I have asked a similar question, but this problem (see the title) always confuses me. For example, suppose I introduced several symbols (e.g., A, B, and C) in my writing. In a later section, when I reuse the symbols in the same way, which one (or neither) is more appropriate?
The interpretation of the symbols follows that described above.
The interpretations of the symbols follow those described above.
Each symbol has its unique interpretation and thus there are multiple interpretations, so I think the latter is correct. But interpretation (or definition) is a shared property (although each has a different interpretation) so can it be singular? (e.g., cats have a nose.)