Overview
Sigma, the 18th letter of the Greek alphabet from ancient scripts like those influencing Phoenician and Latin, represents an 's' sound and has shaped mathematics via summation notation in works by Albert Einstein and Noam Chomsky discussions on linguistics. The Cyrillic alphabet, derived from Greek uncials by saints Cyril and Methodius for Old Church Slavonic, powers languages like Russian and Bulgarian, sharing letters like lunate sigma with Greek while adapting for Slavic phonetics amid influences from Glagolitic and Byzantine traditions.