Abstract
LetL be a finite relational language andH(L) denote the class of all countable stableL-structuresM for which Th(M) admits elimination of quantifiers. ForM ∈H(L) define the rank ofM to be the maximum value of CR(p, 2), wherep is a complete 1-type over Ø and CR(p, 2) is Shelah’s complete rank. IfL has only unary and binary relation symbols there is a uniform finite bound for the rank ofM ∈H(L). This theorem confirms part of a conjecture of the first author. Intuitively it says that for eachL there is a finite bound on the complexity of the structures inH(L).
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References
G. Cherlin and A. H. Lachlan,Finitely homogeneous structures, typescript.
G. Cherlin, L. Harrington and A. H. Lachlan,ℵ 0-categorical ℵ0-stable structures, Ann. Pure Appl. Log., to appear.
R. Fraissé,Sur l’extension aux relations de quelques propriétés des ordres, Ann. Sci. École Norm. Sup.71 (1954), 361–388.
A. Gardiner,Homogeneous graphs, J. Comb. Theory, Ser. B20 (1976), 94–102.
A. H. Lachlan,Two conjectures on the stability of ω-categorical theories, Fund. Math.81 (1974), 133–145.
A. H. Lachlan,Finite homogeneous simple digraphs, Proceedings of the Herbrand Symposium, Logic Colloquium ’81 (J. Stern, ed.), North-Holland, Amsterdam, 1982, pp. 189–208.
A. H. Lachlan,On countable stable structures which are homogeneous for a finite relational language, Isr. J. Math.49 (1984), 69–153 (this issue).
S. Shelah,Classification Theory and the Number of Non-Isomorphic Models, North-Holland, Amsterdam, 1978.
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Dedicated to the memory of Abraham Robinson on the tenth anniversary of his death
This paper was conceived during the academic year 1980/81 while the authors were Fellows of the Institute for Advanced Studies of the Hebrew University of Jerusalem. The authors would like to thank the Institute for its generous support.
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Lachlan, A.H., Shelah, S. Stable structures homogeneous for a finite binary language. Israel J. Math. 49, 155–180 (1984). https://doi.org/10.1007/BF02760648
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DOI: https://doi.org/10.1007/BF02760648