In the last decade, Social Networks (SNs) have deeply changed many aspects of society, and one of the most widespread behaviours is the sharing of pictures. However, malicious users often exploit shared pictures to create fake profiles,... more
In the last decade, Social Networks (SNs) have deeply changed many aspects of society, and one of the most widespread behaviours is the sharing of pictures. However, malicious users often exploit shared pictures to create fake profiles, leading to the growth of cybercrime. Thus, keeping in mind this scenario, authorship attribution and verification through image watermarking techniques are becoming more and more important. In this paper, we firstly investigate how thirteen of the most popular SNs treat uploaded pictures in order to identify a possible implementation of image watermarking techniques by respective SNs. Second, we test the robustness of several image watermarking algorithms on these thirteen SNs. Finally, we verify whether a method based on the Photo-Response Non-Uniformity (PRNU) technique, which is usually used in digital forensic or image forgery detection activities, can be successfully used as a watermarking approach for authorship attribution and verification of ...
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One of the important problems in the domain of network science is the community detection. In the past, various topological based community detection algorithms have been proposed. Recently, researchers have taken into account at-... more
One of the important problems in the domain of network science is the community detection. In the past, various topological based community detection algorithms have been proposed. Recently, researchers have taken into account at- tributes of the nodes while proposing community detection algorithms. In this work, we investigate if the nodes in a community, identified through topology based algorithms al- so exhibit attribute similarity. Using four different kinds of similarity metrics, we analyse the attribute similarity of the nodes within the communities derived using five different types of topological based community detection algorithms. Based on our analysis of three real social network datasets, we found on an average of 50% attribute similarity among the nodes in the communities.
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Current hierarchical embeddings are inaccurate in both reconstructing the original taxonomy and answering reachability queries over Direct Acyclic Graph. In this paper, we propose a new hierarchical embedding, the Euclidean Embedding... more
Current hierarchical embeddings are inaccurate in both reconstructing the original taxonomy and answering reachability queries over Direct Acyclic Graph. In this paper, we propose a new hierarchical embedding, the Euclidean Embedding (EE), that is correct by design due to its mathematical formulation and associated lemmas. Such embedding can be constructed during the visit of a taxonomy, thus making it faster to generate if compared to other learning-based embeddings. After proposing a novel set of metrics for determining the embedding accuracy with respect to the reachability queries, we compare our proposed embedding with state-of-the-art approaches using full trees from 3 to 1555 nodes and over a real-world Direct Acyclic Graph of 1170 nodes. The benchmark shows that EE outperforms our competitors in both accuracy and efficiency.
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In the graph database literature the term "join" does not refer to an operator used to merge two graphs. In particular, a counterpart of the relational join is not present in existing graph query languages, and consequently no... more
In the graph database literature the term "join" does not refer to an operator used to merge two graphs. In particular, a counterpart of the relational join is not present in existing graph query languages, and consequently no efficient algorithms have been developed for this operator. This paper provides two main contributions. First, we define a binary graph join operator that acts on the vertices as a standard relational join and combines the edges according to a user-defined semantics. Then we propose the "CoGrouped Graph Conjunctive $\theta$-Join" algorithm running over data indexed in secondary memory. Our implementation outperforms the execution of the same operation in Cypher and SPARQL on major existing graph database management systems by at least one order of magnitude, also including indexing and loading time.
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In the graph database literature the term “join” does not refer to an operator combining two graphs, but involves path traversal queries over a single graph. Current languages express binary joins ...
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In recent years, social networks (SNs) have revolutionized many aspects of society. The wide variety of available platforms meets almost every kind of users’ needs: socialization, professional connections and image sharing, to name a few.... more
In recent years, social networks (SNs) have revolutionized many aspects of society. The wide variety of available platforms meets almost every kind of users’ needs: socialization, professional connections and image sharing, to name a few. Smartphones have brought vital change in user’s behaviour towards sharing of multimedia content on online SNs. One of the noticeable behaviour is taking pictures using smartphone’s camera and sharing them with contacts through online social platforms. On the flip side, SNs have contributed to the growth of the cyber crime and one of the main aspect of social networks security is to identify fake profiles. In this paper, we present a method to verify and resolve user profiles in SNs using the images posted on them, assuming taken through user’s smartphone. Creating a sort of fingerprint of the user profile, the method is capable enough to resolve profiles in spite of the fact that the images get downgraded during the uploading/downloading process. A...
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The popularity of social networks (SNs), amplified by the ever-increasing use of smartphones, has intensified online cybercrimes. This trend has accelerated digital forensics through SNs. One of the areas that has received lots of... more
The popularity of social networks (SNs), amplified by the ever-increasing use of smartphones, has intensified online cybercrimes. This trend has accelerated digital forensics through SNs. One of the areas that has received lots of attention is camera fingerprinting, through which each smartphone is uniquely characterized. Hence, in this paper, we compare classification-based methods to achieve smartphone identification (SI) and user profile linking (UPL) within the same or across different SNs, which can provide investigators with significant clues. We validate the proposed methods by two datasets, our dataset and the VISION dataset, both including original and shared images on the SN platforms such as Google Currents, Facebook, WhatsApp, and Telegram. The obtained results show that k-medoids achieves the best results compared with k-means, hierarchical approaches, and different models of convolutional neural network (CNN) in the classification of the images. The results show that k...
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In the last decade, various social platforms have been introduced on the web. Due to their specific orientation (friendship, professional connections, image sharing, etc.) users often join multiple networks. An important problem across... more
In the last decade, various social platforms have been introduced on the web. Due to their specific orientation (friendship, professional connections, image sharing, etc.) users often join multiple networks. An important problem across these networks is the resolution of users profiles. That is, to identify if set of user profiles from different networks with different user ids or nicknames belong to the same user. The problem is more meaningful for resolving different profiles in digital forensic and criminal investigations. In this paper, we propose a method for profile resolution with the help of pictures being posted on different social platforms. We use the smartphone cameras which have become the source of instant image capturing and uploading process. In particular, we exploit the characteristic noise present in the images due to the manufacturing defects, to match user profiles across social platforms. To test our approach we select five different smartphones with two pairs of identical models, and three social platforms, namely Facebook, Google+ and WhatsApp. We evaluate our approach using real dataset of 1000 high-resolution pictures. The results indicate that even in the worst case our approach can provide profile matching upto 89.83%.
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In this paper we propose a logic-based language, CLP\\((\\mathcal{A}\\mathcal{D})\\) which is an instance of the Constraint Logic Programming schema and is a convenient semantic framework to be used for deductive database language with... more
In this paper we propose a logic-based language, CLP\\((\\mathcal{A}\\mathcal{D})\\) which is an instance of the Constraint Logic Programming schema and is a convenient semantic framework to be used for deductive database language with updates. CLP\\((\\mathcal{A}\\mathcal{D})\\) can be seen as an extension of Datalog with base relations updates and the notion of transaction. The semantics of this language is given in two steps and is based on a notion of observable corresponding to the computed answer constraint. Moreover, some useful notions of equivalence between databases with respect to a transaction and between transactions with respect to a database are given.
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This chapter presents a fuzzy-based algebra, called SAMEW, to query multimedia objects. SAMEW allows for dealing within a common framework with several aspects relevant to similarity query processing as well as with the inherent... more
This chapter presents a fuzzy-based algebra, called SAMEW, to query multimedia objects. SAMEW allows for dealing within a common framework with several aspects relevant to similarity query processing as well as with the inherent imprecision that characterizes data, user requests and query results. Non-Boolean, namely fuzzy and similarity, predicates are used to rank tuples according to specific criteria. Complex multi-predicate queries can be formed by means of logical connectives, whose semantics is parameterized in order to adapt to specific scenarios. The same holds for the semantics of algebraic operators. These include properly extended traditional relational operators and new operators which allow threshold and best-matches queries to be easily expressed. A further important feature of SAMEW is the possibility of weighting both predicates and operands of algebraic operators so as to better fit user preferences/requirements. A working example dealing with Web data is used throu...
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. Integrity constraints are usually assumed to be permanentproperties that must be satisfied by any database state. However, thereare many situations requiring also temporary constraints, that is, constraintsthat must hold only for a... more
. Integrity constraints are usually assumed to be permanentproperties that must be satisfied by any database state. However, thereare many situations requiring also temporary constraints, that is, constraintsthat must hold only for a single database state. In this paper wepropose a schema to define both permanent and temporary constraints,that supports efficient constraint checking and semantic query optimization.The proposed schema associates integrity constraints to rules andqueries,...
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ABSTRACT
Page 1. Rules Termination Analysis Investigating the Interaction between Transactions and Triggers Danilo Montesi £ Dip. Scienze Informazione Universitèa di Bologna Mura Anteo Zamboni, 7 40127 Bologna, Italy Elisa Bertino Ý , Maria... more
Page 1. Rules Termination Analysis Investigating the Interaction between Transactions and Triggers Danilo Montesi £ Dip. Scienze Informazione Universitèa di Bologna Mura Anteo Zamboni, 7 40127 Bologna, Italy Elisa Bertino Ý , Maria Bagnato Þ Dip. ...
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Deductive databases with updates in rule bodies do not allow bottom-up execution model. This is due to the introduction of control in rule bodies. However, bottom-up execution models are very important due to the set oriented... more
Deductive databases with updates in rule bodies do not allow bottom-up execution model. This is due to the introduction of control in rule bodies. However, bottom-up execution models are very important due to the set oriented queryanswering process of database systems. In [4] we have proposed a rule language to avoid the above drawback and to provide transaction optimization through transaction transformation. In this paper we describe a prototype that provide a bottom-up meta interpreter for the database rule language and will allow to check the validity of future extensions theoretical conjecture about transaction optimization and integrity constraints. The experience in the use of KBMS1 as a tool to develop a run time support for the rule language is reported together with an overview of the system architecture. This work has been supported by a grant from the Italian National Research Council. y The work of D. Montesi has been partly supported by the ERCIM fellowship Informatio...
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Towards a unified model for heterogeneous data – p. 1
PDF and gzipped PostScript formats via anonymous FTP from the areaftp.cs.unibo.it:/pub/TR/UBLCS or via WWW at
or via WWW,at URLhttp://www.cs.unibo.it/. Plain-text abstracts organized,by year are available in the directoryABSTRACTS. Recent Titles from the UBLCS Technical Report Series 2006-23 Emergent Social Rationality in a Peer-to-Peer System,... more
or via WWW,at URLhttp://www.cs.unibo.it/. Plain-text abstracts organized,by year are available in the directoryABSTRACTS. Recent Titles from the UBLCS Technical Report Series 2006-23 Emergent Social Rationality in a Peer-to-Peer System, Marcozzi, A., Hales, D., October 2006.
or via WWW at URL http://www.cs.unibo.it/. Plain-text abstracts organized by year are available in the directory ABSTRACTS. All local authors can be reached via e-mail at the address last-name[at]cs.unibo.it. Recent Titles from the UBLCS... more
or via WWW at URL http://www.cs.unibo.it/. Plain-text abstracts organized by year are available in the directory ABSTRACTS. All local authors can be reached via e-mail at the address last-name[at]cs.unibo.it. Recent Titles from the UBLCS Technical Report Series 2003-5 Synchronized Hypermedia Documents: a Model and its Applications (Ph.D. Thesis), Gaggi, O., March 2003.
Uncertainty is an intrinsic feature of automatic and semi- automatic data integration processes. Although many solutions have been proposed to reduce uncertainty, if we do not explicitly represent and keep it up to the end of the... more
Uncertainty is an intrinsic feature of automatic and semi- automatic data integration processes. Although many solutions have been proposed to reduce uncertainty, if we do not explicitly represent and keep it up to the end of the integration process we risk to lose rel- evant information, and to produce misleading results. Models for uncer- tain data can then be used to represent integrated data sources resulting from uncertain data integration processes. In this paper we present a survey of existing approaches directly dealing with uncertainty in data integration, dene a generic data integration process that explicitly rep- resents uncertainty during all its steps, and present some preliminary results and open issues in the eld.
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The Global-As-View approach in data integration system has focused on the (semi-) automatic de nition of a global schema starting from a given set of known information sources. In this paper, we investigate how to employ concepts and... more
The Global-As-View approach in data integration system has focused on the (semi-) automatic de nition of a global schema starting from a given set of known information sources. In this paper, we investigate how to employ concepts and techniques to model imprecision in generating the global schema and in specifying the mappings. We propose a language for de ning fuzzy-based mappings between source and global schemas. Such mappings explicitly take into account the similarities occurring between global and source schemas, thus allowing to discard the items with low similarity and to express the relevances that dierent sources may have in populating the global schema. The proposed language is applied in the framework of the ARTEMIS/MOMIS integration system.
In this paper, we develop a new approach that provides a smooth integration of extensional updates and declarative query languages for deductive databases. The approach is based on a declarative specification of updates in rule bodies.... more
In this paper, we develop a new approach that provides a smooth integration of extensional updates and declarative query languages for deductive databases. The approach is based on a declarative specification of updates in rule bodies. Updates are not executed as soon as evaluated. Instead, they are collected and then applied to the database when the query evaluation is completed.
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ABSTRACT A basic problem in the analysis of social networks is missing data. When a network model does not accurately capture all the actors or relationships in the social system under study, measures computed on the network and... more
ABSTRACT A basic problem in the analysis of social networks is missing data. When a network model does not accurately capture all the actors or relationships in the social system under study, measures computed on the network and ultimately the final outcomes of the analysis can be severely distorted. For this reason, researchers in social network analysis have characterised the impact of different types of missing data on existing network measures. Recently a lot of attention has been devoted to the study of multiple-network systems, e.g., multiplex networks. In these systems missing data has an even more significant impact on the outcomes of the analyses. However, to the best of our knowledge, no study has focused on this problem yet. This work is a first step in the direction of understanding the impact of missing data in multiple networks. We first discuss the main reasons for missingness in these systems, then we explore the relation between various types of missing information and their effect on network properties. We provide initial experimental evidence based on both real and synthetic data.
In this paper we present a model for the management of relational, XML, and mixed data. The main high-level ap-proaches to manipulate XML, ie, SQL/XML, XQuery, and Object/Relational XML columns, can all be based on our common model and... more
In this paper we present a model for the management of relational, XML, and mixed data. The main high-level ap-proaches to manipulate XML, ie, SQL/XML, XQuery, and Object/Relational XML columns, can all be based on our common model and algebra. Our query algebra, ...