I know cybalist has dealt with this topic before (e.g. message #44128), but I have not found any satisfactory answer to the question, what is the origin of vrddhi in denominal derivatives in Sanskrit? How could e.g. graiva- arise from gri:va:, or sauma- from soma-? Piotr has mentioned "e-insertion" into the main syllable, but this would not explain forms like graiva-, and does not explain why the process of "e-insertion" should arise in the first place.
I hope that someone would care to respond to this question once again. I want to know how "legitimate" vrddhi in denominals is (as well as other forms with vrddhi).
Andrew