He was working by himself without a supervisor to notify approaching train operators.
Can we use a to-infinitive as a postmodifier after supervisor?
and do it have ambiguity? i mean his job is to notify approaching train operators.
He was working by himself without a supervisor to notify approaching train operators.
Can we use a to-infinitive as a postmodifier after supervisor?
and do it have ambiguity? i mean his job is to notify approaching train operators.
Yes. It would be very important to note that "to-infinitive" works as an adjective that postmodifies the noun that precedes it.
Let's compare these two sentences:
He didn't have any supervisor to notify her. (simplified version of your example)
He didn't have any book to read.
The two sentences have the same construction, subject + transitive verb (have) + object (supervisor, book) + to infinitive. The two sentences could be rephrased to:
- He didn't have any supervisor who (that) could notify her.
- He didn't have any book which (that) he could read.
Now, you can see both to-infinitives and relative clauses postmodify the preceding nouns. Your example sentence could be rephrased to:
He was working by himself without any supervisor who could notify approaching train operators.
Of course, there could be ambiguity if you read the sentence without any context. For example, your sentence could be rephrased to the following if you consider "to infinitive" as an adverbial phrase that indicates "purpose" of an action "to work".
The purpose of him working alone without a supervisor was (so as) to notify approaching train operators.
This could mean that the presence of a supervisor could have been a factor that could prevent him from notifying approaching train operators. But, how likely is it to be interpreted that way? I don't think it is very likely that it could be interpreted that way.