ABSTRACT
In several nominal and verbal ablauts, there is a key distinction between triliteral and longer (mostly quadriliteral) input stems. Full V's {i au} count for purposes of this calculation, but schwa and short tl do not. Triliteral stems may be strong (CC;JC or C;JCC), weak (CClI), hollow (CVC), or geminate (C;JCxCx), and stems of these types can require different ablaut patterns (e.g. PI of nouns, verbal noun of verbs). For quadriliterals it is usually sufficient to distinguish strong (C-final) from weak (V-final) stems, and even this distinction has little effect on the ablaut system.
