It would be equally valid to assume that John was not in the photograph.

The man in the picture is the man with the telescope that John saw.

Of course, if the only context is a photograph, then a perl based text manipulating program won't have access to that context, so saying that the program failed to disambiguate the text is wrong.

Another human being who cannot see the photograph would be similarly unable to perform the impossible.

True.

Interestingly, I did a small test on Microsoft Grammatic Check a few years ago to see how it works. I gave the following two sentences:

(1) He drives to work yesterday.

(2) Mary was attacked by a dog.

No complaints about (1) but an advisory to change (2) to the active.

I didn't have to do any more test :)

I don't have the latest Microsoft Word now. Otherwise, I'll be curious to see if things have changed.

It's all an evil conspiracy to keep English class in public school. I say "good!" for defective grammar checkers, all the sooner than can be removed. Maybe we can teach kids to do Algebra without graphing calculators too...