The sentence 'I saw the man with the telescope' has two distinct interpretations. In constituent tree notation, how is this structural ambiguity represented?
AOne tree, with the word 'with' marked as lexically ambiguous
BTwo trees with identical structures but different word labels at the PP node
CTwo trees in which the PP 'with the telescope' attaches to different nodes — either inside the VP or inside the NP
DOne tree with a dotted edge showing the optional attachment of 'with the telescope'
Structural ambiguity arises from different constituency structures, not from ambiguous words. In reading 1 (you used the telescope to see), the PP 'with the telescope' attaches inside the VP as a modifier of the verb 'saw.' In reading 2 (the man had the telescope), the PP attaches inside the NP 'the man with the telescope.' These are two different trees with different dominance relations — the same string of words, two distinct hierarchical structures. This is exactly why formal notation is useful: it makes the source of the ambiguity explicit and unambiguous.
Question 2 Multiple Choice
A student argues: 'Bracket notation like [S [NP the cat] [VP sat]] is just shorthand for the tree diagram; the tree diagram shows more information because you can see the hierarchy visually.' This claim is:
ACorrect — tree diagrams encode dominance relations that linear brackets cannot express
BIncorrect — both representations encode exactly the same structural information; visual clarity differs but information content is identical
DIncorrect — bracket notation is actually more expressive because it specifies word order more precisely
Tree diagrams and bracket notation are equivalent representations — they are two different notations for the same formal object. Every dominance relation visible in the tree is encoded in the nesting structure of the brackets, and vice versa. The labels on nodes appear as labels inside brackets. The branching structure appears as nesting depth. A skilled linguist reads structural information from bracket notation just as efficiently as from a tree. The student confuses visual ease of reading with information content.
Question 3 True / False
Structural ambiguity in a sentence occurs when one or more of the words in the sentence has multiple meanings.
TTrue
FFalse
Answer: False
That describes lexical ambiguity, not structural ambiguity. Structural ambiguity arises when a single string of words — with all words having fixed, unambiguous meanings — can be assigned two distinct constituent structures (trees). 'I saw the man with the telescope' is structurally ambiguous because the PP can attach in two different places in the hierarchy; neither 'saw,' 'man,' nor 'telescope' is ambiguous as a word. The two readings come from different tree structures, not from different word meanings.
Question 4 True / False
In a constituent tree, if node A dominates node B, then the phrase represented by A contains the phrase represented by B as a part.
TTrue
FFalse
Answer: True
Dominance is the formal representation of structural containment. If NP dominates Det and N, then the noun phrase contains the determiner and noun. If S dominates NP and VP, then the sentence contains the noun phrase and the verb phrase. This is what makes trees useful: the hierarchy of domination relationships directly encodes which phrases are parts of which larger phrases, something that a flat sequence of words cannot capture.
Question 5 Short Answer
Why is formal tree notation particularly useful for analyzing structural ambiguity, compared to describing the ambiguity in prose?
Think about your answer, then reveal below.
Model answer: Formal trees make ambiguity precise and visible. A prose description can gesture at two readings ('he used the telescope' vs. 'the man had the telescope'), but it cannot pinpoint the structural source of the difference. Two trees with different attachment sites for the PP show exactly which grouping differs — and make it clear that the ambiguity is structural, not lexical. Trees also enable systematic comparison: any two readings of an ambiguous sentence are represented as two distinct formal objects that can be analyzed, compared, and used computationally.
Prose explanations are circular: 'it can mean X or Y' just restates the ambiguity without explaining it. Trees explain it by showing the two different structures that give rise to the two meanings. This is why formal notation is not just convenient but epistemically superior for syntactic analysis — it forces precision about what the structural options actually are and excludes hand-waving.