Filippo Furfaro

• PhD
• Professor (Associate) at University of Calabria

We introduce PERCVER and PERCACC, the problems asking for the percentages of the completions of an incomplete Abstract Argumentation Framework (iAAF) where a set of arguments S is an extension and an argument a is accepted, respectively. These problems give insights into the status of S and a more precise than the “traditional” verification and acc...

We present ACME: A Chatbot for asylum-seeking Migrants in Europe. ACME relies on computational argumentation and aims to help migrants identify the highest level of protection they can apply for. This would contribute to a more sustainable migration by reducing the load on territorial commissions, Courts, and humanitarian organizations supporting a...

We introduce Incomplete Bipolar Argumentation Frameworks (iBAFs), the extension of Dung’s Abstract Argumentation Frameworks (AAFs) allowing the simultaneous presence of supports (borrowed from BAFs – Bipolar AAFs) and of uncertain elements of the argumentation graph (borrowed from iAAFs – incomplete AAFs). We investigate the computational complexit...

In the context of probabilistic AAFs, we intro- duce AAFs with marginal probabilities (mAAFs) requiring only marginal probabilities of argu- ments/attacks to be specified and not relying on the independence assumption. Reasoning over mAAFs requires taking into account multiple probability distributions over the possible worlds, so that the probabil...

Generally, companies and organizations can greatly improve their business processes by suitably monitoring and analyzing the log data that they gather for these processes in the form of traces. We here consider the challenging scenario where there is an abstraction gap between the “low-level” events composing the traces and the “high-level” activit...

The problem of representing and querying sensor network readings issues new research challenges, as traditional techniques and architectures used for managing relational and object oriented databases are not suitable in this context. In this paper, we present a Grid-based framework that supports aggregate query answering on sensor network data, and...

Argumentation Frameworks (att- iAAFs) are a popular extension of AAFs where attacks are marked as uncertain when they are not unanimously per- ceived by different agents reasoning on the same arguments. We here extend att-iAAFs with the possibility of specifying correlations involving the uncertain attacks. This feature sup- ports a unified and mor...

We introduce "argument-incomplete Abstract Argumentation Frameworks with dependencies", that extend the traditional abstract argumentation reasoning to the case where some arguments are uncertain and correlated through logical dependencies (such as mutual exclusion, implication, etc.). We characterize the complexities of the problems DSAT of decidi...

We revisit the notion of i-extension, i.e., the adaption of the fundamental notion of extension to the case of incomplete Abstract Argumentation Frameworks. We show that the definition of i-extension raises some concerns in the "possible" variant, e.g., it allows even conflicting arguments to be collectively considered as members of an (i-)extensio...

We consider the scenario of multiple RFID-tagged objects that simultaneously move across an indoor space where several RFID antennas are placed. We assume that a logical partition of the indoor space into a set of locations is given, along with a set of hard and weak integrity constraints describing both the valid movements of the objects and the c...

Traditionally, Expert Systems have found a natural application in the behavioral analysis of processes. In fact, they have proved effective in the tasks of interpreting the data collected during the process executions and of analyzing these data with the aim of diagnosing/detecting anomalies. In this context, we focus on log data generated by execu...

The complexity of the probabilistic counterparts of the verification and acceptance problems is investigated over probabilistic Abstract Argumentation Frameworks (prAAFs), in a setting more general than the literature, where the complexity has been characterized only under independence between arguments/defeats. The complexity of these problems is...

The complexity of the probabilistic counterparts of the classical verification and acceptance problems is investigated over probabilistic Abstract Argumentation Frameworks (prAAFs), in a setting more general than that considered in the current literature, where the complexity has been characterized only under the assumption of independence between...

Current approaches to the security-oriented classification of process log traces can be split into two categories: (i) example-driven methods, that induce a classifier from annotated example traces; (ii) model-driven methods, based on checking the conformance of each test trace to security-breach models defined by experts. These categories are orth...

Probabilistic Bipolar Abstract Argumentation Frameworks (prBAFs), combining the possibility of specifying supports between arguments with a probabilistic modeling of the uncertainty, are considered, and the complexity of the fundamentalproblem of computing extensions' probabilities is addressed.The most popular semantics of supports and extensions...

There is a growing number of applications where inconsistent information arises. In the last two decades, the emerging approach for dealing with such scenarios is to “tolerate” inconsistency and provide appropriate reasoning mechanisms. In particular, consistent query answering has been widely accepted as a principled approach for query answering....

The problem of classifying business log traces is addressed in the context of security risk analysis. We consider the challenging setting where the actions performed in a process instance are described in the log as executions of low-level operations (such as “Pose a query over a DB”, “Upload a file into an ftp server”), while analysts and business...

Process mining methods have been proven effective in turning historical log data into actionable process knowledge. However, most of them work under the assumption that the events reported in the logs can be easily mapped to well-defined process activities, that are the terms in which analysts are used to reason on the processes’ behaviors. We here...

We discuss an approach for interpreting RFID data in the context of object tracking. It consists in translating the readings generated by RFID-tracked moving objects into semantic locations over a map, by exploiting some integrity constraints. Our approach performs a probabilistic conditioning: it starts from an a-priori probability assigned to the...

Watermarking digital content is a very common approach leveraged by creators of copyrighted digital data to embed fingerprints into their data. The rationale of such operation is to mark each copy of the data in order to uniquely identify it. These watermarks are embedded in a suitable way to prevent their stripping or modification by users for ill...

A probabilistic framework for cleaning the data collected by Radio-Frequency IDentification (RFID) tracking systems is introduced. What has to be cleaned is the set of trajectories that are the possible interpretations of the readings: a trajectory in this set is a sequence whose generic element is a location covered by the reader(s) that made the...

Big data paradigm is currently the leading paradigm for data production and management. As a matter of fact, new information are generated at high rates in specialized fields (e.g., cybersecurity scenario). This may cause that the events to be studied occur at rates that are too fast to be effectively analyzed in real time. For example, in order to...

Log analysis and querying recently received a renewed interest from the research community, as the effective understanding of process behavior is crucial for improving business process management. Indeed, currently available log querying tools are not completely satisfactory, especially from the viewpoint of easiness of use. As a matter of fact, th...

In the context of security risk analysis, we address the problem of classifying log traces describing business process executions. Specifically, on the basis of some (possibly incomplete) knowledge of the process structures and of the patterns representing unsecure behaviors, we classify each trace as instance of some process and/or as potential se...

We consider the scenario where the executions of different business processes are traced into a log, where each trace describes a process instance as a sequence of low-level events (representing basic kinds of operations). In this context, we address a novel problem: given a description of the processes’ behaviors in terms of high-level activities...

The issue of devising efficient and effective solutions for supporting the analysis of process logs has recently received great attention from the research community, as effectively accomplishing any business process management task requires understanding the behavior of the processes. In this paper, we propose a new framework supporting the analys...

The increasing availability of large process log repositories calls for efficient solutions for their analysis. In this regard, a novel specialized compression technique for process logs is proposed, that builds a synopsis supporting a fast estimation of aggregate queries, which are of crucial importance in exploratory and high-level analysis tasks...

An offline cleaning technique is proposed for translating the readings generated by RFID-tracked moving objects into positions over a map. It consists in a grid-based two-way filtering scheme embedding a sampling strategy for addressing missing detections. The readings are first processed in time order: at each time point t, the positions (i.e., ce...

The problem of recovering (count and sum) range queries over multidimensional data only on the basis of aggregate information on such data is addressed. This problem can be formalized as follows. Suppose that a transformation producing a summary from a multidimensional data set is used. Now, given a data set D, a summary S = (D) and a range query r...

RFID-based systems for object tracking and supply chain management have been emerging since the RFID technology proved effective in monitoring movements of objects. The monitoring activity typically results in huge numbers of readings, thus making the problem of efficiently retrieving aggregate information from the collected data a challenging issu...

We address the issue of incorporating a particular yet expressive form of integrity constraints (namely, denial constraints) into probabilistic databases. To this aim, we move away from the common way of giving semantics to probabilistic databases, which relies on considering a unique interpretation of the data, and address two fundamental problems...

We address the issue of incorporating a particular yet expressive form of integrity constraints (namely, denial constraints) into probabilistic databases. To this aim, we move away from the common way of giving semantics to probabilistic databases, which relies on considering a unique interpretation of the data, and address two fundamental problems...

A histogram over a multi-dimensional data set is a synopsis consisting of aggregate data summarizing the values of the points inside non-overlapping ranges of the domain. Owing to their effectiveness in supporting a fast (though approximate) estimation of the answers of aggregate range queries, histograms are widely used in several contexts dealing...

Query relaxation is the process of weakening a query to a more general one, and it is frequently employed to support approximate query answering. In this paper, rewriting systems for a wide fragment of XPath are investigated, which accomplish query relaxation through the application of simple rewriting rules transforming navigational axes and node...

In this chapter, we focus our attention on the evaluation of queries of a form different from that considered in the previous chapters. Specifically, we address the problem of evaluating aggregate queries over data inconsistent w.r.t. aggregate constraints, and introduce a technique for providing range-consistent answers of these queries. The range...

We here discuss limits and possible extensions of the framework presented in the previous chapters for extracting reliable information from numerical data which are inconsistent w.r.t. a given set of aggregate constraints. Specifically, we discuss possible refinements of different aspects, involving the form of constraints, the class of queries, an...

In this chapter, we present a technique for computing card-minimal repairs in the presence of steady aggregate constraints. Thus, differently from the (decision) problems introduced in Chapter 3, we here address a search problem, which is relevant in practice as, in several applications, the availability of a consistent version of the data is manda...

We here introduce the notions which are fundamental for dealing with the problem of extracting reliable information from (inconsistent) data in the presence of aggregate constraints. Specifically, we formalize the basic concepts of aggregate constraint, repair, repair minimality, and consistent answer, which will be exploited in the following chapt...

In this chapter, we introduce some fundamental decision problems related to repairing and querying inconsistent data. Specifically, we formalize the repair existence problem, the minimal repair checking problem, and the consistent query answer problem, and analyze their computational complexity in the presence of databases inconsistent w.r.t. a giv...

Evaluating aggregate range queries by accessing a compressed representation of the data is a widely adopted solution to the problem of efficiently retrieving aggregate information from large amounts of data. Although several summarization techniques have been proposed which are effective in reducing the amount of time needed for computing aggregate...

A P2P-based framework supporting the extraction of aggregates from historical multidimensional data is proposed, which provides efficient and robust query evaluation. When a data population is published, data are summarized in a synopsis, consisting of an index built on top of a set of subsynopses (storing compressed representations of distinct dat...

A framework for computing range-consistent answers of aggregate queries in the presence of aggregate constraints is introduced. The range-consistent answer of an aggregate query is the narrowest interval containing all the answers of the query evaluated on every possible repaired database. A wide form of aggregate constraints is considered, consist...

A framework for computing consistent answers to boolean aggregate queries in numerical databases violating a given set of aggregate constraints is introduced. Both aggregate constraints and queries are aggregation expressions consisting of linear inequalities on aggregate-sum functions. In particular, our approach works for a specific but expressiv...

The problem of extracting consistent information from relational databases violating integrity constraints on numerical data is addressed. In particular, aggregate constraints defined as linear inequalities on aggregate-sum queries on input data are considered. The notion of repair as consistent set of updates at attribute-value level is exploited,...

The problem of defining suitable rewriting mechanisms for XML query languages to support approximate query answering has received a great deal of attention in the last few years, owing to its practical impact in several scenarios. For instance, in the typical scenario of distributed XML data without a shared data scheme, accomplishing the extractio...

The main drawbacks of handheld devices (small storage space, small size of the display screen, discontinuance of the connection to the WLAN etc) are often incompatible with the need of querying and browsing information extracted from enormous amounts of data which are accessible through the network. In this application scenario, data compression an...

Radio Frequency Identification (RFID) applications are emerging as key components in object tracking and supply chain management systems since in the next future almost every major retailer will use RFID systems to track the shipment of products from suppliers to warehouses. Due to the streaming nature of RFID readings, large amounts of data are ge...

Sensor networks represent a leading case of data stream sources coming from real-life application scenarios. Sensors are non-reactive elements which are used to monitor real-life phenomena, such as live weather conditions, network traffic etc. They are usually organized into networks where their readings are transmitted using low level protocols. A...

A framework for the partial evaluation of SPARQL queries on multiple RDF data sources, both at a local and global level, is proposed. According to the proposed approach, global evaluation of queries is accomplished by first performing local evaluation on each data source, then merging the obtained results. When merging the results, term equivalence...

An iceberg cube is a refinement of a data cube containing the subset of cells whose measure is larger than a given threshold (iceberg condition). Iceberg cubes are well-established tools supporting fast data analysis, as they filter the information contained in classical data cubes to provide the most relevant pieces of information. Although the pr...

The problem of summarizing multi-dimensional data into lossy synopses supporting the estimation of aggregate range queries has been deeply investigated in the last three decades. Several summarization techniques have been proposed, based on different approaches, such as histograms, wavelets and sampling. The aim of most of the works in this area wa...

Hierarchical binary partitions of multi-dimensional data are investigated as a basis for the construction of effective histograms. Specifically, the impact of adopting lossless compression techniques for representing the histogram on both the accuracy and the efficiency of query answering is investigated. Compression is obtained by exploiting the h...

XML queries are usually expressed by means of XPath expressions identifying portions of the selected documents. An XPath expression defines a way of navigating an XML tree and returns the set of nodes which are reachable from one or more starting nodes through the paths specified by the expression. The problem of efficiently answering XPath queries...

The problem of managing and querying inconsistent databases has been deeply investigated in the last few years. As the problem of consistent query answering is hard in the general case, most of the techniques proposed so far have an exponential complexity. Polynomial techniques have been proposed only for restricted forms of constraints (such as fu...

The widespread use of graph-based models for representing data collections (e.g. object-oriented data, XML data, etc.) has stimulated the database research community to investigate the problem of defining declarative languages for querying graph-like databases. In this paper, a new framework for querying graph-like data based on graph grammars is p...

Path queries have been extensively used to query semistructured data, such as the Web and XML documents. In this paper we introduce weighted path queries, an extension of path queries enabling several classes of optimization problems (such as the computation of shortest paths) to be easily expressed. Weighted path queries are based on the notion of...

An architecture is proposed providing robust data acquisition facilities from input documents containing tabular data. This architecture is based on a data-repairing framework exploiting integrity constraints defined on the input data to support the detection and the repair of inconsistencies in the data arising from errors occurring in the acquisi...

Density-based clusterization techniques are investigated as a basis for constructing histograms in multi-dimensional scenarios, where traditional tech- niques fail in providing effective data synopses. The main idea is that locating dense and sparse regions can be exploited to partition the data into homogeneous buckets, preventing dense and sparse...

The problem of representing and querying sensor network readings issues new research challenges, as traditional techniques and architectures used for managing relational and object oriented databases are not suitable in this context. In this paper, we present a Grid-based framework that supports aggregate query answering on sensor network data, and...

The problem of repairing XML data which are inconsistent and incomplete with respect to a set of integrity constraints and a DTD is addressed. The existence of repairs (i.e. minimal sets of update operations making data consistent) is investigated and shown to be undecidable in the general case. This pro-blem is shown to be still undecidable when d...

A new technique for constructing multi-dimensional histograms is proposed. This technique first invokes a density-based clustering algorithm to locate dense and sparse regions of the input data. Then the data distribution inside each of these regions is summarized by partitioning it into non-overlapping blocks laid onto a grid. The granularity of t...

The problem of extracting consistent information from relational databases violating integrity constraints on numerical data is addressed. In particular, aggregate constraints defined as linear inequalities on aggregate-sum queries on input data are considered. The notion of repair as consistent set of updates at attribute-value level is exploited,...

A distributed system for approximate query answering on sensor network data is proposed, where a suitable compression technique is exploited to represent data and support query answering. Each node of the system stores either detailed or summarized sensor readings. Query answers are computed by identifying the set of nodes that contain (either comp...

A distributed system for approximate query answering on sensor network data is proposed, where a suitable compression technique is exploited to represent data and support query answering. Each node of the system stores either detailed or summarized sensor readings. Query answers are computed by identifying the set of nodes that contain (either comp...

The need to compress data into synopses of summarized information often arises in many application scenarios, where the aim is to retrieve aggregate data efficiently, possibly trading off the computational efficiency with the accuracy of the estimation. A widely used approach for summarizing multi-dimensional data is the histogram-based representat...

The problem of recovering (count and sum) range queries over multidimensional data only on the basis of aggregate information on such data is addressed. This problem can be formalized as follows. Suppose that a transformation T producing a summary from a multidimensional data set is used. Now, given a data set D, a summary S=T(D) and a range query...

The problem of recovering (count and sum) range queries over multidimensional data only on the basis of aggregate information on such data is addressed. This problem can be formalized as follows. Suppose that a transformation T producing a summary from a multidimensional data set is used. Now, given a data set D, a summary S=T(D) and a range query...

The World Wide Web is of strategic importance as a global repository for information and a means of communicating and sharing knowledge. Its explosive growth has caused deep changes in all the aspects of human life, has been a driving force for the development of modern applications (e.g., Web portals, digital libraries, wrapper generators, etc.),...

The problem of representing and querying sensor-network data issues new research challenges, as traditional techniques and architectures used for managing relational and object oriented data- bases are not suitable in this context. In this paper we present a Grid-based architecture that supports aggregate query answering on sensor network data, and...

In this paper, we propose a variant of stable model semantics for disjunctive logic programming and deductive databases. The semantics, called minimal founded, generalizes stable model semantics for normal (i.e. non disjunctive) programs but differs from disjunctive stable model semantics (the extension of stable model semantics for disjunctive pro...

The need to compress,data into synopses,of summarized,informa- tion often arises in many application scenarios, where the aim is to retrieve ag- gregate data efficiently, possibly trading off the computational efficiency with the accuracy of the estimation. A widely used approach,for summarizing,multi- dimensional data is the histogram-based repres...

In this paper we consider the problem of XML data which may be inconsistent with respect to a set of functional dependencies. We propose a technique for computing repairs (minimal sets of update operations making data consistent) and consistent answers. More specifically, our repairs are based on i) the replacing of values associated with attribute...

In many application contexts, like statistical databases, scientific databases, query optimizers, OLAP, and so on, data are often summarized into synopses of aggregate values. Summarization has the great advantage of saving space, but querying aggregate data rather than the original ones introduces estimation errors which cannot be in general avoid...

XML queries are usually expressed by means of XPath expressions identifying portions of the selected documents. An XPath expression defines a way of navigating an XML tree and returns the set of nodes which are reachable from one or more starting nodes through the paths specied by the expression. The prob- lem of efficiently answering XPath queries...

Sensor networks represent a non traditional source of information, as readings generated by sensors o w continuously, leading to an innite stream of data. Traditional DBMSs, which are based on an exact and detailed representation of information, are not suitable in this context, as all the information carried by a data stream cannot be stored withi...

The main drawbacks of handheld devices (small storage space, small size of the display screen, discontinuance of the connection to the WLAN, etc.) are often incompatible with the need of querying and browsing information extracted from the enormous amount of data which are accessible through the network. In this application scenario, the issues of...

In many application contexts, like statistical databases, transaction recording systems, scientific databases, query optimizers, OLAP, and so on, data are summarized as histograms of aggregate values. When the task of reconstructing range queries on original data from aggregate data is performed, a certain estimation error cannot be avoided, due to...

In this paper, we explore the possibility of transforming queries with minimum and maximum predicates into equivalent queries that can be computed more efficiently. The main contribution of the paper is an algorithm for propagating min and max predicates while preserving query equivalence under certain monotonicity constraints. We show that the alg...

In this paper we present a graphical query language for XML. The language, based on a simple form of graph grammars, permits us to extract data and reorganize information in a new structure. As with most of the current query languages for XML, queries consist of two parts: one extracting a subgraph and one constructing the output graph. The semanti...

Recent research has investigated the problem of querying semi-structured data and data which can be represented by means of graphs (e.g. object-oriented data, XML data, etc.). Typically queries on graph-like data, called path queries, are expressed by means of regular expressions denoting paths in the graph. The result of a path query is the set of...

Informally presents the query language 𝒳𝒢L (eXtensible Graphical Language). The main features of the language are described by means of two queries on a document named "bib.xml" (a document describing the bibliographic details of a book)

In this paper we present a graphical query language for XML. The language, based on a simple form of graph grammars, permits us to extract data and reorganize information in a new structure. As with most of the current query languages for XML, queries consist of two parts: one extracting a sub-graph and one constructing the output graph. The semant...

In this paper we present a new technique for detecting changes on the Web. We propose a new method to measure the similarity of two documents, that can be efficiently used to discover changes in selected portions of the original document. The proposed technique has been implemented in the CDWeb system providing a change monitoring service on theWeb...

Recently research has deeply investigated the problem of querying semi-structured data and data which can be represented by means of graphs (e.g. object-oriented data, XML data, etc.). Typically queries on graph-like data, called path queries, are expressed by means of regular expressions denoting paths in the graph. The result of a path query is t...

Often Web users want to be notified when specific information contained in a Web page has been modified. The problem of detecting Web document changes has been deeply investigated and several systems providing notification of Web page changes are available. These systems do not provide notification of changes on specific information contained in a...