phrase structure rule

PS-rule

in a TG grammar, a constituent (left side) followed by the sign for entailment, which is then followed by one or more constituents (right side), ¶4-4-2, cf. Backus-Naur Form in The Languages of Science; a partially ordered set of p. s. r. are the rules of formation, ¶8-1-6; a p. s. r. may include a description of the structural context which imposes a condition on its validity; a summary of p. s. r. for English syntax is listed below, cf. appendix B, ¶1