 Thus, the theory does not dispute that the present of the PIE 3rd conjugation is related to the traditional middle and perfect endings, it just moves the common ancestry back to a time before that of PIE proper.In his thesis on Hittite, Alwin Kloekhorst has shown that the "ḫi"-conjugation of that language is virtually the same as the reconstructed perfect (or stative) of Proto-Indo-European, but without any reduplication.In a more recent study, Olivier Simon demonstrates that in the oldest stage of Proto-Indo-European, the active stative was unreduplicated (as in the Hittite "ḫi"-conjugation or in the widely accepted reconstruction of "*woidh₂e" = "I know") while the medio-passive was reduplicated (as shown by old Greek and Sanskrit irregular perfects), and therefore unifies the Hittite "ḫi"-conjugation with the Proto-Indo-European mainstream model.