Abstract
The topological arithmetical hierarchy is the effective version of the Borel hierarchy. Its class Δta 2 is just large enough to include several types of pointsets in Euclidean spaces ℝk which are fundamental in computable analysis. As a crossbreed of Hausdorff's difference hierarchy in the Borel class ΔB 2 and Ershov's hierarchy in the class Δ0 2 of the arithmetical hierarchy, the Hausdorff-Ershov hierarchy introduced in this paper gives a powerful classification within Δta 2. This is based on suitable characterizations of the sets from Δta 2 which are obtained in a close analogy to those of the ΔB 2 sets as well as those of the Δ0 2 sets. A helpful tool in dealing with resolvable sets is contributed by the technique of depth analysis. On this basis, the hierarchy properties, in particular the strict inclusions between classes of different levels, can be shown by direct constructions of witness sets. The Hausdorff-Ershov hierarchy runs properly over all constructive ordinals, in contrast to Ershov's hierarchy whose denotation-independent version collapses at level ω 2. Also, some new characterizations of concepts of decidability for pointsets in Euclidean spaces are presented.
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References
Ash, C.J., Knight, J.F.: Recursive structures and Ershov's hierarchy. Mathematical Logic Quarterly 42, 461–468 (1996)
Epstein, R.L., Haas, R., Kramer, R.L.: Hierarchies of sets and degrees below 0'. In: Logic Year 1979/80, Univ. of Connecticut. M. Lerman, J.H. Schmerl, R.I. Soare, (eds.), LN in Math 859, Springer Verlag, pp. 32–48
Ershov, Yu.L.: A hierarchy of sets. I; II; III. Algebra i Logica, v. 7 (1968), no.1, 47-74; no.4, 15-47; v. 9 (1970), no.1, 34–51 (English translation by Plenum P.C.)
Hausdorff, F.: Grundzüge der Mengenlehre. W. de Gruyter & Co., Berlin and Leipzig 1914; Reprint: Chelsea P.C., New York 1949
Hausdorff, F.: Mengenlehre. W. de Gruyter & Co., Berlin and Leipzig, 1927
Hausdorff, F.: Gesammelte Werke, Band II: ``Grundzüge der Mengenlehre''. E. Brieskorn, S.D. Chatterji, M. Epple, U. Felgner, H. Herrlich, M. Hušek, V. Kanovej, P. Koepke, G. Preuß, W. Purkert und E. Scholz, (eds.), Springer Verlag, Berlin, Heidelberg, New York, 2002
Hemmerling, A.: On approximate and algebraic computability over the real numbers. Theoretical Computer Science 219, 185–223 (1999)
Hemmerling, A.: Effective metric spaces and representations of the reals. Theoretical Computer Science 284, 347–372 (2002)
Hemmerling, A.: Approximate decidability in Euclidean spaces. Mathematical Logic Quarterly 49, 34–56 (2003)
Hemmerling, A.: Characterizations of the class Δta 2 over Euclidean spaces. Mathematical Logic Quarterly 50, 507–519 (2004)
Hemmerling, A.: Hierarchies of function classes defined by the first-value operator. E.-M.-Arndt-Universität Greifswald, Preprint-Reihe Mathematik, Nr. 12/2004. (PS file available from: http://www.math-inf.uni-greifswald.de/preprints/titel04); Extended abstract in: Proc. of CCA'2004. Electronic Notes in Theoretical Computer Science 120, 59–72 (2005)
Hertling, P.: Unstetigkeitsgrade von Funktionen in der effektiven Analysis. Dissertation. Informatik Berichte 208-11/1996, Fern-Uni Hagen, 1996
Hertling, P., Weihrauch, K.: Levels of degeneracy and exact lower complexity bounds for geometric algorithms. Proc. of the 6th Canadian Conf. on Computational Geometry, Saskatoon, 1994. pp. 237–242
Kanovej, V., Koepke, P.: Deskriptive Mengenlehre in Hausdorffs Grundzügen der Mengenlehre. In: [6], pp. 773–787
Kechris, A.S.: Classical descriptive set theory. Springer Verlag, New York, 1995
Ko, K.-I.: Complexity theory of real functions. Birkhäuser, Boston et al., 1991
Ko, K.-I., Friedman, H.: Computational complexity of real functions. Theoretical Computer Science 20, 323–352 (1982)
Kreitz, C., Weihrauch, K.: Complexity theory on real numbers and functions. LN in Computer Science 145, 165–174 (1982)
Kuratowski, K.: Topology I. Academic Press, New York and London; PWN Warszawa, 1966
Moschovakis, Y.N.: Descriptive set theory. North-Holland P. C., Amsterdam et al., 1980
Odifreddi, P.: Classical recursion theory. North–Holland P.C., Amsterdam et al., 1989
Penrose, R.: The emperor's new mind. Oxford University Press, New York, 1989
Rogers, H. Jr.: Theory of recursive functions and effective computability. McGraw-Hill, New York, 1967
Selivanov, V.L.: Wadge degrees of ω-languages of deterministic Turing machines. Theoretical Informatics and Applications 37, 67–83 (2003)
Selivanov, V.L.: Difference hierarchy in ϕ-spaces. Preprint 2003, to appear in: Algebra and Logic
Wadge, W.W.: Reducibility and determinateness in the Baire space. Ph.D. Thesis. Univ. of California, Berkeley 1984
Weihrauch, K.: Computability on computable metric spaces. Theoretical Computer Science 113, 191–210 (1993)
Weihrauch, K.: Computable analysis. Springer–Verlag, Berlin et al., 2000
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Hemmerling, A. The Hausdorff-Ershov Hierarchy in Euclidean Spaces. Arch. Math. Logic 45, 323–350 (2006). https://doi.org/10.1007/s00153-005-0317-8
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DOI: https://doi.org/10.1007/s00153-005-0317-8
Key words or phrases
- Computable analysis
- Effective descriptive set theory
- Hausdorff's difference hierarchy
- Ershov's hierarchy
- Topological arithmetical hierarchy
- Resolvable sets
- Global and local depth of sets
- Recursivity in analysis
- Approximate decidability