On Disallowing Punctual Intervals in Reflexive Semantics of Halpern-Shoham Logic

Mapping Intimacies ◽

10.29007/fl6v ◽

2018 ◽

Author(s):

Przemysław Andrzej Wałęga

Keyword(s):

Computational Complexity ◽

Expressive Power ◽

Temporal Reasoning ◽

Satisfiability Problem ◽

Time Points ◽

Modal Operators ◽

The Core ◽

Core Fragment ◽

Horn Fragment

Halpern-Shoham logic (HS) is a very expressive and elegant formalism for interval temporal reasoning in which the satisfiability problem is undecidable. One of the methods to obtain HS-fragments of lower computational complexity is to adopt the softened (reflexive) seman- tics of the accessibility relations. In the paper we consider disallowing punctual intervals in reflexive semantics. We show that in this case we gain additional expressive power, which over discrete orders of time points results in PSpace-hardness of the Horn fragment of HS without diamond modal operators is and in undecidability of the core fragment of HS.

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Searching for Well-Behaved Fragments of Halpern-Shoham Logic

Proceedings of the Twenty-Sixth International Joint Conference on Artificial Intelligence ◽

10.24963/ijcai.2017/769 ◽

2017 ◽

Author(s):

Przemysław Andrzej Wałęga

Keyword(s):

Artificial Intelligence ◽

Computational Complexity ◽

Natural Language ◽

Real Time ◽

Temporal Reasoning ◽

Time Intervals ◽

Practical Applications ◽

Time Points ◽

Language Analysis ◽

Natural Language Analysis

Temporal reasoning constitutes one of the main topics within the field of Artificial Intelligence. Particularly interesting are interval-based methods, in which time intervals are treated as basic ontological objects, in opposite to point-based methods, where time-points are considered as basic. The former approach is more expressive and seems to be more appropriate for such applications as natural language analysis or real time processes verification. My research concerns the classical interval-based logic, namely Halpern-Shoham logic (HS). In particular, my investigation continues recently proposed search for well-behaved - i.e., expressive enough for practical applications and of low computational complexity - HS fragments obtained by imposing syntactical restrictions on the usage of propositional connectives in their languages.

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Computational complexity of relating time points with intervals

Artificial Intelligence ◽

10.1016/s0004-3702(99)00007-7 ◽

1999 ◽

Vol 109 (1-2) ◽

pp. 273-295 ◽

Cited By ~ 17

Author(s):

Peter Jonsson ◽

Thomas Drakengren ◽

Christer Bäckström

Keyword(s):

Computational Complexity ◽

Time Points

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The Design and Experimental Analysis of Algorithms for Temporal Reasoning

Journal of Artificial Intelligence Research ◽

10.1613/jair.232 ◽

1996 ◽

Vol 4 ◽

pp. 1-18 ◽

Cited By ~ 49

Author(s):

P. Van Beek ◽

D. W. Manchak

Keyword(s):

Analysis Of Algorithms ◽

Temporal Reasoning ◽

Temporal Information ◽

Search Problem ◽

Planning And Scheduling ◽

Backtracking Search ◽

The Core ◽

Reasoning System ◽

Space Requirements ◽

Experimental Analysis Of Algorithms

Many applications -- from planning and scheduling to problems in molecular biology -- rely heavily on a temporal reasoning component. In this paper, we discuss the design and empirical analysis of algorithms for a temporal reasoning system based on Allen's influential interval-based framework for representing temporal information. At the core of the system are algorithms for determining whether the temporal information is consistent, and, if so, finding one or more scenarios that are consistent with the temporal information. Two important algorithms for these tasks are a path consistency algorithm and a backtracking algorithm. For the path consistency algorithm, we develop techniques that can result in up to a ten-fold speedup over an already highly optimized implementation. For the backtracking algorithm, we develop variable and value ordering heuristics that are shown empirically to dramatically improve the performance of the algorithm. As well, we show that a previously suggested reformulation of the backtracking search problem can reduce the time and space requirements of the backtracking search. Taken together, the techniques we develop allow a temporal reasoning component to solve problems that are of practical size.

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A Review of Fuzzy Models for the Semantic Web

Web Technologies ◽

10.4018/978-1-60566-982-3.ch005 ◽

2011 ◽

pp. 63-77

Author(s):

Hailong Wang ◽

Zongmin Ma ◽

Li Yan ◽

Jingwei Cheng

Keyword(s):

Computational Complexity ◽

Semantic Web ◽

Set Theory ◽

Fuzzy Set ◽

Fuzzy Set Theory ◽

Description Logics ◽

Expressive Power ◽

Semantic Knowledge ◽

Context Information ◽

Semantic Knowledge Base

In the Semantic Web context, information would be retrieved, processed, shared, reused and aligned in the maximum automatic way possible. Our experience with such applications in the Semantic Web has shown that these are rarely a matter of true or false but rather procedures that require degrees of relatedness, similarity, or ranking. Apart from the wealth of applications that are inherently imprecise, information itself is many times imprecise or vague. In order to be able to represent and reason with such type of information in the Semantic Web, different general approaches for extending semantic web languages with the ability to represent imprecision and uncertainty has been explored. In this chapter, we focus our attention on fuzzy extension approaches which are based on fuzzy set theory. We review the existing proposals for extending the theoretical counterpart of the semantic web languages, description logics (DLs), and the languages themselves. The following statements will include the expressive power of the fuzzy DLs formalism and its syntax and semantic, knowledge base, the decidability of the tableaux algorithm and its computational complexity etc. Also the fuzzy extension to OWL is discussed in this chapter.

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Dealing with Precise and Imprecise Temporal Data in Crisp Ontology

International Journal of Information Technology and Web Engineering ◽

10.4018/ijitwe.2020040102 ◽

2020 ◽

Vol 15 (2) ◽

pp. 30-49 ◽

Cited By ~ 1

Author(s):

Fatma Ghorbel ◽

Fayçal Hamdi ◽

Elisabeth Métais

Keyword(s):

Set Theory ◽

Temporal Reasoning ◽

Time Interval ◽

Temporal Data ◽

Time Intervals ◽

Time Points ◽

Interval Algebra ◽

Precise Time ◽

Time Point

This article proposes a crisp-based approach for representing and reasoning about concepts evolving in time and of their properties in terms of qualitative relations (e.g., “before”) in addition to quantitative ones, time intervals and points. It is not only suitable to handle precise time intervals and points, but also imprecise ones. It extends the 4D-fluents approach with crisp components to represent handed data. It also extends the Allen's interval algebra. This extension allows reasoning about imprecise time intervals. Compared to related work, it is based on crisp set theory. These relations preserve many properties of the original algebra. Their definitions are adapted to allow relating a time interval and a time point, and two time points. All relations can be used for temporal reasoning by means of transitivity tables. Finally, it proposes a crisp ontology that based on the extended Allen's algebra instantiates the 4D-fluents-based representation.

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THE USE OF CARIN LANGUAGE AND ALGORITHMS FOR INFORMATION INTEGRATION: THE PICSEL SYSTEM

International Journal of Cooperative Information Systems ◽

10.1142/s0218843000000181 ◽

2000 ◽

Vol 09 (04) ◽

pp. 383-401 ◽

Cited By ~ 54

Author(s):

FRANÇOIS GOASDOUÉ ◽

VÉRONIQUE LATTÈS ◽

MARIE-CHRISTINE ROUSSET

Keyword(s):

Information Integration ◽

Information Sources ◽

Expressive Power ◽

Real Case ◽

Travel Agency ◽

Integration System ◽

The Core ◽

Knowledge Based ◽

Information Server ◽

Logical Formalism

PICSEL is an information integration system over sources that are distributed and possibly heterogeneous. The approach which has been chosen in PICSEL is to define an information server as a knowledge-based mediator in which CARIN is used as the core logical formalism to represent both the domain of application and the contents of information sources relevant to that domain. In this paper, we describe the way the expressive power of the CARIN language is exploited in the PICSEL information integration system, while maintaining the decidability of query answering. We illustrate it on examples coming from the tourism domain, which is the first real case that we have to consider in PICSEL, in collaboration with the travel agency Degriftour. see

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The power of modal separation logics

Journal of Logic and Computation ◽

10.1093/logcom/exz019 ◽

2019 ◽

Vol 29 (8) ◽

pp. 1139-1184 ◽

Cited By ~ 1

Author(s):

Stéphane Demri ◽

Raul Fervari

Keyword(s):

Separation Logic ◽

Satisfiability Problem ◽

Alternative Semantics ◽

Temporal Logics ◽

Original Language ◽

Modal Operators ◽

Logical Connectives ◽

Np Complete ◽

Memory States ◽

The Difference

Abstract We introduce a modal separation logic MSL whose models are memory states from separation logic and the logical connectives include modal operators as well as separating conjunction and implication from separation logic. With such a combination of operators, some fragments of MSL can be seen as genuine modal logics whereas some others capture standard separation logics, leading to an original language to speak about memory states. We analyse the decidability status and the computational complexity of several fragments of MSL, obtaining surprising results by design of proof methods that take into account the modal and separation features of MSL. For example, the satisfiability problem for the fragment of MSL with $\Diamond $, the difference modality $\langle \neq \rangle $ and separating conjunction $\ast $ is shown Tower-complete whereas the restriction either to $\Diamond $ and $\ast $ or to $\langle \neq \rangle $ and $\ast $ is only NP-complete. We establish that the full logic MSL admits an undecidable satisfiability problem. Furthermore, we investigate variants of MSL with alternative semantics and we build bridges with interval temporal logics and with logics equipped with sabotage operators.

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False-Negative Results in Point-of-Care Qualitative Human Chorionic Gonadotropin (hCG) Devices Due to Excess hCGβ Core Fragment

Clinical Chemistry ◽

10.1373/clinchem.2008.121210 ◽

2009 ◽

Vol 55 (7) ◽

pp. 1389-1394 ◽

Cited By ~ 46

Author(s):

Ann M Gronowski ◽

Mark Cervinski ◽

Ulf-Håkan Stenman ◽

Alison Woodworth ◽

Lori Ashby ◽

...

Keyword(s):

Chorionic Gonadotropin ◽

Human Chorionic Gonadotropin ◽

Point Of Care ◽

False Negative ◽

The Core ◽

Core Fragment ◽

Negative Results ◽

False Negative Results ◽

Positive Results ◽

Urine Specimens

Abstract Background: During pregnancy, human chorionic gonadotropin (hCG) immunoreactivity in urine consists of intact hCG as well as a number of hCG variants including the core fragment of hCGβ (hCGβcf). We identified 3 urine specimens with apparent false-negative results using the OSOM® hCG Combo Test (Genzyme Diagnostics) qualitative hCG device and sought to determine whether an excess of 1 of the fragments or variants might be the cause of the interference. Methods: We measured concentrations of hCG variants in the urine from 3 patients with apparent false-negative hCG results. Purified hCG variants were added to urines positive for hCG and tested using the OSOM, ICON® 25 hCG (Beckman Coulter), and hCG Combo SP® Brand (Cardinal Health) devices. Results: Dilution of these 3 urine samples resulted in positive results on the OSOM device. Quantification of hCG variants in each of the 3 patient urine specimens demonstrated that hCGβcf occurred in molar excess of intact hCG. Addition of purified hCGβcf to hCG-positive urines caused false-negative hCG results using the OSOM and ICON qualitative urine hCG devices. Conclusions: Increased concentrations of hCGβcf can cause false-negative results on the OSOM and ICON qualitative urine hCG devices. .

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