Do Reduplication With Phonological Processes?

In Proto Indo European, they permitted nasals and resonance to be a syllable nuclei. But by the time you got degree, Greek said, no. And N, syllabic N and syllabic M became the vowel. So that's how ancient Greek created the perfect is the initial consonant plus epsilon. It had a small number of verbs whose present stems also had reduplication, but they used a different vowel.