A rule that converts every sentence with a given constituent structure into a new sentence with derived constituent structure, related in a fixed way to the original. Rules like affix hopping and the passive are transformations, beyond phrase structure.
By a restricting class R (the sequences \(X_1, \ldots, X_r\) a string with its phrase marker must be analysable into, e.g. NP, Auxiliary, V, NP for the passive) and an elementary transformation \(t\) (the structural change made to the analysed parts).
The set of strings occurring as lines in a maximal set of equivalent derivations of a sentence; a string has more than one phrase marker iff it has nonequivalent derivations.
What is the tripartite structure of a transformational grammar?
Phrase-structure rules produce a terminal string; transformations give morphemes in the correct order; morphophonemic rules (have + past → had, take + ing → taking) give phonemes.
Distinguish obligatory and optional transformations, and define the kernel.
Obligatory ones (like affix hopping) must apply or the result isn’t grammatical; optional ones (like the passive) may or may not. Kernel sentences are derived from phrase-structure strings by obligatory transformations only; all others come from optional transformations.
What did Chomsky find about the kernel of English?
The grammar is greatly simplified if the kernel is a very small set of simple, active, declarative sentences (probably finite), with questions, passives, conjunctions and complex noun phrases derived by transformations, which can compound (e.g. questions from passives).
Why might kernel sentences be the “content elements” of understanding?
Transformations are by and large meaning-preserving, so the kernel sentences underlying a sentence can be seen as the elementary content elements in terms of which the actual (usually complicated) transform is understood.
In what sense is a transformational grammar still an elementary finite-state process?
Each transformation is finitely characterizable, and its restricting class bounds how much information about a string (how much derivation history) is needed to apply it; more than the last line must be inspected, but still a bounded amount.