Normally, 'irregularity' in the popular idea of linguistics consists of patterns in morphology that don't hold. I have, for some time, been interested in other kinds of irregularities, such as quirky case.
Let's consider something in the ballpark of transitivity or valency. Of course, a simple way of creating irregularity for valency would be valency-marking on verbs, and then having a few verbs that deviate from the pattern. But then we're back in the irregular morphology rut again.
We could do another thing:
Have certain unmarked valency-changing operations occur under some circumstances, but have irregularities in this application for some particular verbs.
What kinds of circumstances could these be?
- Subjects (or possibly objects) of certain noun classes
- Subclauses vs. main clauses
- Specific types of subclauses
- Infinites vs. finite verbs?
- Certain TAMs?
- Certain voice, valency, transitivity or subcategorization changes
- Presence of certain adverbs?
- Certain word order changes?
- Under certain pragmatic conditions?
- Utterance-initial sentences? Discourse-initial sentences?