart
(Show Context)
XrML is becoming a popular language in industry for writing software licenses. The semantics for XrML is implicitly given by an algorithm that determines if a permission follows from a set of licenses. We focus on a fragment of the language and use it to highlight some problematic aspects of the algorithm. We then correct the problems, introduce formal semantics, and show that our semantics captures the (corrected) algorithm. Next, we consider the complexity of determining if a permission is implied by a set of XrML licenses. We prove that the general problem is undecidable, but it is polynomialtime computable for an expressive fragment of the language. We extend XrML to capture a wider range of licenses by adding negation to the language. Finally, we discuss the key differences between XrML and MPEG21, an international standard based on XrML.
Towards an efficient tableau method for boolean circuit satisfiability testing
 Computational Logic  CL 2000; First Internatinal Conference
, 2000
"... Boolean circuits oer a natural, structured, and compact representation of Boolean functions for many application domains. In this paper a tableau method for solving satisfiability problems for Boolean circuits is devised. The method employs a direct cut rule combined with deterministic deduction r ..."
Abstract

Cited by 23 (7 self)
 Add to MetaCart
(Show Context)
Boolean circuits oer a natural, structured, and compact representation of Boolean functions for many application domains. In this paper a tableau method for solving satisfiability problems for Boolean circuits is devised. The method employs a direct cut rule combined with deterministic deduction rules. Simplification rules for circuits and a search heuristic attempting to minimize the search space are developed. Experiments in symbolic model checking domain indicate that the method is competitive against stateoftheart satisfiability checking techniques and a promising basis for further work.
The expressiveness of locally stratified programs
 Annals of Mathematics and Artificial Intelligence
, 1995
"... This paper completes an investigation of the logical expressibility of finite, locally stratified, general logic programs. We show that every hyperarithmetic set can be defined by a suitably chosen locally stratified logic program (as a set of values of a predicate over its perfect model). This is a ..."
Abstract

Cited by 15 (2 self)
 Add to MetaCart
(Show Context)
This paper completes an investigation of the logical expressibility of finite, locally stratified, general logic programs. We show that every hyperarithmetic set can be defined by a suitably chosen locally stratified logic program (as a set of values of a predicate over its perfect model). This is an optimal result, since the perfect model of a locally stratified program is itself an implicitly definable hyperarithmetic set (under a recursive coding of the Herbrand base); hence to