  Different analytic notions of contextuality fall into two major groups:
probabilistic and strong notions of contextuality. Kochen and Specker's
Theorem~0 is a demarcation criterion for differentiating between those groups.
Whereas probabilistic contextuality still allows classical models, albeit with
nonclassical probabilities, the logico-algebraic "strong" form of contextuality
characterizes collections of quantum observables that have no faithfully
embedding into (extended) Boolean algebras. Both forms indicate a classical in-
or under-determination that can be termed "value indefinite" and formalized by
partial functions of theoretical computer sciences.
