Open Access

RelHunter: a machine learning method for relation extraction from text

  • Eraldo R. Fernandes1Email author,
  • Ruy L. Milidiú1 and
  • Raúl P. Rentería2
Journal of the Brazilian Computer Society201016:18

Received: 8 February 2010

Accepted: 16 July 2010

Published: 8 August 2010


We propose RelHunter, a machine learning-based method for the extraction of structured information from text. RelHunter’s key idea is to model the target structures as a relation over entities. Hence, the modeling effort is reduced to the identification of entities and the generation of a candidate relation, which are simpler problems than the original one. RelHunter fits a very broad spectrum of complex computational linguistic problems. We apply it to five tasks: phrase chunking, clause identification, hedge detection, quotation extraction, and dependency parsing. We compare RelHunter to token classification approaches through several computational experiments on seven multilingual corpora. RelHunter outperforms the token classification approaches by 2.14% on average. Moreover, we compare the derived systems against state-of-the-art systems for each corpus. Our systems achieve state-of-the-art performances for three corpora: Portuguese phrase chunking, Portuguese clause identification, and English quotation extraction. Additionally, the derived systems show good quality performance for the other four corpora.


Natural language processing Entity relation extraction Machine learning Entropy Guided Transformation Learning