𝟏

𝟏 U+1D7CF, 𝟏 MATHEMATICAL BOLD DIGIT ONE ← 𝟎 [U+1D7CE] Mathematical Alphanumeric Symbols 𝟐 → [U+1D7D0]

Translingual

Alternative forms

• 𝟙

Symbol

𝟏

1. (mathematics, set theory) The indicator function of a set.

Usage notes

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

Synonyms

• (indicator function): χ, I