𝟙

𝟙 U+1D7D9, 𝟙 MATHEMATICAL DOUBLE-STRUCK DIGIT ONE ← 𝟘 [U+1D7D8] Mathematical Alphanumeric Symbols 𝟚 → [U+1D7DA]

Translingual

Symbol

𝟙

1. (mathematics) indicator function

Usage notes

The corresponding set is usually denoted by a subscript: 𝟙_A.

Synonyms

• (indicator function): 𝟏, χ, I