Luigi Laura

Università degli Studi "La Sapienza" di Roma, Computer and Systems Science, Post-Doc

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B. Harun Küçük

University of Pennsylvania

Naim Kapucu

University of Central Florida

Maurizio Forte

Duke University

David Seamon

Kansas State University

Christopher Witmore

Texas Tech University

Armando Marques-Guedes

UNL - New University of Lisbon

Noe Cornago

University of the Basque Country, Euskal Herriko Unibertsitatea

Jonathan Jarrett

University of Leeds

Kati (Katalin) Prajda

University of Vienna

Hadi Winarto

RMIT International University Vietnam

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Papers by Luigi Laura

eGovernment Interventions: The Multiple Projects Evaluation Problem

Communications in Computer and Information Science, 2014

Large-Scale Graph Biconnectivity in MapReduce

Department of Computer and System Sciences Antonio Ruberti Technical Reports, 2012

The MapReduce framework, originally proposed by Google [8], and its open source implementation, H... more The MapReduce framework, originally proposed by Google [8], and its open source implementation, Hadoop [27], are nowadays considered the standard frameworks, both in industry and academia, to deal with petabyte scale datasets. In this paper we describe a two-rounds MapReduce approach to biconnectivity in undirected graphs, that is the computation of the set of articulation points, the set of bridges and the set of biconnected components of a graph G. We recall that an articulation point (resp. a bridge) is a vertex (resp. an edge) whose removal increases the number of connected components. A biconnected component is a maximal biconnected subgraph, i.e., it does not include neither articulation points nor bridges.

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The Organization of Large-Scale Repositories of Learning Objects with Directed Hypergraphs

Lecture Notes in Computer Science, 2014

ABSTRACT In this paper we focus on the problem of finding personalized learning paths in presence... more 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.

Visual Analysis Based on Dominator Trees with Application to Personalized eLearning

Lecture Notes in Computer Science, 2014

ABSTRACT The visualization of large graphs in interactive applications, specifically on small dev... more 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.

The Interface of VISTO, a New Vector Image Search Tool

Lecture Notes in Computer Science, 2007

MJ Smith, G. Salvendy (Eds.): Human Interface, Part I, HCII 2007, LNCS 4557, pp. 417426, 2007. ©... more

Vertical Semantic Discovery: The SICH Approach on NPS

2014 International Conference on Intelligent Networking and Collaborative Systems, 2014

Dynamic subtrees queries revised: the Depth First Tour Tree

Finding Strong Articulation Points And Strong Bridges in Linear Time

Experimental Evaluation of Algorithms for the Food-Selection Problem

In this paper, we describe the result of our experiments on Algorithms for the Food-Selection Pro... more In this paper, we describe the result of our experiments on Algorithms for the Food-Selection Problem, which is the fundamental problem first stated and addressed in the seminal paper . Because the key aspect of any experimental evaluation is the reproducibility, we detail deeply the setup of all our experiments, thus leaving to the interested eater the opportunity to reproduce all the results described in this paper. More specifically, we describe all the answers we provided to the questions proposed in [1]:

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2-Vertex Connectivity in Directed Graphs

Is Timetabling Routing Always Reliable for Public Transportl

2-Edge Connectivity in Directed Graphs

Proceedings of the Twenty-Sixth Annual ACM-SIAM Symposium on Discrete Algorithms, 2014

Edge and vertex connectivity are fundamental concepts in graph theory. While they have been thoro... more Edge and vertex connectivity are fundamental concepts in graph theory. While they have been thoroughly studied in the case of undirected graphs, surprisingly not much has been investigated for directed graphs. In this paper we study 2-edge connectivity problems in directed graphs and, in particular, we consider the computation of the following natural relation: We say that two vertices v and w are 2-edge-connected if there are two edge-disjoint paths from v to w and two edge-disjoint paths from w to v. This relation partitions the vertices into blocks such that all vertices in the same block are 2-edge-connected. Differently from the undirected case, those blocks do not correspond to the 2-edge-connected components of the graph. We show how to compute this relation in linear time so that we can report in constant time if two vertices are 2-edge-connected. We also show how to compute in linear time a sparse certificate for this relation, i.e., a subgraph of the input graph that has O(n) edges and maintains the same 2-edge-connected blocks as the input graph.

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2-Connectivity in Directed Graphs: An Experimental Study

2015 Proceedings of the Seventeenth Workshop on Algorithm Engineering and Experiments (ALENEX), 2014

Dominator Certification and Independent Spanning Trees: An Experimental Study

Lecture Notes in Computer Science, 2013

Loop Nesting Forests, Dominators, and Applications

Lecture Notes in Computer Science, 2014

Probabilistic Inference in the Physical Simulation of Interdependent Critical Infrastructure Systems

Lecture Notes in Computer Science, 2014

Portraying algorithms with leonardo web

Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 2005

In this paper we describe our own experience in preparing animated presentations of computer scie... more In this paper we describe our own experience in preparing animated presentations of computer science concepts with Leonardo Web, a Java-based animation system that we have previously developed. Our discussion is aimed at highlighting how different visualization tools and techniques turned out to be useful in realizing effective Web-based teaching material. Our experience culminated in the preparation of an on-line repository of animated illustrations for a textbook on algorithms and data structures edited by McGraw-Hill in 2004. ⋆

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Visual editing of animated algorithms: The leonardo web builder

Proceedings of the Workshop on Advanced Visual Interfaces, 2006

Leonardo Web is a collection of tools to animate algorithms. Animations can be generated with a v... more Leonardo Web is a collection of tools to animate algorithms. Animations can be generated with a visual editor or directly as a trace of an algorithm's execution. They can be visualized via a small Java player, available as an applet or as a standalone application; the player supports bidirectional continuous and step-by-step execution. Furthermore the system allows to export the animations in several formats, including Macromedia Flash, Microsoft PowerPoint and animated GIF.

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Real-time anomalies detection and analysis of network structure, with application to the Autonomous System network

IWCMC 2011 - 7th International Wireless Communications and Mobile Computing Conference, 2011

Abstract The structural analysis is the very basic tool for understanding the properties of a net... more

Performance evaluation of algorithms for newspaper article identification

Proceedings of the International Conference on Document Analysis and Recognition, ICDAR, 2011

A typical modern newspaper recognition system operates in distinct phases: i) page segmentation (... more A typical modern newspaper recognition system operates in distinct phases: i) page segmentation (also called page decomposition or zoning), that is the process of decomposing a page into its structural and logical units (called regions or zones); ii) region (or zone) labeling, where the previously identified units are labeled according to their types (title, text, images, and lines); iii) article identification (or tracking or clustering), in which all the units that belong to a single article are clustered together; and iv) read order identification, in which each item in an article is assigned its reading order inside the article.

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