منابع مشابه
Singular Covers in Free Lattices
A covering a > b in a lattice is called a singular cover if a is join irreducible and b is meet irreducible. A classification of the singular covers which occur in free lattices is given. AMS (MOS) subject classification (1980). 06B25.
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A bidouble cover is a nite at Galois morphism with Galois group (Z=2) 2 ?. The structure theorem for smooth Galois (Z=2) 2 ? covers was given in Cat2] pag. 491-493] where bidouble covers of P 1 P 1 were introduced in order to nd interesting properties of the moduli spaces of surfaces of general type. In this paper we develop general formulae for the case of resolutions of singular bidouble cove...
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Ralph Freese Department of Mathematics University of Hawaii at Manoa Honolulu, Hawaii 96822 In this paper we look at some of the problems on free lattices and free modular lattices which are of an order theoretic nature. We review some of the known results, give same new results, and present several open problems. Every countable partially ordered set can be order embedded into a countable free...
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For an arbitrary graph G = (V,E), let X be a graphical property that can be possessed, or satisfied by the subsets of V . For example, being a clique (maximal complete subgraph), a maximal independent set, an edge, a closed neighborhood, a minimal dominating set, etc. Let CX ={A|A ⊆ V , |A| > 1, and A possesses or satisfies property X}. A set S is an X cover (or X free) if A ∩ S (or A ∩ (V − S)...
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ژورنال
عنوان ژورنال: Order
سال: 1986
ISSN: 0167-8094,1572-9273
DOI: 10.1007/bf00403408