An introduction to the principal mathematical models of sentence structure used in computational linguistics today. Topics include: string matching and similarity, string and tree transducers, extended context-free formalisms, tree-adjoining grammar, substructural logics, discourse representation calculi, typed feature structures, and topological models. Parsing, algorithmic complexity, algebraic properties, and formal equivalence will be discussed. A basic knowledge of logic, formal language theory, and graph theory is required. Some familiarity with syntactic theory will be helpful, but is not assumed.