1. Phrases Structure Rules (PS Rules): These rules govern the structure of phrases and sentences, specifying the grammatical categories and how they combine. They are hierarchical and recursive, allowing for the creation of complex sentences.
2. Transformational Rules: These rules operate on the output of PS rules, modifying the sentence structure to create different meanings or grammatical forms. They can change word order, add or delete elements, and perform other manipulations.
It's important to note that these two categories work in tandem. PS Rules generate the basic structure, while Transformational Rules fine-tune it to create variations and express different meanings.
The idea of "three kinds of rules" is not a standard concept in Transformational Grammar. However, one could argue that a third category exists:
3. Lexical Rules: These rules govern the insertion of specific words (lexemes) into the sentence structure. They determine the appropriate words based on the grammatical categories defined by PS Rules. While not explicitly stated as a separate category, the lexicon is an essential component of the grammar.
Ultimately, the key distinction lies in the way these rules function:
- PS Rules: Define the basic structure and categories.
- Transformational Rules: Modify the structure to achieve different meanings.
- Lexical Rules: Determine the specific words to be inserted.
So, while not strictly "three kinds," these three aspects of generative grammar work together to account for the complexity and variety of human language.