Relations between Bell's inequality and noncommutativity of operators
are discussed via the four operators involved in the Clauser et al ine
quality. The case of all operators commuting (i.e. the six commutators
vanish) and the case of three out of the four operators mutually comm
uting (i.e. five commutators vanish) is shown to abide by the inequali
ty. In the latter case a novel insight is unravelled. The Bell quantum
bound (2 root 2) is obeyed for the case when four commutators vanish.
The probabilistic upper limit of the inequality is reviewed and shown
to be 4. In any theory based on Hilbert space, the upper limit is 2 r
oot 3.