\BbbkThe command \Bbbk is used in LaTeX to represent a blackboard bold lowercase 'k', often used to denote a field, such as the field of scalars in algebraic structures.
Vector space of dimension n over the field \Bbbk
V = \Bbbk^nPolynomial ring over the field \Bbbk
\Bbbk[x]Characteristic of the field \Bbbk is zero
\text{char}(\Bbbk) = 0