Boris Tsirelson,
"Noise as a Boolean algebra of sigma-fields. II. Classicality, blackness, spectrum"
arXiv:1109.1690.
Available online (free of charge) from e-print archive (USA):
arXiv.org/abs/1109.1690/
or its Israeli mirror:
il.arXiv.org/abs/1109.1690/

A research eprint, 13 pages, bibl. 7 refs.

Similarly to noises, Boolean algebras of sigma-fields can be black. A noise may be treated as a homomorphism from a Boolean algebra of regular open sets to a Boolean algebra of sigma-fields. Spectral sets are useful also in this framework.

1. Introduction.
1. Classicality and blackness.
2. Spectrum.
3. Digression: planar spectral sets, etc.