I was trying to enforce that the predicate _grass_n_1 be a mass noun only so I don’t generate things like “the grasses.”
I can just constrain it to singular, but I think that prevents things like “I like grass.”
I tried to add [ IND - ] to it, but then it won’t generate anything. @ebender suggested that I can’t just add [ IND - ] to any predicate, and there needs to be a corresponding entry for _grass_n_1 with [ IND - ] on the index in the grammar.
Is this the case or is there some other way around this?
It should be fine to constrain the index to be singular for mass nouns. If you parse “I like grass.” you’ll see that the resulting MRS has “NUM sg” for the ARG0 of the EP for “grass”, and indeed the generator is happy with that input.
While you might logically expect to be able to add “IND -” to the index for “grass”, the generator fails because when the SEMI is constructed, it reflects the fact that “grass” can be used either as a mass noun or as a count noun, so the only SEMI entry for “grass” leaves the value of IND underspecified. When you try adding “IND -” to the input to the generator, you make it impossible for the generator to match this constraint in its output, since it uses the (only) lexical entry for “grass”, which fails (by design) to give any value for “IND”. In contrast, you’ll see that the SEMI entry for “rice” specifies “IND -” since “rice” only has a mass noun lexical entry, so adding “IND -” to the ARG0 for “rice” in the input MRS for the generator succeeds.