There is a natural map which assigns to every model U of type τ, (U ε Stτ) a group G (U) in such a way that elementarily equivalent models are mapped into isomorphic groups. G(U) is a subset of a collection whose members are called Fraisse arrows (they are decreasing sequences of sets of partial isomorphisms) and which arise in connection with the Fraisse characterization of elementary equivalence. Let EC λ U be defined as {U εStr τ: ℬ ≡U and |ℬ|=λ; then EG λ U can be faithfully (i.e. 1-1) represented onto G(U) ×π *, where π *, is a collection of partitions over λ∪λ2∪....
A group-theoretical invariant for elementary equivalence and its role in representations of elementary classes / D.MUNDICI. - In: STUDIA LOGICA. - ISSN 0039-3215. - STAMPA. - 40:(1981), pp. 253-267. [10.1007/BF02584060]
A group-theoretical invariant for elementary equivalence and its role in representations of elementary classes
MUNDICI, DANIELE
1981
Abstract
There is a natural map which assigns to every model U of type τ, (U ε Stτ) a group G (U) in such a way that elementarily equivalent models are mapped into isomorphic groups. G(U) is a subset of a collection whose members are called Fraisse arrows (they are decreasing sequences of sets of partial isomorphisms) and which arise in connection with the Fraisse characterization of elementary equivalence. Let EC λ U be defined as {U εStr τ: ℬ ≡U and |ℬ|=λ; then EG λ U can be faithfully (i.e. 1-1) represented onto G(U) ×π *, where π *, is a collection of partitions over λ∪λ2∪....I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.