Papers by Luciano Serafini
Semantic Web, 2021
A knowledge graph (KG) represents real-world entities and their relationships. The represented kn... more A knowledge graph (KG) represents real-world entities and their relationships. The represented knowledge is often context-dependent, leading to the construction of contextualized KGs. The multidimensional and hierarchical nature of context invites comparison with the OLAP cube model from multidimensional data analysis. Traditional systems for online analytical processing (OLAP) employ multidimensional models to represent numeric values for further analysis using dedicated query operations. In this paper, along with an adaptation of the OLAP cube model for KGs, we introduce an adaptation of the traditional OLAP query operations for the purposes of performing analysis over KGs. In particular, we decompose the roll-up operation from traditional OLAP into a merge and an abstraction operation. The merge operation corresponds to the selection of knowledge from different contexts whereas abstraction replaces entities with more general entities. The result of such a query is a more abstract...
As the amount of available linked data expand and the number of related applications increases, t... more As the amount of available linked data expand and the number of related applications increases, the management of aspects such as provenance and access control of such data begin to become an issue. Current approaches do not provide sufficient support for automatic reasoning over different metadata types and their possible interdependencies. MetaReasons is a framework that supports representation and automated reasoning over metadata in a single logical formalism. Different types of metadata, like data-provenance and accessibility-restrictions, are represented as distinct meta-theories and dependencies between metadata types are represented by rules between different meta-theories. In this paper we present the definition of the MetaReasons framework and two examples meta-theories for provenance and access control. Moreover, we propose a materialization calculus for forward reasoning on the two aspects.
Theory and Practice of Logic Programming, 2021
Reasoning on defeasible knowledge is a topic of interest in the area of description logics, as it... more Reasoning on defeasible knowledge is a topic of interest in the area of description logics, as it is related to the need of representing exceptional instances in knowledge bases. In this direction, in our previous works we presented a framework for representing (contextualized) OWL RL knowledge bases with a notion of justified exceptions on defeasible axioms: reasoning in such framework is realized by a translation into ASP programs. The resulting reasoning process for OWL RL, however, introduces a complex encoding in order to capture reasoning on the negative information needed for reasoning on exceptions. In this paper, we apply the justified exception approach to knowledge bases in , that is, the language underlying OWL QL. We provide a definition for knowledge bases with defeasible axioms and study their semantic and computational properties. In particular, we study the effects of exceptions over unnamed individuals. The limited form of axioms allows us to formulate a simpler AS...
Comparing contextual and flat representations ofknowledge
Proceedings of the seventh international conference on Knowledge capture, 2013
ABSTRACT The capability of dealing with context sensitive knowledge is recognized as a crucial as... more ABSTRACT The capability of dealing with context sensitive knowledge is recognized as a crucial aspect in the management of massive amounts of Semantic Web (SW) data. Contextual knowledge can be modelled either by adopting the primitives from RDF/OWL based SW languages or by extending such languages with new specific constructs for context representation. In this paper, we show the benefits of the context-based solution by comparing modelling and reasoning in the two approaches on the paradigmatic use case of FIFA World Cup. The comparison considers the three key aspects of engineering and exploiting knowledge: (i) simplicity and expressivity of the (formal) language; (ii) compactness of the representation; and (iii) efficiency of reasoning. As for (i), we show that the context-based language enables the construction of simpler and more intuitive models while the RDF/OWL "flat" model presents practical limitations in modelling cross-contextual knowledge. For (ii), we show that the contextualized model is more compact than the OWL based model. Finally for (iii), query answering in the context-based model outperforms in most of the cases performances on the flat model.
Lecture Notes in Computer Science, 2015
As the interest in the representation of context dependent knowledge in the Semantic Web has been... more As the interest in the representation of context dependent knowledge in the Semantic Web has been recognized, a number of logic based solutions have been proposed in this regard. In our recent works, in response to this need, we presented the description logic-based Contextualized Knowledge Repository (CKR) framework. CKR is not only a theoretical framework, but it has been effectively implemented over state-of-the-art tools for the management of Semantic Web data: inference inside and across contexts has been realized in the form of forward SPARQL-based rules over different RDF named graphs. In this paper we present the first evaluation results for such CKR implementation. In particular, in first experiment we study its scalability with respect to different reasoning regimes. In a second experiment we analyze the effects of knowledge propagation on the computation of inferences.
Recently, representation of context dependent knowledge in the Semantic Web has been recognized a... more Recently, representation of context dependent knowledge in the Semantic Web has been recognized as a relevant issue and a number of logic based solutions have been proposed in this regard: among them, in our previous works we presented the Contextualized Knowledge Repository (CKR) framework. A CKR knowledge base has a two layered structure, modelled by a global context and a set of local contexts: the global context not only contains the metaknowledge defining the properties of local contexts, but also holds the global (context independent) object knowledge that is shared by all of the local contexts. In many practical cases, however, it is desirable to leave the possibility to "override" the global object knowledge at the local level, by recognizing the axioms that can allow exceptional instances in the local contexts. This clearly requires to add a notion of non monotonicity across the global and the local parts of a CKR. In this paper we present an extension to the semantics of CKR to introduce such notion of defeasible axioms. By extending a previously proposed datalog translation, we obtain a representation for CKR as a datalog program with negation under answer set semantics. This representation can be exploited as the basis for implementation of query answering for the proposed extension of CKR. This paper has been previously presented at the 5th International Workshop on Acquisition, Representation and Reasoning with Contextualized Knowledge (ARCOE-LogIC 2013). G : { D(Cheap Interesting), Cheap(fbmatch), Cheap(market), mod(cultural tourist, ctourist m) }, K ctourist m : { ¬Interesting(fbmatch) }. Note that the negative assertion in the local context represents, as discussed in Example 2, an exception to the defeasible axiom: we want to recognize this "overriding" for the fbmatch instance, but still apply the defeasible inclusion for market. 3 3 http://www.investintrentino.it/News/Trentour-Trentinoplatform-for-smart-tourism 4 To keep things simple, we omit modeling sportive events by a separate concept.
Towards content-oriented patent document processing: Intelligent patent analysis and summarization
World Patent Information, 2015
Abstract In this article, we present an operational prototype of a workbench for intelligent pate... more Abstract In this article, we present an operational prototype of a workbench for intelligent patent document analysis and summarization that has been developed in the context of the R&D project TOPAS, partially funded by the European Commission. The workbench uses the GATE environment as infrastructure for document representation and algorithm integration. It contains, apart from several preprocessing tools, five modules for the individual aspects of patent analysis (entity recognition, lexical chain identification, invention composition derivation, segmentation, and claim – description alignment) and a module for patent summarization. The workbench, which has been tested in different application settings, can be used as a standalone engine or as component within a more global patent processing line. Most of its modules can be also used separately.
Citizens are increasingly aware of the influence of environmental and meteorological conditions o... more Citizens are increasingly aware of the influence of environmental and meteorological conditions on the quality of their life. This results in an increasing demand for personalized environmental information, i.e., information that is tailored to citizens' specific context and background. In this work we describe the development of an environmental information system that addresses this demand in its full complexity. Specifically, we aim at developing a system that supports submission of user generated queries related to environmental conditions. From the technical point of view, the system is tuned to discover reliable data in the web and to process these data in order to convert them into knowledge, which is stored in a dedicated repository. At run time, this information is transferred into an ontology-structured knowledge base, from which then information relevant to the specific user is deduced and communicated in the language of their preference.
Environmental and meteorological conditions are of utmost importance for the population, as they ... more Environmental and meteorological conditions are of utmost importance for the population, as they are strongly related to the quality of life. Citizens are increasingly aware of this importance. This awareness results in an increasing demand for environmental information tailored to their specific needs and background. We present an environmental information platform that supports submission of user queries related to environmental conditions and orchestrates results from complementary services to generate personalized suggestions. From the technical viewpoint, the system discovers and processes reliable data in the web in order to convert them into knowledge. At run time, this information is transferred into an ontology-structured knowledge base, from which then information relevant to the specific user is deduced and communicated in the language of their preference. The platform is demonstrated with real world use cases in the south area of Finland showing the impact it can have on the quality of everyday life.
ExpTime Tableaux Algorithm for Contextualized $\mathcal{ALC}$
Lecture Notes in Computer Science, 2013
Contextualized Knowledge Repository CKR is a DL-based framework for representation and reasoning ... more Contextualized Knowledge Repository CKR is a DL-based framework for representation and reasoning with context dependent knowledge. It addresses the widely recognized need for contextualization of the Semantic Web data sources. Reasoning with CKR is possible thanks to a reduction to standard DL, and more recently a NExpTime tableaux algorithm was introduced for $\mathcal{ALC}$ -based CKR. In this paper we present an ExpTime tableaux algorithm for $\mathcal{ALC}$ -based CKR. The algorithm not only formally defines a tableaux decision procedure with optimal complexity, it is also presented in a form that can be effectively applied in practice employing a suitable rule application strategy together with node caching.
Lecture Notes in Computer Science, 2011
The dematerialization of documents produced within the Public Administration (PA) represents a ke... more The dematerialization of documents produced within the Public Administration (PA) represents a key contribution that Information and Communication Technology can provide towards the modernization of services within the PA. The availability of proper and precise models of the administrative procedures, and of the specific "entities" related to these procedures, such as the documents involved in the procedures or the organizational roles performing the activities, is an important step towards both (1) the replacement of paper-based procedures with electronic-based ones, and (2) the definition of guidelines and functions needed to safely store, catalogue, manage and retrieve in an appropriate archival system the electronic documents produced within the PA. In this paper we report the experience of customizing a semantic wiki based tool (MoKi) for the modeling of administrative procedures (processes) and their related "entities" (ontologies). The tool has been used and evaluated by several domain experts from different Italian regions in the context of a national project. This experience, and the reported evaluation, highlight the potential and criticality of using semantic wiki-based tools for the modeling of complex domains composed of processes and ontologies in a real setting.
Model checking is a very successful technique which has been applied in the design and veriicatio... more Model checking is a very successful technique which has been applied in the design and veriication of nite state concurrent reactive processes. In this paper we show how this technique can be lifted to be applicable to multiagent systems. Our approach allows us to reuse the technology and tools developed in model checking, to design and verify multiagent systems in a modular and incremental way, and also to have a very eecient model checking algorithm.
The dematerialization of documents produced within the Public Administration (PA) represents a ke... more The dematerialization of documents produced within the Public Administration (PA) represents a key contribution that Information and Communication Technology can provide towards the modernization of services within the PA. The availability of proper and precise models of the administrative procedures, and of the specific "entities" related to these procedures, such as the documents involved in the procedures or the organizational roles performing the activities, is an important step towards both (1) the replacement of paper-based procedures with electronic-based ones, and (2) the definition of guidelines and functions needed to safely store, catalogue, manage and retrieve in an appropriate archival system the electronic documents produced within the PA. In this paper we report the experience of customizing a semantic wiki based tool (MoKi) for the modeling of administrative procedures (processes) and their related "entities" (ontologies). The tool has been used and evaluated by several domain experts from different Italian regions in the context of a national project. This experience, and the reported evaluation, highlight the potential and criticality of using semantic wiki-based tools for the modeling of complex domains composed of processes and ontologies in a real setting.
Lecture Notes in Computer Science, 2011
The dematerialization of documents produced within the Public Administration (PA) represents a ke... more The dematerialization of documents produced within the Public Administration (PA) represents a key contribution that Information and Communication Technology can provide towards the modernization of services within the PA. The availability of proper and precise models of the administrative procedures, and of the specific "entities" related to these procedures, such as the documents involved in the procedures or the organizational roles performing the activities, is an important step towards both (1) the replacement of paper-based procedures with electronic-based ones, and (2) the definition of guidelines and functions needed to safely store, catalogue, manage and retrieve in an appropriate archival system the electronic documents produced within the PA. In this paper we report the experience of customizing a semantic wiki based tool (MoKi) for the modeling of administrative procedures (processes) and their related "entities" (ontologies). The tool has been used and evaluated by several domain experts from different Italian regions in the context of a national project. This experience, and the reported evaluation, highlight the potential and criticality of using semantic wiki-based tools for the modeling of complex domains composed of processes and ontologies in a real setting.
World Patent Information, 2008
In this article, we present ongoing work on an advanced patent processing service PATExpert. The ... more In this article, we present ongoing work on an advanced patent processing service PATExpert. The central assumption underlying PATExpert is that in order to meet the needs of the users of patent processing services, recourse must be made to the content of patent material. We introduce a content representation schema for patent documentation and sketch the design of techniques that facilitate the integration of this schema into the patent processing cycle. Two types of techniques are discussed. Techniques of the first type facilitate the access to the content of patent documentation provided in a textual format -be it by the human reader or by the machine -in that they rephrase and summarize the documentation and map it onto a formal semantic representation. Techniques of the second type operate on the content representation. At this stage, PATExpert is explored in two technology areas -optical recording devices and machine tools. The work is being carried out in the framework of an R&D-project partially funded by the European Commission.
European Journal of Operational Research, 1987
+ 334 pages, £22.50 According to the Preface, this Proceedings includes all the refereed papers w... more + 334 pages, £22.50 According to the Preface, this Proceedings includes all the refereed papers which were presented at the conference and the invited papers by Austin Tate and Abe Mamdani. With respect to the readership of EJOR, several of the papers present material on topics that operational research workers also investigate but by using perhaps more formally mathematical, less ad hoc problem solving and decision making approaches. In fact, there is a growing trend among expert systems specialists to investigate representations of deep knowledge (as is done in a paper by A.G. Cohn) in order to enhance the flexibility of the resulting expert system. This suggests that the formal integration of current expert systems concepts with mathematical models for problem solving (e.g., operational research tools) may not be far away, which should be of particular interest to a large portion of the EJOR readership. One specific OR tool deserves mention here: multiattribute utility theory (MAUT). A portion of the Expert System/OR community is currently active in investigating how expert systems can be integrated with MAUT in order to develop systems sufficiently robust and sensitive to user (rather than expert) values and goals. A related discussion can be found in A. Sloman's paper on real-time multiple-motive expert systems.
As the amount of available linked data expand and the
number of related applications increases, t... more As the amount of available linked data expand and the
number of related applications increases, the management of aspects
such as provenance and access control of such data begin to become
an issue. Current approaches do not provide sufficient support for
automatic reasoning over different metadata and their possible interdependencies.
MetaReasons is a framework that supports the representation
of metadata in a logical formalism and consequently to
support automated reasoning on metadata. Different types of metadata,
such as data-provenance and accessibility-restrictions are represented
as distinct meta-theories, and dependencies between types
of metadata are represented by rules between different meta-theories.
In this paper we present the logic based definition of the MetaReasons
framework and two examples of meta-theories for provenance
and access control. Moreover, we propose a materialization calculus
for concrete forward reasoning on the two aspects.
We investigate a formalism for reasoning with multiple local ontologies, connected by directional... more We investigate a formalism for reasoning with multiple local ontologies, connected by directional semantic mappings. We propose: (1) a relatively small change of semantics which localizes inconsistency (thereby making unnecessary global satisfiability checks), and preserves directionality of "knowledge import"; (2) a characterization of inferences using a fixed-point operator, which can form the basis of a cache-based implementation for local reasoners; (3) a truly distributed tableaux algorithm for cases when the local reasoners use subsets of SHIQ. Throughout, we indicate the applicability of the results to several recent proposals for knowledge representation and reasoning that support modularity, scalability and distributed reasoning. We assume the reader is familiar with description logics and related reasoning systems, as described in .
Uploads
Papers by Luciano Serafini
number of related applications increases, the management of aspects
such as provenance and access control of such data begin to become
an issue. Current approaches do not provide sufficient support for
automatic reasoning over different metadata and their possible interdependencies.
MetaReasons is a framework that supports the representation
of metadata in a logical formalism and consequently to
support automated reasoning on metadata. Different types of metadata,
such as data-provenance and accessibility-restrictions are represented
as distinct meta-theories, and dependencies between types
of metadata are represented by rules between different meta-theories.
In this paper we present the logic based definition of the MetaReasons
framework and two examples of meta-theories for provenance
and access control. Moreover, we propose a materialization calculus
for concrete forward reasoning on the two aspects.
number of related applications increases, the management of aspects
such as provenance and access control of such data begin to become
an issue. Current approaches do not provide sufficient support for
automatic reasoning over different metadata and their possible interdependencies.
MetaReasons is a framework that supports the representation
of metadata in a logical formalism and consequently to
support automated reasoning on metadata. Different types of metadata,
such as data-provenance and accessibility-restrictions are represented
as distinct meta-theories, and dependencies between types
of metadata are represented by rules between different meta-theories.
In this paper we present the logic based definition of the MetaReasons
framework and two examples of meta-theories for provenance
and access control. Moreover, we propose a materialization calculus
for concrete forward reasoning on the two aspects.