Mathematics equivalent to Bell's derivation of the inequalities, also allows a local hidden variables explanation for the correlation between distant measurements.
Bell inequalities exclude a broad class of local hidden-variable explanations of quantum correlations. A recurring objection is that the usual Bell form is static, whereas real measuring devices may contain local memory, stochastic dynamics, and measurement-induced disturbances of their hidden variables. We formulate this objection as a general transition-kernel model for dynamical hidden variables. The only locality assumption is imposed at the ontic level: conditional on the pre-measurement ontic state, the transition kernel and response function in each wing depend on the local setting but not on the distant setting or on distant post-measurement variables. Under measurement independence, all such dynamics can be absorbed into effective local response functions. The resulting probabilities have exactly the static Bell-local form and therefore obey the CHSH inequality. The result identifies the available escape routes for reproducing quantum correlations: violating ontic dynamical locality, violating measurement independence, or abandoning a classical hidden-variable ontology. As a consequence, local classical dynamical complexity cannot by itself spoof Bell-nonlocal statistics in device-independent protocols.
The Bell theorem is explored in terms of a trade-off relation between underlying assumptions within the hidden variable model framework. In this paper, recognizing the incorporation of hidden variables as one of the fundamental assumptions, we propose a measure termed `hidden information' taking account of their distribution. This measure quantifies the number of hidden variables that essentially contribute to the empirical statistics. For factorizable models, hidden variable models that satisfy `locality' without adhering to the measurement independence criterion, we derive novel relaxed Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequalities. These inequalities elucidate trade-off relations between measurement dependence and hidden information in the CHSH scenario. It is also revealed that the relation gives a necessary and sufficient condition for the measures to be realized by a factorizable model.