\dblcolonThe \dblcolon command in LaTeX is used to denote a relation that is visually represented by two colons. It is often used in mathematical expressions to signify a specific type of mapping or relation between elements, similar to a function or a transformation.
A relation from set A to set C through B
A \dblcolon B \to CA mapping of element x to element y by function f
f \dblcolon x \mapsto yA chained relation involving sets X, Y, and Z
X \dblcolon Y \dblcolon Z