UPC-CORE : What can machine translation evaluation metrics and Wikipedia do for estimating semantic textual similarity?

In this paper we discuss our participation to the 2013 Semeval Semantic Textual Similarity task. Our core features include (i) a set of metrics borrowed from automatic machine translation, originally intended to evaluate automatic against reference translations and (ii) an instance of explicit semantic analysis, built upon opening paragraphs of Wikipedia 2010 articles. Our similarity estimator relies on a support vector regressor with RBF kernel. Our best approach required 13 machine translation metrics + explicit semantic analysis and ranked 65 in the competition. Our postcompetition analysis shows that the features have a good expression level, but overfitting and —mainly— normalization issues caused our correlation values to decrease.