Contraction Anchors
Contraction anchors (high-value contractions)
-άω: α + ο/ω -> ω; α + ε/η -> α -έω: ε + ε -> ει; ε + ο -> ου; ε + long vowel usually disappears into the long vowel -όω: ο + ε/η -> ου; ο + ο/ω -> ου/ω; ο + ει -> οι
Source: Morphology sheet, p. 20.