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We identify and validate from a large corpus constraints from conjunctions on the positive or negative semantic orientation of the conjoined adjectives. A log-linear regression model uses these constraints to predict whether conjoined adjectives are of same or different orientations, achieving 82% accuracy in this task when each conjunction is considered independently. Combining the constraints across many adjectives, a clustering algorithm separates the adjectives into groups of different orientations, and finally, adjectives are labeled positive or negative. . | Predicting the Semantic Orientation of Adjectives Vasileios Hatzivassiloglou and Kathleen R. McKeown Department of Computer Science 450 Computer Science Building Columbia University New York N.Y. 10027 USA vh kathy cs.Columbia.edu Abstract We identify and validate from a large corpus constraints from conjunctions on the positive or negative semantic orientation of the conjoined adjectives. A log-linear regression model uses these constraints to predict whether conjoined adjectives are of same or different orientations achieving 82 accuracy in this task when each conjunction is considered independently. Combining the constraints across many adjectives a clustering algorithm separates the adjectives into groups of different orientations and finally adjectives are labeled positive or negative. Evaluations on real data and simulation experiments indicate high levels of performance classification precision is more than 90 for adjectives that occur in a modest number of conjunctions in the corpus. 1 Introduction The semantic orientation or polarity of a word indicates the direction the word deviates from the norm for its semantic group or lexical field Lehrer 1974 . It also constrains the word s usage in the language Lyons 1977 due to its evaluative characteristics Battistella 1990 . For example some nearly synonymous words differ in orientation because one implies desirability and the other does not e.g. simple versus simplistic . In linguistic constructs such as conjunctions which impose constraints on the semantic orientation of their arguments Anscombre and Ducrot 1983 Elhadad and McKeown 1990 the choices of arguments and connective are mutually constrained as illustrated by The tax proposal was simple and well-received simplistic but well-received simplistic and well-received J by the public. In addition almost all antonyms have different semantic orientations.1 If we know that two words relate to the same property for example members of the same scalar group such .
