Thesaurus based automatic keyphrase indexing

We propose a new method that enhances automatic keyphrase extraction by using semantic information on terms and phrases gleaned from a domain-specific thesaurus. We evaluate the results against keyphrase sets assigned by a state-of-the-art keyphrase extraction system and those assigned by six professional indexers

Thesaurus-based index term extraction for agricultural documents

This paper describes a new algorithm for automatically extracting index terms from documents relating to the domain of agriculture. The domain-specific Agrovoc thesaurus developed by the FAO is used both as a controlled vocabulary and as a knowledge base for semantic matching. The automatically assigned terms are evaluated against a manually indexed 200-item sample of the FAO’s document repository, and the performance of the new algorithm is compared with a state-of-the-art system for keyphrase extraction

Coherent Keyphrase Extraction via Web Mining

Keyphrases are useful for a variety of purposes, including summarizing, indexing, labeling, categorizing, clustering, highlighting, browsing, and searching. The task of automatic keyphrase extraction is to select keyphrases from within the text of a given document. Automatic keyphrase extraction makes it feasible to generate keyphrases for the huge number of documents that do not have manually assigned keyphrases. A limitation of previous keyphrase extraction algorithms is that the selected keyphrases are occasionally incoherent. That is, the majority of the output keyphrases may fit together well, but there may be a minority that appear to be outliers, with no clear semantic relation to the majority or to each other. This paper presents enhancements to the Kea keyphrase extraction algorithm that are designed to increase the coherence of the extracted keyphrases. The approach is to use the degree of statistical association among candidate keyphrases as evidence that they may be semantically related. The statistical association is measured using web mining. Experiments demonstrate that the enhancements improve the quality of the extracted keyphrases. Furthermore, the enhancements are not domain-specific: the algorithm generalizes well when it is trained on one domain (computer science documents) and tested on another (physics documents).Comment: 6 pages, related work available at http://purl.org/peter.turney

Human-competitive automatic topic indexing

Topic indexing is the task of identifying the main topics covered by a document. These are useful for many purposes: as subject headings in libraries, as keywords in academic publications and as tags on the web. Knowing a document's topics helps people judge its relevance quickly. However, assigning topics manually is labor intensive. This thesis shows how to generate them automatically in a way that competes with human performance. Three kinds of indexing are investigated: term assignment, a task commonly performed by librarians, who select topics from a controlled vocabulary; tagging, a popular activity of web users, who choose topics freely; and a new method of keyphrase extraction, where topics are equated to Wikipedia article names. A general two-stage algorithm is introduced that first selects candidate topics and then ranks them by significance based on their properties. These properties draw on statistical, semantic, domain-specific and encyclopedic knowledge. They are combined using a machine learning algorithm that models human indexing behavior from examples. This approach is evaluated by comparing automatically generated topics to those assigned by professional indexers, and by amateurs. We claim that the algorithm is human-competitive because it chooses topics that are as consistent with those assigned by humans as their topics are with each other. The approach is generalizable, requires little training data and applies across different domains and languages

Indización automática de artículos científicos sobre Biblioteconomía y Documentación con SISA, KEA y MAUI

This article evaluates the SISA (Automatic Indexing System), KEA (Keyphrase Extraction Algorithm) and MAUI (Multi-Purpose Automatic Topic Indexing) automatic indexing systems to find out how they perform in relation to human indexing. SISA’s algorithm is based on rules about the position of terms in the different structural components of the document, while the algorithms for KEA and MAUI are based on machine learning and the statistical features of terms. For evaluation purposes, a document collection of 230 scientific articles from the Revista Española de Documentación Científica published by the Consejo Superior de Investigaciones Científicas (CSIC) was used, of which 30 were used for training tasks and were not part of the evaluation test set. The articles were written in Spanish and indexed by human indexers using a controlled vocabulary in the InDICES database, also belonging to the CSIC. The human indexing of these documents constitutes the baseline or golden indexing, against which to evaluate the output of the automatic indexing systems by comparing terms sets using the evaluation metrics of precision, recall, F-measure and consistency. The results show that the SISA system performs best, followed by KEA and MAUI.Este artículo evalúa los sistemas de indización automática SISA (Automatic Indexing System), KEA (Keyphrase Extraction Algorithm) y MAUI (Multi-Purpose Automatic Topic Indexing) para averiguar cómo funcionan en relación con la indización realzada por especialistas. El algoritmo de SISA se basa en reglas sobre la posición de los términos en los diferentes componentes estructurales del documento, mientras que los algoritmos de KEA y MAUI se basan en el aprendizaje automático y las frecuencia estadística de los términos. Para la evaluación se utilizó una colección documental de 230 artículos científicos de la Revista Española de Documentación Científica, publicada por el Consejo Superior de Investigaciones Científicas (CSIC), de los cuales 30 se utilizaron para tareas formativas y no formaban parte del conjunto de pruebas de evaluación. Los artículos fueron escritos en español e indizados por indizadores humanos utilizando un vocabulario controlado en la base de datos InDICES, también perteneciente al CSIC. La indización humana de estos documentos constituye la referencia contra la cual se evalúa el resultado de los sistemas de indización automáticos, comparando conjuntos de términos usando métricas de evaluación de precisión, recuperación, medida F y consistencia. Los resultados muestran que el sistema SISA funciona mejor, seguido de KEA y MAUI

Fusion architectures for automatic subject indexing under concept drift:Analysis and empirical results on short texts

Indexing documents with controlled vocabularies enables a wealth of semantic applications for digital libraries. Due to the rapid growth of scientific publications, machine learning-based methods are required that assign subject descriptors automatically. While stability of generative processes behind the underlying data is often assumed tacitly, it is being violated in practice. Addressing this problem, this article studies explicit and implicit concept drift, that is, settings with new descriptor terms and new types of documents, respectively. First, the existence of concept drift in automatic subject indexing is discussed in detail and demonstrated by example. Subsequently, architectures for automatic indexing are analyzed in this regard, highlighting individual strengths and weaknesses. The results of the theoretical analysis justify research on fusion of different indexing approaches with special consideration on information sharing among descriptors. Experimental results on titles and author keywords in the domain of economics underline the relevance of the fusion methodology, especially under concept drift. Fusion approaches outperformed non-fusion strategies on the tested data sets, which comprised shifts in priors of descriptors as well as covariates. These findings can help researchers and practitioners in digital libraries to choose appropriate methods for automatic subject indexing, as is finally shown by a recent case study

Penyaringan Frasa Kunci Secara Otomatis Menggunakan Algoritma Kea++ Untuk Pencarian Artikel Ilmiah Berbahasa Indonesia

Pencarian artikel ilmiah akan lebih mudah dengan adanya ikhtisar dari artikel ilmiah. Frasa kunci menyediakan ikhtisar ringkas mengenai artikel ilmiah. Meskipun frasa kunci sangat berguna, sebagian artikel ilmiah tidak memiliki frasa kunci. Penyaringan frasa kunci secara manual menghabiskan waktu dan cukup mahal. Penyaringan frasa kunci secara otomatis dapat menghemat waktu yang diperlukan untuk menentukan frasa kunci artikel ilmiah. Penelitian ini mengembangkan sistem pencarian artikel ilmiah berbahasa Indonesia yang memanfaatkan penyaringan frasa kunci artikel ilmiah berbahasa Indonesia menggunakan algoritma KEA++. Data yang digunakan dalam penelitian ini adalah 30 jurnal akuntansi berbahasa Indonesia dan Tesaurus akuntansi berbahasa Indonesia. Berdasarkan hasil pengujian, semakin banyak data pelatihan, akurasi penyaringan frasa kunci semakin baik. Hasil pengujian untuk penggunaan Tesaurus, nilai rata-rata precision dan recall yang diperoleh adalah 23.8% dan 37.4%. Berdasarkan penilaian dari responden untuk penilaian kinerja penyaringan frasa kunci, sistem memperoleh total skor 31 dari total skor memungkinkan 45 dan persentase frasa kunci yang sesuai adalah 51.75