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?