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A. I bought a robot cleaner to clean my house when I'm not at home.

1. Is sentence A correct English?
2. What is "to clean my house" referring to? I or a robot cleaner?

3. Can an infinitive phrase like "to clearn my house" be grammatically used for modifying the direct object of a main verb in a sentence when the infinitive phrase doesn't refer to the subject like in A?

One more example,

B. Will you introduce someone to help me now?

Here, the infinitive phrase "to help me now" refers/modifies someone, not refer to you,

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[1] I bought a robot cleaner [ ____ to clean my house when I'm not at home].

The bracketed element is an infinitival relative clause modifying "robot cleaner". The relativised element, represented by gap '____', is subject of the relative clause and understood as "robot cleaner".


[2] Will you introduce someone [ ____ to help me now]?

Again, the infinitival is a relative clause, here modifying "someone". The relativised element is subject of the relative clause and understood as "someone".


The fact that the matrix (main) clause subjects are not the same as those of the infinitivals is not significant.



Comments  

I'm not qualified to answer these questions. But I think that the first one is obvious.

"I bought a robot cleaner to clean my house when I'm not at home."

Read the whole sentence and you will realize easily who was intended. If you were not at home, who would clean your house?

The robot.

Originally, why did you buy a robot?

To clean your house when you're not at home.

If you were not at home, how could you clean your house? Is it possible to clean it yourself?

No, and that's why you bough a robot.

 BillJ's reply was promoted to an answer.