Abstract
The elements of a relation algebra A that are below a fixed elementa form a relative subalgebrab Aa of A. It was shown by H. Andréka that the class of all relative subalgebras of relation algebras is not a variety, but it follows immediately from results of R. L. Kramer that the closure of this class under subalgebras is a finitely based variety. We show that the relative subalgebras A0′ with 0′ the diversity element of A, form a finitely based variety. We also show that A is determined by A0′, up to a direct factor that is Boolean (the relative product coincides with the meet).
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References
Andréka, H., OnTaking Subalgebras of Relativized Relation Algebras, Algebra Universalis25 (1988), 96–100.
Chin, L. H. andTarski, A.,Distributive and Modular Laws in Relation Algebras, Univ. of Calif. Publ. in Math. N.S.1 (1951), 341–383.
Jónsson, B.,Varieties of Relation Algebras, Algebra Universalis15 (1982), 273–298.
Jónsson, B.,A Survey of Boolean Algebra with Operators, inAlgebras and Orders, NATO ASI Series C: Mathematical and Physical Sciences, Vol, 389, Kluwer Academic Publishers (1993), 239–286.
Jónsson, B. andTarski, A.,Boolean Algebras with Operators I, Amer. J. Math73 (1951), 891–939.
Jónsson, B. andTarski, A.,Boolean Algebras with Operators II, Amer. J. Math.74 (1952), 127–162.
Jónsson, B. andTsinakis, C.,Relation Algebras as Residuated Boolean Algebras, Algebra Universalis30 (1993), 469–478.
Kramer, R. L.,Relativized Relation Algebras, inAlgebraic Logic (Proc. Conf. Budapest 1988, ed. by H. Andréka, J. D. Monk and I. Németi). Colloq. Math. Soc. J. Bolyai, Vol. 54, North-Holland, Amsterdam (1991), 671–693.
Lyndon, R.,Relation Algebras and Projective Geometries, Michigan Math. J.8 (1961), 21–28.
Maddux, R.,Some Varieties Containing Relation Algebras, Transactions of the AMS272 No. 2 (1982), 501–526.
McKenzie, R., McNulty, G. andTaylor, W.,Algebras, Lattices, Varieties, Wadsworth and Brooks/Cole, Monterey, CA, 1987.
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Rafter, J. Relativizations of relation algebras by the diversity. Algebra Universalis 35, 342–358 (1996). https://doi.org/10.1007/BF01197179
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DOI: https://doi.org/10.1007/BF01197179