Am I analyzing this sentence in syntax correctly?
I don't know how many books you've sold.
S = NP + VP
NP = I
VP = VP(1) + NP(1)
VP(1) = [don't [know]] (don't is a pre-string that modifies the main verb know)
NP(1) = [how many [books] (that) you've sold] (how many is a pre-string and you've sold is a relative clause as a post-string that modify the main noun books)
Is this correct?
JukerlawVP(1) = [don't [know]] (don't is a pre-string that modifies the main verb know)
I have never encountered that terminology!
The verbs do, have and be are auxiliary verbs, so I would analyze your main clause as
I = subject
do know = verb phrase, consisting of the lexical verb is know, and the auxiliary, do. The auxiliary is required for negation, since lexical verbs are not directly negated in English syntax.
https://www.thoughtco.com/what-is-a-lexical-verb-1691228
https://www.thoughtco.com/nice-properties-verbs-1691346
Not is an adverb.
I thought every Phrase Type has 3 main parts that are Pre-string - Head - Post-string.
Prepositional phrases do not have that structure. The head word is the preposition and it comes first, is followed by a complement, most commonly a noun phrase.
https://learnenglish.britishcouncil.org/en/english-grammar/prepositional-phrases
Verb phrases do not have that structure.
Noun phrases can have that structure: premodifiers, head noun, postmodifiers.
Read this: https://learnenglish.britishcouncil.org/en/english-grammar/noun-phrase
Premodifiers can be determiners, quantifiers or adjective phrases.
Postmodifiers can be clauses, prepositional phrases, and (rarely) adjectives and
Thank you. I'll research more about this.