I'm reading Syntax of the Comparative Clause Construction in English by Joan W. Bresnan. The author says:
The comparative clause construction in English is almost notorious for its syntactic complexity.
What accounts for the fact that in (A), (i) and (ii) can be read as (roughly) synonymous, while (iii) and (iv) cannot?
A I. I've never seen a man taller than my father.
II. I've never seen a taller man than my father.
lll. I've never seen a man taller than my mother.
IV. *I've never seen a taller man than my mother.
Why does (iv) depart from grammaticality in (B)?
B I. Jack eats caviar more than he eats mush.
II. Jack eats more caviar than he eats mush.
lll. Jack eats caviar more than he sleeps.
IV. *Jack eats more caviar than he sleeps.
What explains the ungrammaticality of (Civ)?
C I. I am more angry today than I was yesterday.
II. I am angrier today than I was yesterday.
lll. I am more angry than sad.
IV. *I am angrier than sad.
For what reason is (iii) so much less acceptable than (iv) in (D) ?
D i. Mary is more than six feet tall.
ii. Mary is taller than six feet.
iii. * Mary is more than five feet short.
IV. Mary is shorter than five feet.
Even after I digested the author's dissertation I couldn't understand the answers to those questions except the A, where the permutation of taller implies the anomaly that my mother is a man. What is compared in A(IV) is how tall a man my mother is. This is ok, I understand it.
According to the author's analyse in B the ungrammaticality is related to the transitivity of the verb sleep, but I don't see how this fact affects the grammar of the sentence.
I see C the most incomprehensible.
Regarding D, the author says:
To understand the ungrammaticality of D(iii), we must note that certain adjectives, including "privative" adjectives like short, do not admit modifiers of definite measurement, but these adjectives do permit comparison: He's less short than I thought.
Please let me know your thoughts on this.