The central research questions of linguistic semantics include the nature of meaning and the human knowledge of meaning, the relations of meaning to linguistic form (both in the lexicon and in the combination of phrases), and the interaction between form and context in ongoing linguistic communication. Forming the basis for research at USC and elsewhere, it is supposed that meaning is closely related to conditions on truth known to native speakers. One asks of a human language how a speaker grasps the truth conditions of its linguistic structures, or given assumptions about the meaning, what is the nature of the structures triggering these meanings. USC faculty with a primary interest in semantics or pragmatics include Elena Guerzoni, James Higginbotham, Elsi Kaiser, Roumyana Pancheva and Barry Schein, whose research interests have included negative expressions and interrogatives; tense and aspect; anaphora and pronouns; demonstrative and indexical reference and definite description; plurals and reciprocals; conjunctive, conditional, comparative and relative clauses; and the syntax and semantics of reference to events. In recent years, semantics has acquired a comparative dimension, raising questions about linguistic variation, especially at the interface between syntax and semantics. USC benefits from the presence of a comparative syntax group, among which are - Hagit Borer, Hajime Hoji, Audrey Li, Andrew Simpson - and Maria Luisa Zubizarreta. The Center for the Linguistics/Philosophy Interface is a forum for research on meaning under the joint auspices of the Department of Linguistics and the School of Philosophy. Affiliated faculty from the School of Philosophy and those with a research interest in semantics or philosophy of language include Stephen Finlay, James Higginbotham, Robin Jeshion, Shieva Kleinschmidt, Karen Lewis, Jacob Ross, Mark Schroeder, Scott Soames, Gabriel Uzquiano Cruz, and George Wilson.