منابع مشابه
Conservative Median Algebras and Semilattices
We characterize conservative median algebras and semilattices by means of forbidden substructures and by providing their representation as chains. Moreover, using a dual equivalence between median algebras and certain topological structures, we obtain descriptions of the median-preserving mappings between products of finitely many chains.
متن کاملEmbedding Median Algebras in Products of Trees
We show that a metric median algebra satisfying certain conditions admits a bilipschitz embedding into a finite product of R-trees. This gives rise to a characterisation of closed connected subalgebras of finite products of complete R-trees up to bilipschitz equivalence. Spaces of this sort arise as asymptotic cones of coarse median spaces. This applies to a large class of finitely generated gr...
متن کاملA duality for isotropic median algebras
We establish categorical dualities between varieties of isotropic median algebras and suitable categories of operational and relational topological structures. We follow a general duality theory of B.A. Davey and H. Werner. The duality results are used to describe free isotropic median algebras. If the number of free generators is less than five, the description is detailed.
متن کاملArrow type impossibility theorems over median algebras
We characterize trees as median algebras and semilattices by relaxing conservativeness. Moreover, we describe median homomorphisms between products of median algebras and show that Arrow type impossibility theorems for mappings from a product A1 ˆ ̈ ̈ ̈ ˆ An of median algebras to a median algebra B are possible if and only if B is a tree, when thought of as an ordered structure.
متن کاملSome Basics on Tolerances
In this paper we deal with sensitivity analysis of combinatorial optimization problems and its fundamental term, the tolerance. For three classes of objective functions (Σ,Π,MAX) we give some basic properties on upper and lower tolerances. We show that the upper tolerance of an element is well defined, how to compute the upper tolerance of an element, and give equivalent formulations when the u...
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ژورنال
عنوان ژورنال: Czechoslovak Mathematical Journal
سال: 1983
ISSN: 0011-4642,1572-9141
DOI: 10.21136/cmj.1983.101885