Umberto Nanni

The visualization of large graphs in interactive applications, specifically on small devices, can make harder to understand and analyze the displayed information. We show as simple topological properties of the graph can provide an efficient automatic computation of features which improves the "readibility" of a large graph by a proper selection of the displayed information. The connectivity (existence of a path) is a very intuitive structural property of a network; in this paper we propose an approach to the visualization of a network based on connectivity and related concepts as effective tools for visual analysis. In particular, given a root vertex r and a target vertex t, it is possible to check at a glance if there are some dominators, i.e., mandatory vertices that are on every path from r to t. Furthermore, using a recent graph algorithm from Georgiadis and Tarjan [19], [20], by selecting a target vertex it is possible to see two distinct paths from r to t: the paths...

The problem of Entity relation discovery in structured<br> data, a well covered topic in literature, consists in searching within<br> unstructured sources (typically, text) in order to find connections<br> among entities. These can be a whole dictionary, or a specific<br> collection of named items. In many cases machine learning and/or<br> text mining techniques are used for this goal. These approaches<br> might be unfeasible in computationally challenging problems, such<br> as processing massive data streams. A faster approach consists in collecting the cooccurrences of any<br> two words (entities) in order to create a graph of relations - a<br> cooccurrence graph. Indeed each cooccurrence highlights some grade<br> of semantic correlation between the words because it is more common<br> to have related words close each other than having them in the<br> opposite sides of the text. Some authors have used sliding w...

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Abstract. It is widely known that spectral techniques are very effective for document retrieval. Recently, a lot of effort has been spent by researchers to provide a formal mathematical explanation for this effectiveness [3]. Latent Semantic Indexing, in particular, is a text retrieval algorithm based on the spectral analysis of the occurrences of terms in text documents. Despite of its value in improving the quality of a text search, LSI has the drawback of an elevate response time, which makes it unsuitable for on-line search in large collections of documents (e.g., web search engines). In this paper we present two approaches aimed to combine the effectiveness of latent semantic analysis with the efficiency of text matching retrieval, through the technique of query expansion. We show that both approaches have relatively small computational cost and we provide experimental evidence of their ability to improve document retrieval. 1

The growing demand of personalized medicine marked the transition from an empirical medicine to a molecular one, aimed at predicting safer and more effective medical treatment for every patient, while minimizing adverse effects. This passage has emphasized the importance of biomarker discovery studies, and has led sample availability to assume a crucial role in biomedical research. Accordingly, a great interest in Biological Bank science has grown concomitantly. In biobanks, biological material and its accompanying data are collected, handled and stored in accordance with standard operating procedures (SOPs) and existing legislation. Sample quality is ensured by adherence to SOPs and sample whole life-cycle can be recorded by innovative tracking systems employing information technology (IT) tools for monitoring storage conditions and characterization of vast amount of data. All the above will ensure proper sample exchangeability among research facilities and will represent the start...

(Extended We consider the problem of maintaining the distances and the shortest paths from a single source in either a directed or an undirected graph with positive real edge weights, handling insertions, deletions and cost updates of edges. We propose fully dynamic algorithms with optimal space requirements and query time. The cost of update operations depends on the class of

The growing demand of personalized medicine marked the transition from an empirical medicine to a molecular one, aimed at predicting safer and more effective medical treatment for every patient, while minimizing adverse effects. This passage has emphasized the importance of biomarker discovery studies, and has led sample availability to assume a crucial role in biomedical research. Accordingly, a great interest in Biological Bank science has grown concomitantly. In biobanks, biological material and its accompanying data are collected, handled and stored in accordance with standard operating procedures (SOPs) and existing legislation. Sample quality is ensured by adherence to SOPs and sample whole life-cycle can be recorded by innovative tracking systems employing information technology (IT) tools for monitoring storage conditions and characterization of vast amount of data. All the above will ensure proper sample exchangeability among research facilities and will represent the start...

We report on experience related to the online training for the Italian and International Olympiads in Informatics (IOI). We developed an interactive online system, integrating the programming problems and the grading system used in several major programming contests, including the IOI. The system has been used in three distinct contexts: training students for the Italian Olympiads in Informatics (OII), training teachers in order to be able to assist students for the OII, and training the Italian team for the IOI. We also present the initial design of an extension deemed to provide trainees with a personalized support to skills’ enhancement on contest problems.

We consider the problem of maintaining minimum length paths in a directed graph G=(V,E) with n nodes while inserting new arcs. A data structure which supports the following operations is presented: an add operation, which inserts an arc in the digraph, and a minpath operation, which returns a minimal length path between a pair of nodes. The data structure supports each minpath operation in O(k) worst case time, where k<n is the length of the returned path; moreover, if we assume that the weights of the arcs are integer numbers in the range [1…W], then the expected cost of any sequence of add operations is O(min(n4, n3max(W, logn))) time. The space complexity is O(n2). The same algorithm can be used for solving the problem of maintaining maximum length paths when the digraph is acyclic and add operations preserve acyclicity.

ABSTRACT In this paper we focus on the problem of finding personalized learning paths in presence of a large number of available learning components. In particular, we model the relationships holding between learning activities and the related (needed/achieved) competence, by adopting directed hypergraph. We show as the complexity of optimizing learning paths depends dramatically on the adopted metrics; in particular, we prove that finding a learning path with minimum timespan can be done in quasi-linear time, whilst finding one with minimum total effort (apparently, a very similar problem) is NP-hard. Therefore in some cases, it is possible to use simple and fast algorithms for computing personalized e-learning paths, while in other cases the developers must rely on approximated heuristics, or adequate computational resources. We are implementing this modeling and the related algorithms in the framework provided by the LECOMPS system for personalized e-learning. The final aim is to apply the modeling in large repositories, or in wider web-based e-learning environments.

ABSTRACT The visualization of large graphs in interactive applications, specifically on small devices, can make harder to understand and analyze the displayed information. We show as simple topological properties of the graph can provide an efficient automatic computation of properties which improves the “readability” of a large graph by a proper selection of the displayed information. We show an approach to the visualization of a learning activity based on connectivity and related concepts as effective tools for visual analysis by learners, and by administrator of a repository.

Biobanks provide stored material to basic, translational, and epidemiological research and this material should be transferred without institute-dependent intrinsic bias. The ISBER Biospecimen Science Working Group has released a &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Standard PREanalytical Code&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; (SPREC), which is a proposal for a standard coding of the preanalytical options that have been adopted in order to track and make explicit the preanalytical variations in the collection, preparation, and storage of specimens. In this paper we address 2 issues arising in any biobank or biolaboratory aiming at adopting SPREC: (i) reducing the burden required to adopt this standard coding, and (ii) maximize the immediate benefits of this adoption by providing a free, dedicated software tool. We propose SPRECware, a vision encompassing tools and solutions for the best exploitation of SPREC based on information technology (www.sprecware.org). As a first step, we make available SPRECbase, a software tool useful for generating, storing, managing, and exchanging SPREC-related information associated to specimens. Adopting SPREC is useful both for internal purposes (such as finding the samples having some given preanalytical features), and for exchanging the preanalytical information associated to biological samples between Laboratory Information Systems. In case of a common adoption of this coding, it would be easy to find out whether and where, among the participating Biological Resource Centers, the specimens for a given study are available in order to carry out a planned experiment.