## Complemented tolerances on lattices.(English)Zbl 0536.06007

A tolerance relation on a lattice L is a reflexive symmetric binary relation T having the property that aTb, cTd together imply that $$(a\vee c)T(b\vee d)$$ and $$(a\wedge c)T(b\wedge d).$$ If the tolerance relations on L are partially ordered by set inclusion, they form a complete algebraic lattice called the tolerance lattice of L. The thrust of the paper is the proof of the assertion that if z,z’ are complementary elements of the bounded modular lattice L, and if T(0,z), T(0,z’) denote the minimal tolerance relations collapsing the quotients z/0, z’/0, then the following are equivalent: (a) z is central in L. (b) T(0,z) and T(0,z’) are complementary elements of the tolerance lattice of L.
Reviewer’s note: It is not difficult to show the result to be true for an arbitrary bounded lattice. The theorem is similar to a result of the reviewer on complemented congruences [Pac. J. Math. 73, 87-90 (1977; Zbl 0371.06005), p. 88].
Reviewer: M.F.Janowitz

### MSC:

 06B10 Lattice ideals, congruence relations 06C05 Modular lattices, Desarguesian lattices

Zbl 0371.06005
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