The Dual in Tocharian

Within the historical phonology of Tocharian, the elucidation of special
phonological developments in word-final position, or Auslautgesetze,
faces several well-known obstacles. Relatively few inflectional
endings in Tocharian have unambiguous Proto-Indo-European
sources, and of those, even fewer have a well-understood prehistory;
even such a basic set of morphemes as the person-number endings of the present/subjunctive poses a number of as yet unsolved puzzles. The situation is even worse in the noun, where, due to extensive remodeling of the inherited PIE system of nominal inflection and derivation, it is often difficult to identify appropriate comparanda for Tocharian nominal forms and to distinguish the effects of regular sound change from the workings of analogy. Finally, since the Proto- Tocharian nonhigh vowels *-a, *-ë, *-e, *-o were all lost in Tocharian A, only Tocharian B provides evidence for those vowels in word-final position.