David Martins de Matos

Improving a hybrid literary book recommendation system through author ranking

Literary reading is an important activity for individuals and can be a long term commitment, making book choice an important task for book lovers and public library users. In this paper, we present a hybrid recommendation system to help readers decide which book to read next. We study book and author recommendations in a hybrid recommendation setting and test our algorithm on the LitRec data set. Our hybrid method combines two item-based collaborative filtering algorithms to predict books and authors that the user will like. Author predictions are expanded into a booklist that is subsequently aggregated with the former book predictions. Finally, the resulting booklist is used to yield the top-n book recommendations. By means of various experiments, we demonstrate that author recommendation can improve overall book recommendation.

Extractive summarization of broadcast news: comparing strategies for European portuguese

This paper presents the comparison between three methods for extractive summarization of Portuguese broadcast news: feature-based, Maximal Marginal Relevance, and Latent Semantic Analysis. The main goal is to understand the level of agreement among the automatic summaries and how they compare to summaries produced by non-professional human summarizers. Results were evaluated using the ROUGE-L metric. Maximal Marginal Relevance performed close to human summarizers. Both feature-based and Latent Semantic Analysis automatic summarizers performed close to each other and worse than Maximal Marginal Relevance, when compared to the summaries done by the human summarizers.

Self reinforcement for important passage retrieval

In general, centrality-based retrieval models treat all elements of the retrieval space equally, which may reduce their effectiveness. In the specific context of extractive summarization (or important passage retrieval), this means that these models do not take into account that information sources often contain lateral issues, which are hardly as important as the description of the main topic, or are composed by mixtures of topics. We present a new two-stage method that starts by extracting a collection of key phrases that will be used to help centrality-as-relevance retrieval model. We explore several approaches to the integration of the key phrases in the centrality model. The proposed method is evaluated using different datasets that vary in noise (noisy vs clean) and language (Portuguese vs English). Results show that the best variant achieves relative performance improvements of about 31% in clean data and 18% in noisy data.

BioBlaze: Multi-core SIMD ASIP for DNA sequence alignment

A new Application-Specific Instruction-set Processor (ASIP) architecture for biological sequences alignment is proposed in this manuscript. This architecture achieves high processing throughputs by exploiting both fine and coarse-grained parallelism. The former is achieved by extending the Instruction Set Architecture (ISA) of a synthesizable processor to include multiple specialized SIMD instructions that implement vector-vector and vector-scalar arithmetic, logic, load/store and control operations. Coarse-grained parallelism is achieved by using multiple cores to cooperatively align multiple sequences in a shared memory architecture, comprising proper hardware-specific synchronization mechanisms. To ease the programming, a compilation framework based on an adaptation of the GCC back-end was also implemented. The proposed system was prototyped and evaluated on a Xilinx Virtex-7 FPGA, achieving a 200MHz working frequency. A sequential and a state-of-theart SIMD implementations of the Smith-Waterman algorithm were programmed in both the proposed ASIP and an Intel Core i7 processor. When comparing the achieved speedups, it was observed that the proposed ISA achieves a 40x speedup, which contrasts with the 11x speedup provided by SSE2 in the Intel Core i7 processor. The scalability of the multi-core system was also evaluated and proved to scale almost linearly with the number of cores.

Stylometric relevance-feedback towards a hybrid book recommendation algorithm

Reading is an important activity for individuals. Content-based recommendation systems are, typically, used to recommend scientific papers or news, where search is driven by topic. Literary reading or reading for leisure differs from scientific reading, because users search books not only for their topic but also by author or writing style. Choosing a new book to read can be tricky and recommendation systems can make it easy by selecting books that the user will like. In this paper we study recommendation through writing style and the influence of negative examples in user preferences. Our experiments were conducted in a hybrid set-up that combines a collaborative filtering algorithm with stylometric relevance feedback. Using the LitRec data set, we demonstrate that writing style influences book selection; that book content, characterized with writing style, can be used to improve collaborative filtering results; and that negative examples do not improve final predictions.

Key Phrase Extraction of Lightly Filtered Broadcast News

This paper explores the impact of light filtering on automatic key phrase extraction (AKE) applied to Broadcast News (BN). Key phrases are words and expressions that best characterize the content of a document. Key phrases are often used to index the document or as features in further processing. This makes improvements in AKE accuracy particularly important. We hypothesized that filtering out marginally relevant sentences from a document would improve AKE accuracy. Our experiments confirmed this hypothesis. Elimination of as little as 10% of the document sentences lead to a 2% improvement in AKE precision and recall. AKE is built over MAUI toolkit that follows a supervised learning approach. We trained and tested our AKE method on a gold standard made of 8 BN programs containing 110 manually annotated news stories. The experiments were conducted within a Multimedia Monitoring Solution (MMS) system for TV and radio news/programs, running daily, and monitoring 12 TV and 4 radio channels.

Multiple Hypothesis Tracking in camera networks

In this paper we address the problem of tracking multiple targets across a network of cameras with non-overlapping fields of view. Existing methods to measure similarity between detected targets and the ones previously encountered in the network (the re-identification problem) frequently produce incorrect correspondences between observations and existing targets. We show that these issues can be corrected by Multiple Hypothesis Tracking (MHT), using its capability of disambiguation when new information is available. MHT is recognized in the multi-target tracking field by its ability to solve difficult assignment problems. Experiments both in simulation and in real world present clear advantages when using MHT with respect to the simpler MAP approach.

On the application of generic summarization algorithms to music

Several generic summarization algorithms were developed in the past and successfully applied in fields such as text and speech summarization. In this paper, we review and apply these algorithms to music. To evaluate their performance, we adopt an extrinsic approach: we compare a Fado genre classifiers performance using truncated contiguous clips against the summaries extracted with those algorithms on two different datasets. We show that Maximal Marginal Relevance (MMR), LexRank, and Latent Semantic Analysis (LSA) all improve classification performance in both datasets used for testing.

Improving idsay: a characterization of strengths and weaknesses in question answering systems for Portuguese

IdSay is a Question Answering system for Portuguese that participated at QA@CLEF 2008 with a baseline version (IdSayBL). Despite the encouraging results, there was still much room for improvement. The participation of six systems in the Portuguese task, with very good results either individually or in an hypothetical combination run, provided a valuable source of information. We made an analysis of all the answers submitted by all systems to identify their strengths and weaknesses. We used the conclusions of that analysis to guide our improvements, keeping in mind the two key characteristics we want for the system: efficiency in terms of response time and robustness to treat different types of data. As a result, an improved version of IdSay was developed, including as the most important enhancement the introduction of semantic information. We obtained significantly better results, from an accuracy in the first answer of 32.5% in IdSayBL to 50.5% in IdSay, without degradation of response time.

Mixed-Source Multi-Document Speech-to-Text Summarization

Speech-to-text summarization systems usually take as input the output of an automatic speech recognition (ASR) system that is affected by issues like speech recognition errors, disfluencies, or difficulties in the accurate identification of sentence boundaries. We propose the inclusion of related, solid background information to cope with the difficulties of summarizing spoken language and the use of multi-document summarization techniques in single document speech-to-text summarization. In this work, we explore the possibilities offered by phonetic information to select the background information and conduct a perceptual evaluation to better assess the relevance of the inclusion of that information. Results show that summaries generated using this approach are considerably better than those produced by an up-to-date latent semantic analysis (LSA) summarization method and suggest that humans prefer summaries restricted to the information conveyed in the input source.