A sole sufficient operator or a sole sufficient connective is an operator that is sufficient by
itself to define all of the operators in a specified set of operators.
In logical contexts this refers to a logical operator that suffices to define all of the boolean-valued
functions, f : X → 𝔹, where X is an arbitrary set and where 𝔹 is a generic 2-element set, typically
𝔹 = {0, 1} = {false, true}, in particular, to define all of the finitary boolean functions,
f : 𝔹k → 𝔹.
