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	Default logic - Wikipedia, the free encyclopedia
		Default logic is a non-monotonic logic proposed by Ray Reiter to formalize reasoning with default assumptions.
		Deriving the antecedents of an inference rule from the consequences is a form of explanation of the consequences, and is the aim of abductive reasoning.
		a statistical default is a default with an attached upper bound on its frequency of error; in other words, the default is assumed to be an incorrect inference rule in at most that fraction of times it is applied.
	en.wikipedia.org /wiki/Default_logic (2005 words)

	Non-monotonic logic - Wikipedia, the free encyclopedia
		An example of a default assumption is that the typical bird flies.
		Logics formalizing default reasoning can be roughly divided in two categories: logics able to deal with arbitrary default assumptions (default logic, defeasible logic, and answer set programming) and logics that formalize the specific default assumption that facts that are not known to be true can be assumed false by default (closed world assumption and circumscription).
		Abductive reasoning is the process of deriving the most likely explanations of the known facts.
	en.wikipedia.org /wiki/Non-monotonic_logic (549 words)

	Non-monotonic Logic
		This theory has exactly two extensions, one in which the first default is triggered and one in which the second one is. It is easy to see that at least a default has to be triggered in any extension, and that both defaults cannot be triggered by the same extension.
		Such a problem is not even semi-decidable, the essential reason being that in general, in order to determine whether a default is triggered by a pair of sets of sentences, one has to perform a consistency check, and such checks are not computable.
		Default logic is intimately connected with certain modal approaches to non-monotonic reasoning, which belong to the family of autoepistemic logics.
	plato.stanford.edu /entries/logic-nonmonotonic (6351 words)

	Towards Efficient Default Reasoning - Niemela (ResearchIndex) (Site not responding. Last check: 2007-10-31)
		It can determine whether a default theory has an extension, whether a formula is in some extension of a default theory and whether a formula is in every extension of a default theory.
		844 A logic for default reasoning (context) - Reiter - 1980 ACM DBLP
		8 A unifying framework for nonmonotonic reasoning (context) - Niemel - 1992 ACM DBLP
	citeseer.ist.psu.edu /21922.html (572 words)

	logic_programming
		In the past, the possible relationships between default reasoning and constraints has been largely ignored by the two research communities, despite the fact that the two areas are intimately related.
		For example, the relation between priority and default is investigated deeply in a number of papers by Dr. You and his colleagues at University of Alberta.
		The procedure is based on a form of abductive reasoning, and can be used to query, for example, in AI planning and scheduling, whether there is a plan that achieves the goal, and whether there is a schedule that satisfies the specified constraints.
	www.cs.ualberta.ca /~you/Research/constraint-lp.html (2489 words)

	Liuc - Biblioteca Rostoni - Fuzzy norms, default reasoning and equilibrium selection in games under unforeseen ... (Site not responding. Last check: 2007-10-31)
		At the first step of the recursive reasoning process, each player's first hypothetical choice, given the basic vague knowledge about the game they are going to play, is calculated in term of a fuzzy expected utility function - where fuzzy utility is considered in conjunction with a possibility measure on unforeseen states.
		We end up by suggesting that the resulting equilibrium will be supported by what in default logic is called the extension of a given theory - which is characterised as a fixed point - obtained by iterately applying to it the set of accepted defaults, without introducing a contradiction.
		Is to be noted that default logic is non-monotonic, and allows for mistakes and revisions, which seems to belong to the very nature of bounded rationality.
	www.biblio.liuc.it:8080 /liucpapersita.asp?codice=107 (1331 words)

	DeReS
		Default logic was introduced by Reiter in 1980 as a tool for reasoning based on incomplete information.
		This can be accomplished through the development of much faster than presently available implementations of default logic, through the systematic studies and development of the methodology of programming with default logic, through comprehensive experimentation and by demonstrating usefulness of default logic as a computational mechanism for AI applications.
		Next, although default reasoning has a distinctly declarative character, no systematic methodology for programming and problem solving with default logic is known.
	www.cs.engr.uky.edu /~mirek/computing-with-dl.html (500 words)

	2001-16: Application of default reasoning to semantic processing under question-answering
		Default reasoning is discussed to be applicable to a variety of semantic processing algorithms, including the semantic header approach.
		The methodology of building the set of default rules is developed, capable of adding the essential entities or eliminating misleading ones to the representation of input query.
		Implementation of operational semantics for default reasoning is suggested to transform the query representation by means of conflicting default rules.
	dimacs.rutgers.edu /TechnicalReports/abstracts/2001/2001-16.html (204 words)

	Default Reasoning - The MIT Press
		Defaults in commonsense reasoning permit the generation of useful predictions in the absence of complete information.
		However, attempts to represent and reason with defaults in Al run into the problem of spurious arguments, arguments that rely on acceptable defaults but which support unacceptable conclusions.
		Geffner develops an axiomatic system based on a probabilistic and a model-theoretic semantics in which defaults are regarded as assertions whose truth or likelihood is bound to a particular context.
	mitpress.mit.edu /catalog/item/?tid=7020&ttype=2 (230 words)

	IJCAI-97 TUTORIAL MP2 (Site not responding. Last check: 2007-10-31)
		As a result, there has been a resurgence of interest in the areas of nonmonotonic reasoning and theory change, focussing less on purely theoretical insights, and more on their ability to provide a starting point for the design of the next generation of tools for developing and managing complex information systems.
		First, a number of recent studies have shown that a unified view of theory change and default reasoning leading to efficient implementations is possible.
		His research interests include default reasoning, theory change and constraint solving, and their applications in software engineering, planning and induction.
	www.ijcai.org /past/ijcai-97/CI/TUTORIAL/mp2.html (518 words)

	ESSLLI'99 course/Niemelä/Default Logic (Site not responding. Last check: 2007-10-31)
		Nonmonotonic reasoning has been one of the most active research areas in knowledge representation and reasoning since the late seventies and Reiter's default logic has turned out to be one of the most successful nonmonotonic logics.
		Default logic offers a very expressive framework for handling knowledge representation tasks in a compact, robust and flexible way even in the presence of difficult issues like the frame problem and the qualification problem.
		The objective of the course is to introduce basic default logic and its most important subclasses corresponding to logic programs, explain relevant expressivity and complexity results, present implementation methods behind the computational breakthrough and discuss application methodology for default reasoning.
	www.tcs.hut.fi /~ini/esslli99 (342 words)

	Igitur-archive (Site not responding. Last check: 2007-10-31)
		Using the KARO-architecture that we previously dened ([15, 16, 24, 25]), we introduce actions that model the (attempted) jumping to conclusions that is a fundamental part of reasoning by default.
		First it is checked whether the formula that the agent tries to jump to is a default, thereafter it is checked whether the default formula can consistently be incorporated by the agent, and if this is the case the formula is included in the agent's beliefs.
		Based on the concepts used to model the default reasoning of agents, we lookinto the dynamics of the supernormal fragment of default logic.
	igitur-archive.library.uu.nl /math/2001-0228-163958/UUindex.html (229 words)

	Defeasible Reasoning
		John Pollock's approach to defeasible reasoning consists of enumerating a set of rules that are constructive and effectively computable, and that aim at describing how an ideal cognitive agent builds up a rich set of beliefs, beginning with a relatively sparse data set (consisting of beliefs about immediate sensory appearances, apparent memories, and such things).
		On the larger question of the relation between belief revision and defeasible reasoning, there are two possibilities: that a theory of defeasible reasoning should be grounded in a theory of belief revision, and that a theory of belief revision should be grounded in a theory of defeasible reasoning.
		Default conditionals are not allowed to be nested within other default conditionals, or within the scope of the usual Boolean operators of propositional logic (negation, conjunction, disjunction, material conditional).
	plato.stanford.edu /entries/reasoning-defeasible (12374 words)

	Nonmonotonic Consequences In Default Domain Theory - Zhang, Rounds (ResearchIndex) (Site not responding. Last check: 2007-10-31)
		Default domain theory is a framework for representing and reasoning about commonsense knowledge.
		Although this theory is motivated by ideas in Reiter's work on default logic, it is in some sense a dual framework.
		Domain theory, which is a well established tool for representing partial information in the semantics of programming languages, is adopted as the basis for constructing partial...
	citeseer.ifi.unizh.ch /9347.html (640 words)

	Theorist
		So arose this idea of having assumption-based reasoning where the forms of the possible hypotheses, as well as the facts are provided by the user.
		The second, prediction is where the explanandum is unknown, and the problem is to determine whether to predict the explanandum or not (forming a formalization of default reasoning).
		A common reasoning strategy is, given an observation, to explain it (using normality and abnormality assumptions) and then make predictions (using normality assumptions).
	www.cs.ubc.ca /spider/poole/theorist.html (1438 words)

	Automated Reasoning
		Reasoning is the ability to make inferences, and automated reasoning is concerned with the building of computing systems that automate this process.
		The reason is, of course, that the statement of the completeness of LK only has to assert, for each entailment relation, the existence of a proof tree but a reasoning program has the more difficult task of actually having to construct one.
		The goal of automated reasoning has been to further extend the machine's reach into the realm of deduction where they can be used as reasoning assistants in helping their users establish truth through proof.
	plato.stanford.edu /entries/reasoning-automated (12197 words)

	[No title] (Site not responding. Last check: 2007-10-31)
		However, it is necessary for future developments that demand for more sophisticated reasoning rules.
		Default Rules Default reasoning rules are built into the agents.
		Running Reasoning Simulation Test The purpose of the simulation test is to ensure the distributed reasoning among agents funcations correctly without any Java agent implementations.
	www.cs.umbc.edu /~hchen4/hpl/readme.txt (1796 words)

	Reasoning about Uncertainty - The MIT Press
		While the ideas presented are formalized in terms of definitions and theorems, the emphasis is on the philosophy of representing and reasoning about uncertainty; the material is accessible and relevant to researchers and students in many fields, including computer science, artificial intelligence, economics (particularly game theory), mathematics, philosophy, and statistics.
		He discusses knowledge and belief; default reasoning and the semantics of default; reasoning about counterfactuals, and combining probability and counterfactuals; belief revision; first-order modal logic; and statistics and beliefs.
		Terms such as 'true,' 'certain,' 'plausible,' 'possible,' 'believed,' 'known,' 'default,' 'relevant,' 'independent,' and 'preferred' are given rigorous semantical and syntactical analyses, and their interrelationships explicated and exemplified.
	mitpress.mit.edu /catalog/item/default.asp?tid=9952&ttype=2 (459 words)

	Belief Revision and Default Reasoning: Syntax-Based Approaches - Nebel (ResearchIndex) (Site not responding. Last check: 2007-10-31)
		Default reasoning leads to logical nonmonotonicity, i.e., the set of consequences does not grow monotonically with the set of premises.
		Nebel, B. Belief revision and default reasoning: Syntax-based approaches.
		72 Belief revision and default reasoning: syntax-based approach..
	citeseer.ist.psu.edu /nebel91belief.html (726 words)

	A Sequent Calculus for Intuitionistic Default Logic (ResearchIndex) (Site not responding. Last check: 2007-10-31)
		Abstract: Current research on non-monotonic reasoning shows growing interest on implementation details, so the need for concrete calculi formalizing non-monotonic logics is clearly recognized.
		On the other hand, there is also an increased number of works combining intuitionistic logic with various kinds of non-monotonic formalisms.
		As a case in point, intuitionistic versions of both default and autoepistemic logics have been proposed, and tight connections between intuitionistic logic and logic programs...
	citeseer.ifi.unizh.ch /26878.html (492 words)

	TCS - Research - Publications - Lexicographic Ordering as a Basis of Priorities in Default Reasoning (Site not responding. Last check: 2007-10-31)
		This logic extends Reiter's default logic and uses a priority mechanism that is based on lexicographic comparison.
		Questions concerning the existence of extensions, monotonicity of default reasoning with respect to priorities, alternative interpretations of partiality in priorities, and computational complexity of prioritized default logic are investigated.
		The first is based on normal default theories and the second is based on prerequisite-free normal default theories.
	www.tcs.hut.fi /Publications/info/bibdb.HUT-TCS-A41.shtml (243 words)

	Provability logic for default reasoning (Site not responding. Last check: 2007-10-31)
		Then, a suitable self-referencial sentence is associated with a default theory.
		Hence, KD4Z characterizes default logic: it is an amalgamated formalism that allows formulas of the language to represent metalogical constructions.
		Differently from the "negation as failure to prove" paradigm, in which families of modal logics can be used to embedd default logics, the proposed "modal provability" approach leads to a single logic.
	www.dis.uniroma1.it /~ai/citations/amat-etal-94-c.html (203 words)

	An Overview of Nonmonotonic Reasoning and Logic Programming (Site not responding. Last check: 2007-10-31)
		The focus of this paper is nonmonotonic reasoning as it relates to logic programming.
		I then provide a summary which includes an assessment of the field and what must be done to further research in nonmonotonic reasoning and logic programming.
		An approach to default reasoning based on a first-order conditional logic: revised report.
	prism.cs.umd.edu /papers/Min93:overview/lpnmr.overview.jlp.html (2723 words)

	Cognitive Systems Laboratory Publications
		"Reasoning With Qualitative Probabilities Can Be Tractable," UCLA, Cognitive Systems Laboratory, Computer Science Department, Technical Report (R-176), in Dubois, D., Wellman, M. P., D'Ambrosio B. and Smets, P. (Eds), Proceedings of the 8th Conference on Uncertainty in Artificial Intelligence, Stanford, CA, Morgan Kaufmann Publishers, San Mateo, CA, 112-120, 1992.
		H. Geffner, "Default Reasoning, Minimality and Coherence," UCLA Cognitive Systems Laboratory, Technical Report CSD-890037 (R-125), February 1989, in Proceedings, First International Conference on Principles of Knowledge Representation and Reasoning (KR'89), Toronto, Canada, 137-148, May 1989.
		Pearl, J., "On Evidential Reasoning in a Hierarchy of Hypotheses," UCLA Computer Science Department Technical Report 850032 (R-51); Research Note, Journal of Artificial Intelligence, 28 (1), 9-15, February 1986.
	bayes.cs.ucla.edu /bib.html (8313 words)

	Default reasoning
		This is a very common from of non-monotonic reasoning.
		Non-Monotonic reasoning is generic descriptions of a class of reasoning.
		In Default logic any nonmonotonic expressions are rules of inference rather than expressions.
	www.cs.cf.ac.uk /Dave/AI2/node79.html (319 words)

	Plausibility Measures and Default Reasoning (Site not responding. Last check: 2007-10-31)
		Earlier version appeared under the title Plausibility Measures and Default Reasoning in Thirteenth National Conf.
		In recent years, a number of different semantics for defaults have been proposed, such as preferential structures, $\epsilon$-semantics, possibilistic structures, and $\kappa$-rankings, that have been shown to be characterized by the same set of axioms, known as the KLM properties.
		In particular, it is easily seen to hold for all the proposals made in the literature.
	www.eecs.harvard.edu /~nir/Abstracts/FrH5Full.html (183 words)

	Stratification: The Computational Base of a System for Default Reasoning
		One of the most promising ways of easing this problem and developing powerful implementations is to split a default theory into smaller parts and compute extensions in a modular, "local'' way.
		Up to now this idea was only followed for Reiter's default logic, yet it is also relevant to other variants of default logic which have found increasing recognition in the past years.
		This work defines the formal basis for a Web-based default reasoning system which is under development at our institution.
	csdl.computer.org /comp/proceedings/ictai/1997/8203/00/82030165abs.htm (193 words)

	Dr. Rina Dechter @ UCI
		The overall aim of my research is to devise methods of automated reasoning via the understanding and exploitation of tractable classes of reasoning tasks.
		Constraint networks are used to model mundane cognitive tasks (e.g., vision, language comprehension, default reasoning, abduction) as well as applications such as scheduling, design, and diagnosis which require high levels of human expertise.
		Throughout my research I have investigated the role of the knowledge structure in enabling fast reasoning which had led to the identification of several structure-based tractable islands.
	www.ics.uci.edu /~dechter/about/research-interests.html (1720 words)

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