What exactly does the term nucleus refer to in syntax? (I'm not asking about the term in relation to phonetics or phonology).
For example when syntacticians write about left dislocations and so forth they talk about the nucleus of the clause. Similarly in some grammars when talking about free relatives or fused relative constructions people sometime refer to the wh- word as the prenucleus.
Whilst I have a vague intuitive understanding of this term, I don't actually know what it means and haven't been able to find out from the web.
I'd like to know, for example, whether in English sentences with fronted negative adverbials, whether the negative word is occurring before the nucleus of the sentence. For example in the sentences:
- Never before have I been so embarrassed.
- Never have I been so embarrassed.
Do the items never or never before occur before the nucleus of the sentence?