First conjugation??

[Nico60]

Hi everyone! I've just started studying a linguistics module at uni and am a bit stuck with one of my tutor's sentences on their lecture sheet:

"As with verbs, there is an idiosyncratic relationship between the root and the choice of theme vowel, although the only productive one nowadays is the one corresponding to the first conjugation:
chat-e-a-r
person-a-r-se
presupuest-a-r"

- In what way is there an idiosyncratic relationship between the root and the theme vowel?
- What does the tutor mean by "productive" here?
- What is the "first conjugation"?

Apologies for all the questions!  Just trying to get my head around it all.  Thanks!

[Audiendus]

- In what way is there an idiosyncratic relationship between the root and the theme vowel?
- What does the tutor mean by "productive" here?
- What is the "first conjugation"?

I am not a linguistics expert, and I cannot answer your first question, but:

1. "First conjugation" in Spanish refers to verbs ending in -ar in the infinitive.
2. I presume that "productive" means that it is capable of forming new verbs.
3. I presume that the "theme vowel" in -ar verbs is a, which also occurs in many other parts of such verbs.