Minimal ring extensions of the integers exhibiting Kochen–Specker contextuality

This paper is a contribution to the algebraic study of contextuality in quantum theory. As an algebraic analogue of Kochen and Specker’s no-hidden-variables result, we investigate rational subrings over which the partial ring of [Formula: see text] symmetric matrices ([Formula: see text]) admits no morphism to a nonzero commutative ring, which we view as an “algebraic hidden state”. For [Formula: see text], the minimal such ring is shown to be [Formula: see text], while for [Formula: see text] the minimal subring is [Formula: see text] itself. The proofs rely on the construction of new sets of integer vectors in dimensions 3 and 6 that have no Kochen–Specker coloring.