منابع مشابه
Homomorphisms and amalgamation
We prove that for each ,nite core graph G, the class of all graphs admitting a homomorphism into G is a pseudo-amalgamation class, in the sense of Fra01ss2 e. This fact gives rise to a countably in,nite universal pseudo-homogeneous graph which shares some of the properties of the in,nite random graph. Our methods apply simultaneously to G-colourings in several classes of relational structures, ...
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Let $f:Arightarrow B$ and $g:A rightarrow C$ be two ring homomorphisms and let $J$ and $J^{'}$ be two ideals of $B$ and $C$, respectively, such that $f^{-1}(J)=g^{-1}(J^{'})$. The bi-amalgamation of $A$ with $(B,C)$ along $(J,J^{'})$ with respect of $(f,g)$ is the subring of $Btimes C$ given by $Abowtie^{f,g}(J,J^{'})={(f(a)+j,g(a)+j^{'})/ a in A, (j,j^{'}) in Jtimes J^{'}}.$ In ...
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We describe the major result on categoricity in Lω1,ω , placing it in the context of more general work in abstract elementary classes. In particular, we illustrate the role of higher dimensional amalgamations and sketch the role of a weak extension of ZFC in the proof. We expound the translation of the problem to studying atomic models of first order theories. We provide a simple example of the...
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Theorem. For each 2 ≤ k < ω there is an Lω1,ω-sentence φk such that: (1) φk is categorical in μ if μ ≤ אk−2; (2) φk is not אk−2-Galois stable; (3) φk is not categorical in any μ with μ > אk−2; (4) φk has the disjoint amalgamation property; (5) For k > 2, (a) φk is (א0,אk−3)-tame; indeed, syntactic first-order types determine Galois types over models of cardinality at most אk−3; (b) φk is אm-Gal...
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We present a property of neat reducts commuting with forming subalgebras as a definability condition. The purpose of this paper is to relate results on neat reducts, a notion particular to cylindric algebras to results on the “more universal” strong amalgamation property in a very general setting. It is known [7], [8] and [6] that amalgamation properties in a class of algebras correspond to int...
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ژورنال
عنوان ژورنال: Discrete Mathematics
سال: 2003
ISSN: 0012-365X
DOI: 10.1016/s0012-365x(02)00864-6