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MEASURING DEPENDENCE IN METRIC ABSTRACT ELEMENTARY CLASSES WITH PERTURBATIONS

Published online by Cambridge University Press:  09 January 2018

ÅSA HIRVONEN
Affiliation:
DEPARTMENT OF MATHEMATICS AND STATISTICS UNIVERSITY OF HELSINKI P.O. BOX 68, 00014HELSINKI FINLANDE-mail:[email protected]
TAPANI HYTTINEN
Affiliation:
DEPARTMENT OF MATHEMATICS AND STATISTICS UNIVERSITY OF HELSINKI P.O. BOX 68, 00014HELSINKI FINLANDE-mail:[email protected]

Abstract

We define and study a metric independence notion in a homogeneous metric abstract elementary class with perturbations that is dp-superstable (superstable wrt. the perturbation topology), weakly simple and has complete type spaces and we give a new example of such a class based on B. Zilber’s approximations of Weyl algebras. We introduce a way to measure the dependence of a tuple a from a set B over another set A. We prove basic properties of the notion, e.g., that a is independent of B over A in the usual sense of homogeneous model theory if and only if the measure of dependence is < ε for all ε > 0. In well behaved situations, the measure corresponds to the distance to a free extension. As an example of our measure of dependence we show a connection between the measure and entropy in models from quantum mechanics in which the spectrum of the observable is discrete. As an application, we show that weak simplicity implies a very strong form of simplicity and study the question of when the dependence inside a set of all realisations of some type can be seen to arise from a pregeometry in cases when the type is not regular. In the end of the paper, we demonstrate our notions and results in one more example: a class built from the p-adic integers.

Type
Articles
Copyright
Copyright © The Association for Symbolic Logic 2017 

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References

REFERENCES

Berenstein, A. and Henson, C., Model theory of probability spaces with an automorphism, manuscript, arXiv math/0405360.Google Scholar
Ben Yaacov, I., On perturbations of continuous structures. Journal of Mathematical Logic, vol. 8 (2008), no. 2, pp. 225249.CrossRefGoogle Scholar
Ben Yaacov, I. and Berenstein, A., On perturbations of Hilbert spaces and probability albegras with a generic automorphism. Journal of Logic and Analysis, vol. 1 (2009), no. 7, pp. 118.Google Scholar
Ben Yaacov, I. and Usvyatsov, A., On d-finiteness in continuous structures. Fundamenta Mathematicae, vol. 194 (2007), pp. 6788.CrossRefGoogle Scholar
Ben Yaacov, I., Usvyatsow, A., and Zadka, M., Generic automorphism of a Hilbert space, preprint.Google Scholar
Fuchs, L., Infinite Abelian Groups, vol. I, Pure and Applied Mathematics, vol. 36, Academic Press, New York-London, 1970.Google Scholar
Hirvonen, Å. and Hyttinen, T., Metric abstract elementary classes with perturbations. Fundamenta Mathematicae, vol. 217 (2012), pp. 123170.CrossRefGoogle Scholar
Hirvonen, Å. and Hyttinen, T., On eigenvectors and the Feynman propagator, manuscript.Google Scholar
Hyttinen, T. and Kesälä, M., Superstability in simple finitary AECs. Fundamenta Mathematicae, vol. 195 (2007), no. 3, pp. 221268.Google Scholar
Hyttinen, T. and Kesälä, M., Lascar types and Lascar automorphisms in abstract elementary classes. Notre Dame Journal of Formal Logic, vol. 52 (2011), no. 1, pp. 3954.CrossRefGoogle Scholar
Hyttinen, T. and Lessmann, O., A rank for the class of elementary submodels of a superstable homogeneous model, this Journal, vol. 67 (2002), no. 4, pp. 1469–1482.Google Scholar
Hyttinen, T. and Shelah, S., Strong splitting in stable homogeneous models. Annals of Pure and Applied Logic, vol. 103 (2000), no. 1–3, pp. 201228.CrossRefGoogle Scholar
Iovino, J., Stable Banach spaces and Banach space structures, I and II, Models, Algebras, and Proofs (Bogotá, 1995) (Caicedo, X. and Montenegro, C. H., editors), Lecture Notes in Pure and Applied Mathematics, vol. 203, Dekker, New York, 1999, pp. 77117.Google Scholar
Kaplansky, I., Infinite Abelian Groups, University of Michigan Press, Ann Arbor, 1954.Google Scholar
Ochoa, M. A. and Villaveces, A., Sheaves of metric structures, Logic, Language, Information, and Computation (Väänänen, J., Hirvonen, Å., and de Queiroz, R., editors), Lecture Notes in Computer Science, vol. 9803, Springer, Berlin, 2016.Google Scholar
Petz, D., Entropy, von Neumann and the von Neumann entropy, John von Neumann and the Foundations of Quantum Physics (Budapest, 1999) (Rédei, M. and Stöltzner, M., editors), Vienna Circle Institute Yearbook, vol. 8, Kluwer Academic Publishers, Dordrecht, 2001, pp. 8396.CrossRefGoogle Scholar
Shelah, S., Classification Theory and the Number of Nonisomorphic models, second ed., Studies in Logic and the Foundations of Mathematics, vol. 92, North-Holland Publishing Co., Amsterdam, 1990.Google Scholar
Tribus, M. and McIrvine, E., Energy and information. Scientific American, vol. 225 (1971), no. 3, pp. 179188.Google Scholar
Zilber, B., The semantics of the canonical commutation relation, manuscript, arXiv:1604.07745.Google Scholar