While doing some final testing on fronting languages, I noticed some problems in my treatment of optional pied piping. Specifically I was not covering determiner extraction from subjects:
(1) какой приехал человек? which arrived person? `Which person arrived?' [rus]
This was because the basic-head-subject phrase was not allowing slashed non-head daughters. Relaxing this constraint requires instead constraining subject-head, so that there isn’t ambiguity in sentences like (2):
(2) какой человек приехал? which person arrived? `Which person arrived?' [rus]
Similarly it is tempting to constrain complement-head (to insist on slash-empty non-head-daughters), to avoid ambiguity in sentences like (3):
Какой сон видит Иван? which dream sees Ivan `What dream is Ivan seeing?' [rus]
However, I then lose (4):
(4) Сколько Иван книг читает? how.many Ivan books reads `How many books is Ivan reading?' [rus]
So it looks like generally, the solution is not the right one.
It sounds like this may be similar to the problems we were solving for the head-adjunct and the in-situ rules.
I wonder if I can apply a similar solution here? Any thoughts?