I am reposting this because I did not receive an answer and am still stuck.

Question

I am reposting this because I did not receive an answer and am still stuck.

(a) The lexicon and phrase structure grammar cannot provide
hierarchical structures (i.e., trees) for sentences such as the following:
-A lion escaped from the zoo yesterday.
-An eagle flew away quickly.
State additions to the lexicon and grammar that will provide complete trees for these
sentences, and draw the two trees.1

(c) For each of the following sentences, indicate whether it has a complete hierarchical structure according to the revised lexicon and grammar (yes/no).
-A cute lion escaped from the zoo yesterday.
-An cute lion escaped from the zoo yesterday.
-A gray eagle flew away quickly.
-An gray eagle flew away quickly.

(d) Suppose we would like to modify the lexicon and grammar so that the ungrammatical sentences above do not have complete tree structures. Could we do this by only splitting each of the syntactic categories Determiner and Noun into two subcategories and revising the
phrase structure rules that refer to Determiner and Noun? (explain why or why not)

Answer 1

You undoubtedly got no reply because there are no linguistics experts on this website. Sorry.

Answer 2

To provide complete trees for the sentences given in question (a), we need to make additions to both the lexicon and the grammar.

For the first sentence "A lion escaped from the zoo yesterday," we need to add the word "escaped" as a verb to the lexicon. Additionally, we need to modify the phrase structure grammar to account for the verb phrase "escaped from the zoo." Here's the modified grammar:

Lexicon additions:
- escaped (Verb)

Grammar additions:
S -> NP VP
VP -> V PP
PP -> P NP

Tree for "A lion escaped from the zoo yesterday":
```
S
/ \
NP VP
| / \
Det V PP
| | / \
A escaped P NP
| |
from Det
|
the
|
zoo
```

For the second sentence "An eagle flew away quickly," we again need to add "flew" as a verb to the lexicon. Here's the modified grammar:

Lexicon additions:
- flew (Verb)

Grammar additions:
S -> NP VP

Tree for "An eagle flew away quickly":
```
S
/ \
NP VP
| |
Det V
| |
An flew
|
PP
/ \
P Adv
| |
away quickly
```

Moving on to question (c), let's determine whether the given sentences have a complete hierarchical structure according to the revised lexicon and grammar.

- "A cute lion escaped from the zoo yesterday."
Yes, this sentence has a complete hierarchical structure.

- "An cute lion escaped from the zoo yesterday."
No, this sentence does not have a complete hierarchical structure because "cute" is not a valid determiner in English.

- "A gray eagle flew away quickly."
Yes, this sentence has a complete hierarchical structure.

- "An gray eagle flew away quickly."
No, this sentence does not have a complete hierarchical structure because "gray" is not a valid determiner in English.

Lastly, let's address question (d) regarding modifying the lexicon and grammar to make the ungrammatical sentences lack complete tree structures.

No, splitting the syntactic categories Determiner and Noun into two subcategories and revising the phrase structure rules will not achieve the desired effect. The problems with the ungrammatical sentences "An cute lion escaped from the zoo yesterday" and "An gray eagle flew away quickly" arise from the choice of determiners, not the structure of the noun phrase. Simply splitting the categories or revising the phrase structure rules without addressing the specific issues of the determiners will not resolve the problem.