What does this sentence mean?

What does the following sentence mean to you?

1) I saw the man with a telescope.

Which of the following meanings did you get?

1a) With a telescope, I saw the man.
1b) The man had a telescope and I saw him.

Both readings are reasonably possible, so sentences such as (1) above are said to be syntactically, or structurally, ambiguous because they can be interpreted in more than one way as a result of different underlying structures.

The ambiguity arises because the prepositional phrase with a telescope can modify either the verb saw or the noun phrase the man. Visually, the two possible readings can be represented in tree diagrams:

Reading 1a

Reading 1b

(The tree diagrams were drawn using the software at http://mshang.ca/syntree/)

Structurally ambiguous sentences are not ungrammatical, but they can csuse unnecessary confusion and misinterpretation.

The following is an example of an ambiguous sentence I came across recently:

ChannelNewsAsia - 21 March 2013

The intended meaning is sentence (2a) below:

(2a) To prepare for the meeting, Obama's national security advisor Tom Donilon would go to Beijing on May 26-28.

But the sentence could also have the meaning (2b):

(2b) The meeting is scheduled for May 26-28 and Obama's national security advisor Tom Donilon would go to Beijing to prepare for it.