Over on the fqxi forum
http://fqxi.org/community/forum/topic/812, some of us were earlier discussing the elephant in the room which the small but real discrepancies between these various attempts to simulate Joy's model seem to have introduced.
But is there an elephant in the room? Since all these various simulations come very close to the cosine curve, who cares? They all exhibit resounding violation of the CHSH inequality... (By the way, *only* the Gisin and Gisin model hits it exactly. That can be proven analytically for Gisin and Gisin, and statistically - five standard deviations good enough for you? It was good enough for the Higgs Boson - for all the others). See
http://rpubs.com/gill1109 and
http://rpubs.com/chenopodium for proofs.
The problem is in the heart of the simulation. In order to generate outcomes for A and B (or in Chantal's model, A times B) we need values of the settings a and b, and we need a realization of the hidden state lambda.
In both simulations, lambda is effectively generated by the rejection method: an initial randomization can generate both states lambda and non-states (points lambda outside of the domain of A(a, .) and B(b, .)). So we just keep picking a lambda from the big set of states and non-states, till we are lucky to get a state.
In both simulation models, the criterion for rejection depends on a and b. In other words, the domain of the hidden state and hence also its probabilty distribution, depends on a and b.
Maybe this only appears to be so? Maybe if you have checked some criterion involving a and b is satified, then it is also satisfied for all possible a' and all possible b', hence it not actually "measurement setting dependent"? Well, that is what Joy claims, but the fact of the matter is that Bell's theorem shows that this selection *must* be measurement setting dependent. You can only violate Bell's inequality by violating one of locality, realism, or no-conspiracy. In this case the simulation is evidently local realist. So it violates "no-conspiracy", aka "freedom".
Either the original S^3 Joy's model is wrong, or the deductions from that model to the simulation models are wrong.
In my opinion, the real elephant in the room is the attempt to simulate Christian's mathematics within the confines of local realism on classical computers. That enterprise is doomed to failure ... by Bell's theorem. Earlier, Joy always admitted this. He always said: you have to *circumvent* Bell. He then did a U-turn and is now suffering the dire consequences.
Joy's model cannot be reproduced in flatland. It needs a real physical S^3. It needs a kind of Möbius strip in space-time which alters the measurement outcomes (the measurement outcomes which Alice and Bob saw and collected in their respective labs) as they bring them back in their space-ships, from their labs on distant planets on distant galaxies, back to Christian's head office on Planet Earth.