What is the meaning of σ?
Braid group algebra.
a labialized alveolar fricative (value uncertain, possibly IPA [θʷ]).
The Stefan-Boltzmann constant.
Lower-case sigma (σίγμα), the 18th letter of the ancient Greek alphabet. It represented the voiceless alveolar fricative /s/. It is preceded by ρ and followed by τ.
The lower case letter sigma (σίγμα), the 18th letter of the modern Greek alphabet.
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