Maurizio Lenzerini

Maurizio Lenzerini
Sapienza University of Rome | la sapienza · Department of Computer, Automatic and Management Engineering "Antonio Ruberti"

Laurea ingegneria elettronica

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414
Publications
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21,419
Citations
Citations since 2016
28 Research Items
3955 Citations
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600

Publications

Publications (414)
Article
In Ontology-Based Data Management (OBDM), an abstraction of a source query q is a query over the ontology capturing the semantics of q in terms of the concepts and the relations available in the ontology. Since a perfect characterization of a source query may not exist, the notions of best sound and complete approximations of an abstraction have be...
Preprint
Full-text available
The Associazione Medici Diabetologi (AMD) collects and manages one of the largest worldwide-available collections of diabetic patient records, also known as the AMD database. This paper presents the initial results of an ongoing project whose focus is the application of Artificial Intelligence and Machine Learning techniques for conceptualizing, cl...
Article
A data ecosystem (DE) offers a keystone-player or alliance-driven infrastructure that enables the interaction of different stakeholders and the resolution of interoperability issues among shared data. However, despite years of research in data governance and management, trustability is still affected by the absence of transparent and traceable data...
Article
In this paper we introduce the notion of mapping-based knowledge base (MKB) to formalize the situation where both the extensional and the intensional level of the ontology are determined by suitable mappings to a set of (relational) data sources. This allows for making the intensional level of the ontology as dynamic as traditionally the extensiona...
Preprint
Full-text available
Given an input dataset (i.e., a set of tuples), query definability in Ontology-based Data Management (OBDM) amounts to find a query over the ontology whose certain answers coincide with the tuples in the given dataset. We refer to such a query as a characterization of the dataset with respect to the OBDM system. Our first contribution is to propose...
Conference Paper
The use of virtual collections of data is often essential in several data and knowledge management tasks. In the literature, the standard way to define virtual data collections is via views, i.e., virtual relations defined using queries. In data and knowledge bases, the notion of views is a staple of data access, data integration and exchange, quer...
Preprint
Full-text available
A Data Ecosystem offers a keystone-player or alliance-driven infrastructure that enables the interaction of different stakeholders and the resolution of interoperability issues among shared data. However, despite years of research in data governance and management, trustability is still affected by the absence of transparent and traceable data-driv...
Chapter
Distributed information systems and applications are generally described in terms of components and interfaces among them. How these component-based architectures have been designed and implemented evolved over the years, giving rise to the so-called paradigm of Service-Oriented Computing (SOC). In this chapter, we will follow a 25-years-long journ...
Article
OWL 2 QL is a standard profile of the OWL 2 ontology language, specifically tailored to Ontology-Based Data Management. Inspired by recent work on higher-order Description Logics, in this paper we present a new semantics for OWL 2 QL ontologies, called Metamodeling Semantics (MS), and show that, in contrast to the official Direct Semantics (DS) for...
Article
Full-text available
The quantitative evaluation of research is currently carried out by means of indicators calculated on data extracted and integrated by analysts who elaborate them by creating illustrative tables and plots of results. In this approach, the robustness of the metrics used and the possibility for users of the metrics to intervene in the evaluation proc...
Conference Paper
In Ontology-Based Data Access (OBDA), a domain ontology is linked to the data sources of an organization in order to query, integrate and manage data through the concepts and relations of the domain of interest, thus abstracting from the technical details of the data layer implementation. While the great majority of contributions in OBDA in the las...
Article
Ontology-based data management (OBDM) is a powerful knowledge-oriented paradigm for managing data spread over multiple heterogeneous sources. In OBDM, the data sources of an information system are handled through the reconciled view provided by an ontology, i.e., the conceptualization of the underlying domain of interest expressed in some formal la...
Article
In the context of the Description Logic DL-Liteℛ≠, i.e., DL-Liteℛ without UNA and with inequality axioms, we address the problem of adding to unions of conjunctive queries (UCQs) one of the simplest forms of negation, namely, inequality. It is well known that answering conjunctive queries with unrestricted inequalities over DL-Liteℛ ontologies is i...
Conference Paper
Full-text available
We study the problem of associating formal semantic descriptions to data services. We base our proposal on the Ontology-based Data Access paradigm, where a domain ontology is used to provide a semantic layer mapped to the data sources of an organization. The basic idea is to explain the semantics of a data service in terms of a query over the ontol...
Chapter
The issue of cooperation, integration, and coordination between information peers has been addressed over the years both in the context of the Semantic Web and in several other networked environments, including data integration, Peer-to-Peer and Grid computing, service-oriented computing, distributed agent systems, and collaborative data sharing. O...
Chapter
Full-text available
Data interoperability refers to the issue of accessing and processing data from multiple sources in order to create more holistic and contextual information for improving data analysis, for better decision-making, and for accountability purposes. In the era towards a data-driven society, the notion of data interoperability is of paramount importanc...
Article
While the amount of data stored in current information systems continuously grows, and the processes making use of such data become more and more complex, extracting knowledge and getting insights from these data, as well as governing both data and the associated processes, are still challenging tasks. The problem is complicated by the proliferatio...
Article
Full-text available
Ontology-based data management (OBDM) is a recent paradigm for addressing data management based on a conceptualization of the domain of interest, called ontology. A system realizing the vision of OBDM is constituted by three layers: the ontology, that provides a high level, formal, logic-based representation of the above mentioned conceptualization...
Chapter
Full-text available
While big data analytics is considered as one of the most important paths to competitive advantage of today’s enterprises, data scientists spend a comparatively large amount of time in the data preparation and data integration phase of a big data project. This shows that data integration is still a major challenge in IT applications. Over the past...
Article
Metamodeling and metaquerying are gaining momentum in the context of both conceptual modeling and semantic web. Indeed it has been largely recognized that metamodeling represents a very useful tool to formalize complex patterns involving elements of the domain of interest, that otherwise are forced to be excluded from the modeling process, and a nu...
Conference Paper
After years of focus on technologies for big data storing and processing, many observers are pointing out that making sense of big data cannot be done without suitable tools for conceptualizing, preparing, and integrating data (see http://www.dbta.com/). Research in the last years has shown that taking into account the semantics of data is crucial...
Conference Paper
OWL 2 QL is the profile of OWL 2 targeted to Ontology-Based Data Access (OBDA) scenarios, where large amount of data are to be accessed, and thus answering conjunctive queries over data is the main task. However, this task is quite restrained wrt the classical KR Ask-and-Tell framework based on querying the whole theory, not only facts (data). If w...
Article
We illustrate the usefulness of an Ontology-Based Data Management (OBDM) approach to develop an open information system, allowing for a deep level of interoperability among different databases, and accounting for additional dimensions of data quality compared to the standard dimensions of the OECD (Quality framework and guidelines for OECD statisti...
Article
Full-text available
This paper proposes an Ontology-Based Data Management (OBDM) approach to coordinate, integrate and maintain the data needed for Science, Technology and Innovation (STI) policy development. The OBDM approach is a form of integration of information in which the global schema of data is substituted by the conceptual model of the domain, formally speci...
Article
The Encyclopedia of DNA Elements (ENCODE) is a huge and still expanding public repository of more than 4,000 experiments and 25,000 data files, assembled by a large international consortium since 2007; unknown biological knowledge can be extracted from these huge and largely unexplored data, leading to data-driven genomic, transcriptomic and epigen...
Article
Ontology-based data access (OBDA) is receiving great attention as a new paradigm for managing information systems through semantic technologies. According to this paradigm, a Description Logic ontology provides an abstract and formal representation of the domain of interest to the information system, and is used as a sophisticated schema for access...
Conference Paper
Hi(DL − Lite R ) is a higher-order Description Logic obtained from DL − Lite R by adding metamodeling features, and is equipped with a query language that is able to express higher-order queries. We investigate the problem of answering a particular class of such queries, called instance higher-order queries, posed over Hi(DL − Lite R ) knowledge ba...
Article
Ontology-based data access (OBDA) is a new paradigm aiming at accessing and managing data by means of an ontology, i.e., a conceptual representation of the domain of interest in the underlying information system. In the last years, this new paradigm has been used for providing users with ab-stract (independent from technological and system-oriented...
Article
Ontology-based data access (OBDA) is a new paradigm aiming at accessing and managing data by means of an ontology, i.e., a conceptual representation of the domain of interest in the underlying information system. In the last years, this new paradigm has been used for providing users with suitable mechanisms for querying the data residing at the inf...
Article
In this paper we present an ontology-based data management (OBDM) project concerning the Italian public debt domain, carried out within a joint collaboration between Sapienza University of Rome and the Department of Treasury of the Italian Ministry of Economy and Finance. We discuss the motivations at the basis of this project and present the main...
Chapter
Full-text available
This chapter proposes steps towards the solution to the data access problem that end-users typically face when dealing with Big Data.
Article
A schema mapping is a formal specification of the relationship holding between the databases conforming to two given schemas, called source and target, respectively. While in the general case a schema mapping is specified in terms of assertions relating two queries in some given language, various simplified forms of mappings, in particular lav and...
Article
Full-text available
Ontology-based data access (OBDA) is a novel paradigm for accessing large data repositories through an ontology, that is a formal description of a domain of interest. Supporting the management of OBDA applications poses new challenges, as it requires to provide effective tools for (i) allowing both expert and non-expert users to analyze the OBDA sp...
Conference Paper
Full-text available
Ontology-based data access (OBDA) is a novel paradigm for ac-cessing large data repositories through an ontology, that is a formal description of a domain of interest. Supporting the management of OBDA applications poses new challenges, as it requires to provide effective tools for (i) allowing both expert and non-expert users to analyze the OBDA s...
Chapter
The work ?Data Integration under Integrity Constraints?, published at the CAiSE 2002 Conference, proposes a rewriting technique for answering queries in data integration systems, when the global schema contains the classical key and foreign key constraints, and the mapping between the data sources and the global schema is of the global-as-view type...
Conference Paper
Full-text available
In ontology-based data access (OBDA), an ontology is connected to autonomous, and generally pre-existing, data repositories through mappings, so as to provide a high-level, conceptual view over such data. User queries are posed over the ontology, and answers are computed by reasoning both on the ontology and the mappings. Query answering in OBDA sy...
Conference Paper
Full-text available
Ontology-based data access (OBDA) is a new paradigm for manag-ing complex information systems through semantic technologies. In this paper we present what we believe is the first industrial experience of a comprehensive OBDA project, developed jointly by Sapienza University of Rome and the De-partment of Treasury of the Italian Ministry of Econonom...
Conference Paper
Full-text available
Artificial Intelligence technologies are growingly used within several software systems ranging from Web services to mobile applications. It is by no doubt true that the more AI algorithms and methods are used the more they tend to depart from a pure "AI" spirit and end to refer to the sphere of standard software. In a sense, AI seems strongly conn...
Article
Several recent techniques and tools for Ontology-based Data Access (OBDA) make use of the so-called extensional constraints (a.k.a. ABox dependencies). So far, extensional constraints have been mainly considered in a setting where data are represented in an ABox, instead of external data sources connected to the ontology through declarative mapping...
Conference Paper
Schema mappings establish a correspondence between data stored in two databases, called source and target respectively. Query processing under schema mappings has been investigated extensively in the two cases where each target atom is mapped to a query over the source (called GAV, global-as-view), and where each source atom is mapped to a query ov...
Conference Paper
Full-text available
In this paper we present the current version of Mastro, a system for ontologybased data access (OBDA) developed at Sapienza Università di Roma. Mastro allows users for accessing external data sources by querying an ontology expressed in a fragment of the W3C Web Ontology Language (OWL). As in data integration [5], mappings are used in OBDA to speci...
Conference Paper
Full-text available
Finding an appropriate semantics for task of updating an inconsistent knowledge base is a challenging problem. In this pa-per, we consider knowledge bases expressed in Description Logics, and focus on ABox inconsistencies, i.e., the case where the TBox is consistent, but the whole knowledge base is not. Our first contribu-tion is the definition of...
Article
View-based query answering is the problem of answering a query based only on the precomputed answers to a set of views. While this problem has been widely investigated in databases, it is largely unexplored in the context of Description Logic ontologies. Differently from traditional databases, Description Logics may express several forms of incompl...
Article
Full-text available
In this paper we present Mastro, a Java tool for ontology-based data access (OBDA) developed at Sapienza Università di Roma. Mastro manages OBDA systems in which the ontology is specified in a logic of the DL-Lite family of Description Logics specifically tailored to ontology-based data access, and is connected to external data management systems t...
Conference Paper
In this paper we introduce the notion of mapping-based knowledge base (MKB) to formalize the situation where both the extensional and the intensional level of the ontology are determined by suitable mappings to a set of (relational) data sources. This allows for making the intensional level of the ontology as dynamic as traditionally the extensiona...
Conference Paper
Full-text available
This paper is motivated by two requirements arising in practical ap-plications of ontology-based data access (OBDA): the need of inconsistency-tolerant semantics, which allow for dealing with classically inconsistent speci-fications; and the need of expressing assertions which go beyond the expressive abilities of traditional Description Logics, na...
Conference Paper
Ontology-based data management aims at accessing and using data by means of an ontology, i.e., a conceptual representation of the domain of interest in the underlying information system. This new paradigm provides several interesting features, many of which have been already proved effective in managing complex information systems. On the other han...
Conference Paper
Full-text available
In this paper we study the problem of obtaining meaningful answers to queries posed over inconsistent DL − Lite ontologies. We consider different variants of inconsistency-tolerant semantics and show that for some of such variants answering unions of conjunctive queries (UCQs) is first-order (FOL) rewritable, i.e., it can be reduced to standard eva...
Article
We investigate an extension of Description Logics (DL) with higher-order capabilities, based on Henkin-style semantics. Our study starts from the observation that the various possibilities of adding higher-order con- structs to a DL form a spectrum of increasing expres- sive power, including domain metamodeling, i.e., using concepts and roles as pr...
Chapter
The article aims at establishing a logical approach to class-based data modeling. After a discussion on class-based formalisms for data modeling, we introduce a family of logics, called Description Logics, which stem from research on Knowledge Representation in Artificial Intelligence. The logics of this family are particularly well suited for spec...
Article
While classic data management focuses on the data itself, research on Business Processes considers also the context in which this data is generated and manipulated, namely the processes, the users, and the goals that this data serves. This allows ...
Conference Paper
Full-text available
Recent papers address the issue of updating the instance level of knowledge bases expressed in Description Logic following a model-based approach. One of the outcomes of these papers is that the result of updating a knowledge base K is generally not expressible in the Descrip-tion Logic used to express K. In this paper we introduce a formula-based...
Conference Paper
Full-text available
A schema mapping is a formal specification of the relationship holding between the databases conforming to two given schemas, called source and target, respectively. While in the general case a schema mapping is specified in terms of assertions relating two queries in some given language, various simplified forms of mappings, in particular LAV and...
Article
Full-text available
The notion of class is ubiquitous in computer science and is central in many formalisms for the representation of structured knowledge used both in knowledge representation and in databases. In this paper we study the basic issues underlying such representation formalisms and single out both their common characteristics and their distinguishing fea...
Article
Full-text available
Recent papers address the issue of updating the instance level of knowledge bases expressed in Description Logic following a model-based approach. One of the outcomes of these papers is that the result of updating a knowledge base K is generally not expressible in the Description Logic used to express K. In this paper we introduce a formula-based a...
Article
Keyword search is a friendly mechanism for users to identify desired information in XML databases, and LCA is a popular concept for locating the meaningful subtrees corresponding to query keywords. Among all the LCA-based approaches, MaxMatch ...
Article
Full-text available
In this paper we present MASTRO, a Java tool for ontology-based data access (OBDA) developed at Sapienza Università di Roma and at the Free University of Bozen-Bolzano. MASTRO manages OBDA systems in which the ontology is specified in DL-Lite A,id, a logic of the DL-Lite family of tractable Description Logics specifically tailored to ontology-based...
Conference Paper
In this paper we introduce the notion of mapping-based knowledge base (MKB), to formalize those ontology-based data access (OBDA) scenarios where both the extensional and the intensional level of the ontology are determined by suitable mapping assertions involving the data sources. We study reasoning over MKBs in the context of Hi(DL-LiteR), a high...
Conference Paper
Full-text available
We investigate an extension of Description Logics (DL) with higher-order capabilities, based on Henkin-style semantics. Our study starts from the observation that the various possibilities of adding higher-order constructs to a DL form a spectrum of increasing expressive power, including domain metamodeling, i.e., using concepts and roles as predic...
Article
We aim at reasoning about actions and about high-level programs over knowledge bases (KBs) expressed in Description Logics (DLs). This is a critical issue that has resisted good, robust solutions for a long time. In particular, while welldeveloped theories of actions and high-level programs exist in AI, e.g., the ones based on the Situation Calculu...
Conference Paper
Full-text available
The study of node-selection query languages for (finite) trees has been a major topic in the recent research on query languages for Web documents. On one hand, there has been an extensive study of XPath and its various extensions. On the other hand, query languages based on classical logics, such as first-order logic (FO) or monadic second-order lo...
Chapter
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One of the outcomes of the research work carried out on data integration in the last years is a clear architecture, comprising a global schema, the source schema and the mapping between the source and the global schema. In this chapter, we study data integration under this framework when the global schema is specified in OWL, the standard language...
Conference Paper
Full-text available
We address the problem of dealing with inconsistencies in Description Logic (DL) knowledge bases. Our general goal is both to study DL semantical frameworks which are inconsistency-tolerant, and to devise techniques for an- swering unions of conjunctive queries posed to DL knowledge bases under such inconsistency-tolerant semantics. Our work is ins...
Article
The study of node-selection query languages for (finite) trees has been a major topic in the recent research on query lan- guages for Web documents. On one hand, there has been an extensive study of XPath and its various extensions. On the other hand, query languages based on classical logics, such as first-order logic (FO) or monadic second-order...
Article
Full-text available
In this paper we consider a powerful mechanism, called Regular XPath, for expressing queries and constraints over XML data, including DTDs and existential path constraints and their negation. Regular XPath extends XPath with binary relations over XML nodes specified by means two-way regular path queries. Our first contribution deals with checking s...
Article
Full-text available
In data management, and in particular in data integration, data exchange, query optimization, and data privacy, the notion of view plays a central role. In several contexts, such as data integration, data mashups, and data warehousing, the need arises of designing views starting from a set of known correspondences between queries over different sch...
Conference Paper
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This paper introduces the general features of Senso Comune, an open knowledge base for the Italian language, focusing on the interplay of lexical and ontological knowledge, and outlining our approach to conceptual knowledge elicitation. Senso Comune consists of a machine-readable lexicon constrained by an ontological infrastructure. The idea at the...
Conference Paper
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We report on an experimentation of Ontology-based Data Access (OBDA) carried out in a joint project with SAPIENZA University of Rome, Free University of Bolzano, and Monte dei Paschi di Siena (MPS), where we used MASTRO for accessing, by means of an ontology, a set of data sources of the actual MPS data repository. By both looking at these sources,...