dblcolon

Represents a double colon operator commonly used in mathematical logic and set theory for formal definitions and relations.

Overview

Serves as a specialized punctuation mark in mathematical writing to indicate formal definitions, type declarations, or precise semantic relationships between mathematical objects.

Frequently used in type theory to separate variables from their types
Common in formal logic for expressing definitional equality
Appears in computer science literature when describing formal specifications
Provides a more formal alternative to the single colon when extra precision is needed

Examples

Defining a type signature in mathematical logic or computer science notation.

f \dblcolon X \to Y

f \dblcolon X \to Y

Expressing a relation between sets in category theory.

F \dblcolon \mathcal{C} \to \mathcal{D}

F \dblcolon \mathcal{C} \to \mathcal{D}

Denoting a typing judgment in programming language theory.

e \dblcolon \text{Int} \to \text{Bool}

e \dblcolon \text{Int} \to \text{Bool}