3,320 research outputs found
Approximate reasoning using terminological models
Term Subsumption Systems (TSS) form a knowledge-representation scheme in AI that can express the defining characteristics of concepts through a formal language that has a well-defined semantics and incorporates a reasoning mechanism that can deduce whether one concept subsumes another. However, TSS's have very limited ability to deal with the issue of uncertainty in knowledge bases. The objective of this research is to address issues in combining approximate reasoning with term subsumption systems. To do this, we have extended an existing AI architecture (CLASP) that is built on the top of a term subsumption system (LOOM). First, the assertional component of LOOM has been extended for asserting and representing uncertain propositions. Second, we have extended the pattern matcher of CLASP for plausible rule-based inferences. Third, an approximate reasoning model has been added to facilitate various kinds of approximate reasoning. And finally, the issue of inconsistency in truth values due to inheritance is addressed using justification of those values. This architecture enhances the reasoning capabilities of expert systems by providing support for reasoning under uncertainty using knowledge captured in TSS. Also, as definitional knowledge is explicit and separate from heuristic knowledge for plausible inferences, the maintainability of expert systems could be improved
Relational Symbolic Execution
Symbolic execution is a classical program analysis technique used to show
that programs satisfy or violate given specifications. In this work we
generalize symbolic execution to support program analysis for relational
specifications in the form of relational properties - these are properties
about two runs of two programs on related inputs, or about two executions of a
single program on related inputs. Relational properties are useful to formalize
notions in security and privacy, and to reason about program optimizations. We
design a relational symbolic execution engine, named RelSym which supports
interactive refutation, as well as proving of relational properties for
programs written in a language with arrays and for-like loops
Automatic extraction of knowledge from web documents
A large amount of digital information available is written as text documents in the form of web pages, reports, papers, emails, etc. Extracting the knowledge of interest from such documents from multiple sources in a timely fashion is therefore crucial. This paper provides an update on the Artequakt system which uses natural language tools to automatically extract knowledge about artists from multiple documents based on a predefined ontology. The ontology represents the type and form of knowledge to extract. This knowledge is then used to generate tailored biographies. The information extraction process of Artequakt is detailed and evaluated in this paper
Fifty years of Hoare's Logic
We present a history of Hoare's logic.Comment: 79 pages. To appear in Formal Aspects of Computin
Decoherent Histories and Realism
We reconsider the Decoherent Histories approach to Quantum Mechanics and we
analyze some problems related to its interpretation which, according to us,
have not been adequately clarified by its proponents. We put forward some
assumptions which, in our opinion, are necessary for a realistic interpretation
of the probabilities that the formalism attaches to decoherent histories. We
prove that such assumptions, unless one limits the set of the decoherent
families which can be taken into account, lead to a logical contradiction. The
line of reasoning we will follow is conceptually different from other arguments
which have been presented and which have been rejected by the supporters of the
Decoherent Histories approach. The conclusion is that the Decoherent Histories
approach, to be considered as an interesting realistic alternative to the
orthodox interpretation of Quantum Mechanics, requires the identification of a
mathematically precise criterion to characterize an appropriate set of
decoherent families which does not give rise to any problem.Comment: 34 pages, LaTeX. To appear in Journ. Stat. Phy
Predicting ConceptNet Path Quality Using Crowdsourced Assessments of Naturalness
In many applications, it is important to characterize the way in which two
concepts are semantically related. Knowledge graphs such as ConceptNet provide
a rich source of information for such characterizations by encoding relations
between concepts as edges in a graph. When two concepts are not directly
connected by an edge, their relationship can still be described in terms of the
paths that connect them. Unfortunately, many of these paths are uninformative
and noisy, which means that the success of applications that use such path
features crucially relies on their ability to select high-quality paths. In
existing applications, this path selection process is based on relatively
simple heuristics. In this paper we instead propose to learn to predict path
quality from crowdsourced human assessments. Since we are interested in a
generic task-independent notion of quality, we simply ask human participants to
rank paths according to their subjective assessment of the paths' naturalness,
without attempting to define naturalness or steering the participants towards
particular indicators of quality. We show that a neural network model trained
on these assessments is able to predict human judgments on unseen paths with
near optimal performance. Most notably, we find that the resulting path
selection method is substantially better than the current heuristic approaches
at identifying meaningful paths.Comment: In Proceedings of the Web Conference (WWW) 201
Individual and Domain Adaptation in Sentence Planning for Dialogue
One of the biggest challenges in the development and deployment of spoken
dialogue systems is the design of the spoken language generation module. This
challenge arises from the need for the generator to adapt to many features of
the dialogue domain, user population, and dialogue context. A promising
approach is trainable generation, which uses general-purpose linguistic
knowledge that is automatically adapted to the features of interest, such as
the application domain, individual user, or user group. In this paper we
present and evaluate a trainable sentence planner for providing restaurant
information in the MATCH dialogue system. We show that trainable sentence
planning can produce complex information presentations whose quality is
comparable to the output of a template-based generator tuned to this domain. We
also show that our method easily supports adapting the sentence planner to
individuals, and that the individualized sentence planners generally perform
better than models trained and tested on a population of individuals. Previous
work has documented and utilized individual preferences for content selection,
but to our knowledge, these results provide the first demonstration of
individual preferences for sentence planning operations, affecting the content
order, discourse structure and sentence structure of system responses. Finally,
we evaluate the contribution of different feature sets, and show that, in our
application, n-gram features often do as well as features based on higher-level
linguistic representations
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