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Publications

Publications by CRACS

2012

Interactive visualization of a news clips network: A journalistic research and knowledge discovery tool

Authors
Devezas, J; Figueira, A;

Publication
KDIR 2012 - Proceedings of the International Conference on Knowledge Discovery and Information Retrieval

Abstract
Interactive visualization systems are powerful tools in the task of exploring and understanding data. We describe two implementations of this approach, where a multidimensional network of news clips is depicted by taking advantage of its community structure. The first implementation is a multiresolution map of news clips that uses topic detection both at the clip level and at the community level, in order to assign labels to the nodes in each resolution. The second implementation is a traditional force-directed network visualization with several additional interactive aspects that provide a rich user experience for knowledge discovery. We describe a common use case for the visualization systems as a journalistic research and knowledge discovery tool. Both systems illustrate the links between news clips, induced by the co-occurrence of named entities, as well as several metadata fields based on the information contained within each node. Copyright © 2012 SciTePress - Science and Technology Publications.

2012

Supervising and managing projects through a template based e-portfolio system

Authors
Felix, C; Figueira, A;

Publication
CSEDU 2012 - Proceedings of the 4th International Conference on Computer Supported Education

Abstract
We report an integration process that involves the Moodle learning management system and an in-house developed e-portfolio system - SPD - and the institution information system. SPD is a system developed to create, evaluate and maintain digital portfolios assigned and assessed by a jury to keep a high quality level of the projects registered. The SPD system uses information imported from Moodle's database, in order to fill in its own database for users and courses and for propagating the existing session between systems. It also keeps projects ordered by development phases, determining whatever can be done and by whom, making them available for consult only after being accepted by the jury. To aid the rapid creation of projects and development of its documentation a set of pre-defined templates are made available.

2012

Finding language-independent contextual supernodes on coreference networks

Authors
Devezas, J; Figueira, A;

Publication
IAENG International Journal of Computer Science

Abstract
We propose a method for creating news context by taking advantage of a folksonomy of web clipping based on online news. We experiment with an ontology-based named entity recognition process, describing two alternate implementation approaches, and we study two different ways of modeling the relationships induced by the coreference of named entities on news clips. We try to establish a context by identifying the community structure for a clip-centric network and for an entity-centric network, based on a small test set from the Breadcrumbs system. Finally, we compare both models, based on the detected news communities, and show the advantages of each network specilication.

2012

Comparison of co-authorship networks across scientific fields using motifs

Authors
Choobdar, S; Ribeiro, P; Bugla, S; Silva, F;

Publication
2012 IEEE/ACM INTERNATIONAL CONFERENCE ON ADVANCES IN SOCIAL NETWORKS ANALYSIS AND MINING (ASONAM)

Abstract
Comparing scientific production across different fields of knowledge is commonly controversial and subject to disagreement. Such comparisons are often based on quantitative indicators, such as papers per researcher, and data normalization is very difficult to accomplish. Different approaches can provide new insight and in this paper we focus on the comparison of different scientific fields based on their research collaboration networks. We use co-authorship networks where nodes are researchers and the edges show the existing co-authorship relations between them. Our comparison methodology is based on network motifs, which are over represented patterns, or subgraphs. We derive motif fingerprints for 22 scientific fields based on 29 different small motifs found in the corresponding co-authorship networks. These fingerprints provide a metric for assessing similarity among scientific fields, and our analysis shows that the discrimination power of the 29 motif types is not identical. We use a co-authorship dataset built from over 15,361 publications inducing a co-authorship network with over 32,842 researchers. Our results also show that we can group different fields according to their fingerprints, supporting the notion that some fields present higher similarity and can be more easily compared.

2012

A design and implementation of the Extended Andorra Model

Authors
Lopes, R; Costa, VS; Silva, F;

Publication
THEORY AND PRACTICE OF LOGIC PROGRAMMING

Abstract
Logic programming provides a high-level view of programming, giving implementers a vast latitude into what techniques to explore to achieve the best performance for logic programs. Towards obtaining maximum performance, one of the holy grails of logic programming has been to design computational models that could be executed efficiently and that would allow both for a reduction of the search space and for exploiting all the available parallelism in the application. These goals have motivated the design of the Extended Andorra Model (EAM), a model where goals that do not constrain nondeterministic goals can execute first. In this work, we present and evaluate the Basic design for EAM, a system that builds upon David H. D. Warren's original EAM with Implicit Control. We provide a complete description and implementation of the Basic design for EAM System as a set of rewrite and control rules. We present the major data structures and execution algorithms that are required for efficient execution, and evaluate system performance. A detailed performance study of our system is included. Our results show that the system achieves acceptable base performance and that a number of applications benefit from the advanced search inherent to the EAM.

2012

Querying subgraph sets with g-tries

Authors
Pinto Ribeiro, PM; Silva, FMA;

Publication
Proceedings of the 2nd ACM SIGMOD Workshop on Databases and Social Networks, DBSocial 2012, Scottsdale, AZ, USA, May 20, 2012

Abstract
In this paper we present an universal methodology for finding all the occurrences of a given set of subgraphs in one single larger graph. Past approaches would either enumerate all possible subgraphs of a certain size or query a single subgraph. We use g-tries, a data structure specialized in dealing with subgraph sets. G-Tries store the topological information on a tree that exposes common substructure. Using a specialized canonical form and symmetry breaking conditions, a single non-redundant search of the entire set of subgraphs is possible. We give results of applying g-tries querying to different social networks, showing that we can efficiently find the occurrences of a set containing subgraphs of multiple sizes, outperforming previous methods. Copyright 2012 ACM.

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