I was writing down some mathematical notes and encountered a grammatical intuition that confused me.
- “X, which is the bound given in (1.2), and which is sharp” sounds fine;
- “X, which is the bound given in (1.2), and is sharp” sounds weird;
- “X, which is the bound given in (1.2), and sharp” sounds awful.
I understand why the last one sounds awful; the two verbs, one of which expresses an identity and one a quality, aren’t parallel, despite looking the same. (I guess you could say ‘It depends what the meaning of the word “is” is.’) But why does the second one sound funny? Or am I wrong, and the first two both sound funny? And why does Larkin’s roughly equivalent formulation sound fine?
The parallelism in #1 is between two relative clauses: “X, which p, and which q”. #2 attempts to conjoin a relative clause “which p” with a verb phrase “q”, which doesn’t work. #3 puts both into the same relative clause, but attempts to conjoin the noun “bound” with the adjective “sharp”. That doesn’t work either.
“Match parts!”
Try #2 without the comma:
“X, which is the bound given in (1.2) and is sharp”
This sounds fine to me: there are two parallel verb phrases inside the “which”.
Assuming the actual sentence went on further, perhaps we’re trying to say too much in one sentence.
I think the problem may be too many words.
“X, the bound given in (1.2), is sharp.”
I agree with JmSR; the commas in the original phrase can be smoothly replaced with parentheses without changing the meaning. So the rule of thumb is to drop the entire phrase surrounded by the commas and check that what’s left makes sense. This would leave you with:
1) X and which is sharp
2) X and is sharp
3) X and sharp
Clearly the “and” is wrong here, and you want number 2 (to get X…is sharp)
Are you a Larkin fan?
Who isn’t?