 A long-standing issue in linguistic semantics has been the theoretical status of thematic roles in the  argument structure of verbs and other argument-taking elements of language (e.g., Dowty 1991). The syntactically marked cases found in many languages correspond intuitively to such thematic roles as agent, theme, patient, instrument, recipient, goal, and so on, and in English, too, the sentence subject and object typically correspond respectively to the agent and theme or patient of an action, and other roles may be added as an indirect object or more often as prepositional phrase complements and adjuncts. To give formal expression to these intuitions, many computational linguists decompose verbal (and other) predicates derived from language into a core predicate augmented with explicit binary relations representing thematic roles. For example, the sentence