منابع مشابه
Congruence Classes in Brouwerian Semilattices1
Brouwerian semilattices are meet-semilattices with 1 in which every element a has a relative pseudocomplement with respect to every element b, i. e. a greatest element c with a∧c ≤ b. Properties of classes of reflexive and compatible binary relations, especially of congruences of such algebras are described and an abstract characterization of congruence classes via ideals is obtained.
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We consider a combinatorial problem motivated by a special simplified timetabling problem for subway networks. Mathematically the problem is to find (pairwise) disjoint congruence classes modulo certain given integers; each such class corresponds to the arrival times of a subway line of a given frequency. For a large class of instances we characterize when such disjoint congruence classes exist...
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Let A = (A;F ) be an algebra and ConA its congruence lattice. Recall that A is congruence uniform (see e.g. [1], [5]) if for each Θ ∈ ConA and every a, b ∈ A, card[a]Θ = card[b]Θ. Examples of congruence uniform algebras are e.g. groups, rings or Boolean algebras. A variety V is congruence uniform if each A ∈ V has this property. It was proved by W. Taylor [5] that every congruence uniform varie...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2000
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(99)00366-0