a number of different lexical categories, and each instance of the symbol ′ stands for a bar. So A′, for instance, would be a kind of AP (adjective phrase). Two bars, used here for the complements, is thought by some linguists to be a maximal projection of a lexical category. Such a schema is meant to be combined with specific lexical rules and the projection principle to distinguish the various patterns of specific verbs. Head-driven phrase structure grammar (HPSG) introduces a handful of such schemata which aim to subsume all such valence related rules as well as other rules not related to valence. A network is developed for information related to specific lexical items. The network and one of the schemata aims to subsume the large number of specific rules defining the valence of particular lexical items. Notice that the rule (VP → H NP [love]) and the schema (X′ → X, Y″...) deal only with non-subject complements. This is because all of the above syntactic frameworks use a totally separate rule (or schema) to introduce the subject. This is a major difference between them and Tesnière's original understanding of valency, which included the subject, as mentioned above. One of the most widely known versions of construction grammar (CxG) also treats the subject like other complements, but this may be because the emphasis is more on semantic roles and compatibility with work in cognitive science than on syntax. See also Argument Arity Case grammar Dependency grammar Grammatical conjugation Lucien Tesnière Morphosyntactic alignment Phrase structure grammar Subcategorization Transitivity Verb Notes References Allerton, D. J. 1982. Valency and the English verb. London: Academic Press. Chomsky, N. 1965. Aspects of the theory of syntax. Cambridge, Massachusetts: MIT Press. Chomsky, N. 1981. Lectures on Government and Binding. Dordrecht: Foris. de Groot, A. W. 1949. Structurele Syntaxis. Den Haag: Servire. Fischer, K. and V. Ágel. 2010. Dependency grammar and valency theory. In: The Oxford handbook of linguistic analysis, 223–255. Oxford: Oxford University Press. Gazdar, G., E. Klein, G. Pullum, and I. Sag. 1984. Generalized Phrase Structure Grammar. Oxford: Basil Blackwell. Goldberg, A. E. 1995. Constructions: A Construction Grammar approach to argument structure. Chicago: University of Chicago Press. Haspelmath, Martin & Thomas Müller-Bardey. (2000). Valence change. In G. Booij, C. Lehmann, & J. Mugdan. (Eds.). Morphology: An International Handbook on Inflection and Word-Formation. Berlin, Germany: Walter de Gruyter. Hockett, C. F. (1958). A Course in Modern