Σ

Σ

1. (mathematics) Σ. Sum over a set of like terms:

   ${\displaystyle \sum _{n=1}^{2}n^{2}=1^{2}+2^{2}=5}$

2. (topology) suspension or reduced suspension
3. (mathematics) A class (in the arithmetical hierarchy) of formulae whose outermost unbounded quantifiers are existential quantifiers

(mathematics): Though there exists a distinct symbol (∑) for the purpose of the mathematical summation, the upper case sigma here is often used for convenience.

• (classification of formulae): Π, Δ

• Σ on Wikipedia.Wikipedia

Σ • (S) (uppercase, lowercase σ)

1. The upper case letter sigma (σίγμα), the 18th letter of the modern Greek alphabet.

Σ • (S)

1. The number 200 in Greek numerals.

,Σ

1. The number 200,000 in Greek numerals.

see: Appendix:Greek alphabet