scholarly journals Recent Advances in Unification for the EL Family

10.29007/q5px ◽  
2018 ◽  
Author(s):  
Franz Baader ◽  
Stefan Borgwardt ◽  
Barbara Morawska
Keyword(s):  
Description Logics ◽  
General Concept ◽  
Snomed Ct ◽  
Recent Advances ◽  
Unification Algorithms ◽  
New Algorithms

Unification in description logics (DLs) has been proposed as a means to detect redundancies in ontologies. The DL EL, even though quite inexpressive, can be used to formulate large medical ontologies like SNOMED CT. Previously, several unification algorithms for EL were developed that can only deal with acyclic terminologies. In this paper, we give an overview over our recent efforts to generalize these algorithms to allow for general concept inclusions, transitive roles, and role hierarchies. For our new algorithms to be complete, the ontology needs to satisfy a certain cycle restriction.

scholarly journals Hybrid Unification in the Description Logic EL

10.29007/h59c ◽  
2018 ◽  
Author(s):  
Franz Baader ◽  
Oliver Fernandez Gil ◽  
Barbara Morawska
Keyword(s):  
Description Logic ◽  
Description Logics ◽  
General Concept ◽  
Biomedical Ontologies ◽  
Declarative Semantics ◽  
Np Complete ◽  
Unification Algorithms

Unification in Description Logics (DLs) has been proposed as an inferenceservice that can, for example, be used to detect redundancies in ontologies.For the DL EL, which is used to define several largebiomedical ontologies, unification is NP-complete. However, the unification algorithms for EL developeduntil recently could not deal with ontologies containing general concept inclusions (GCIs).In a series of recent papers we have made some progress towards addressing this problem, but the ontologies thedeveloped unification algorithms can deal with need to satisfy a certain cycle restriction.In the present paper, we follow a different approach. Instead of restricting the input ontologies,we generalize the notion of unifiers to so-called hybrid unifiers. Whereas classical unifiers can be viewed as acyclic TBoxes,hybrid unifiers are cyclic TBoxes, which are interpreted together with the ontology of the input using a hybrid semantics thatcombines fixpoint and declarative semantics. We show that hybrid unification in EL is NP-complete

scholarly journals Finding Justifications by Approximating Core for Large-scale Ontologies

2019 ◽  
Author(s):  
Mengyu Gao ◽  
Yuxin Ye ◽  
Dantong Ouyang ◽  
Bin Wang
Keyword(s):  
Local Search ◽  
Real World ◽  
Large Scale ◽  
Description Logics ◽  
Propositional Formula ◽  
Light Weight ◽  
Recent Advances ◽  
New Strategy

Finding justifications for an entailment is one of the major missions in the field of ontology research. Recent advances on finding justifications w.r.t. the light-weight description logics focused on encoding this problem into a propositional formula, and using SAT-based techniques to enumerate all MUSes (minimally unsatisfiable subformulas). It's necessary to import more optimized techniques into finding justifications as emergence of large-scale real-world ontologies. In this paper, we propose a new strategy which introduce local search(in short, LS) technique to compute the approximating core before extracting an exact MUS. Although it is based on a heuristic and LS, such technique is complete in the sense that it always delivers a MUS for any unsatisfiable SAT instance. Our method will find the justifications for large-scale ontologies more effectively.

scholarly journals Matching in the Description Logic FL0 with respect to General TBoxes

10.29007/q74p ◽  
2018 ◽  
Author(s):  
Franz Baader ◽  
Oliver Fernandez Gil ◽  
Pavlos Marantidis
Keyword(s):  
Polynomial Time ◽  
Description Logic ◽  
Description Logics ◽  
General Concept ◽  
Finite Sets ◽  
Matching Algorithm ◽  
Restricted Form ◽  
Matching Concept ◽  
Inference Task

Matching concept descriptions against concept patterns was introduced as a new inference task in Description Logics two decades ago, motivated by applications in the Classic system. Shortly afterwards, a polynomial-time matching algorithm was developed for the DL FL0. However, this algorithm cannot deal with general TBoxes (i.e., finite sets of general concept inclusions). Here we show that matching in FL0 w.r.t. general TBoxes is in ExpTime, which is the best possible complexity for this problem since already subsumption w.r.t. general TBoxes is ExpTime-hard in FL0. We also show that, w.r.t. a restricted form of TBoxes, the complexity of matching in FL0 can be lowered to PSpace.

Recent Advances in High Dispersion Spectroscopy of Globular Cluster Stars

1988 ◽  
Vol 132 ◽  
pp. 525-530
Author(s):  
Raffaele G. Gratton
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Dispersion ◽  
Photographic Material ◽  
Recent Advances ◽  
Metal Abundances ◽  
Ccd Detectors ◽  
Major Progress

The use CCD detectors has allowed a major progress in abundance derivations for globular cluster stars in the last years. Abundances deduced from high dispersion spectra now correlates well with other abundance indicators. I discuss some problems concerning the derivation of accurate metal abundances for globular clusters using high dispersion spectra from both the old photographic and the most recent CCD data. The discrepant low abundances found by Cohen (1980), from photographic material for M71 giants, are found to be due to the use of too high microturbulences.

Fusion and Fission Processes in Exocytosis: Possible Roles for Synexin and Osmotic Lysis in the Two Events

1980 ◽  
Vol 38 ◽  
pp. 594-597
Author(s):  
H.B. Pollard ◽  
C.E. Creutz ◽  
C.J. Pazoles ◽  
J.H. Scott
Keyword(s):  
Small Molecules ◽  
Chromaffin Cells ◽  
Adrenal Glands ◽  
General Concept ◽  
Extracellular Calcium ◽  
Large Protein ◽  
Granule Membrane ◽  
Osmotic Lysis ◽  
Per Se ◽  
Chemical Evidence

Exocytosis is a general concept describing secretion of enzymes, hormones and transmitters that are otherwise sequestered in intracellular granules. Chemical evidence for this concept was first gathered from studies on chromaffin cells in perfused adrenal glands, in which it was found that granule contents, including both large protein and small molecules such as adrenaline and ATP, were released together while the granule membrane was retained in the cell. A number of exhaustive reviews of this early work have been published and are summarized in Reference 1. The critical experiments demonstrating the importance of extracellular calcium for exocytosis per se were also first performed in this system (2,3), further indicating the substantial service given by chromaffin cells to those interested in secretory phenomena over the years.

Chelation-assisted transition metal-catalysed C–H chalcogenylations

2020 ◽  
Vol 7 (8) ◽  
pp. 1022-1060 ◽  
Author(s):  
Wenbo Ma ◽  
Nikolaos Kaplaneris ◽  
Xinyue Fang ◽  
Linghui Gu ◽  
Ruhuai Mei ◽  
...  
Keyword(s):  
Transition Metal ◽  
Recent Advances ◽  
Site Selectivity ◽  
Transition Metal Catalyzed ◽  
Metal Catalyzed

This review summarizes recent advances in C–S and C–Se formations via transition metal-catalyzed C–H functionalization utilizing directing groups to control the site-selectivity.

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