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Topological properties of real number representations. (English) Zbl 1039.03036

Summary: We prove three results about representations of real numbers (or elements of other topological spaces) by infinite strings. Such representations are useful for the description of real number computations performed by digital computers or by Turing machines. First, we show that the so-called admissible representations, a topologically natural class of representations introduced by Kreitz and Weihrauch, are essentially the continuous extensions (with a well-behaved domain) of continuous and open representations. Second, we show that there is no admissible representation of the real numbers such that every real number has only finitely many names. Third, we show that a rather interesting property of admissible real number representations holds true also for a certain non-admissible representation, namely for the naive Cauchy representation: the property that continuity is equivalent to relative continuity with respect to the representation.

MSC:

03D60 Computability and recursion theory on ordinals, admissible sets, etc.
03F60 Constructive and recursive analysis
Full Text: DOI

References:

[1] T. Deil, Darstellungen und Berechenbarkeit reeller Zahlen, Informatik Berichte 51, FernUniversität Hagen, Hagen, December 1984, Dissertation.; T. Deil, Darstellungen und Berechenbarkeit reeller Zahlen, Informatik Berichte 51, FernUniversität Hagen, Hagen, December 1984, Dissertation.
[2] Engelking, R., General Topology. General Topology, Sigma Series in Pure Mathematics, Vol. 6 (1989), Heldermann: Heldermann Berlin · Zbl 0684.54001
[3] Hauck, J., Zur Präzisierung des Begriffes berechenbare reelle Funktion, Z. Math. Logik Grundlag. Math., 17, 295-300 (1971) · Zbl 0231.02043
[4] Hauck, J., Berechenbare reelle Funktionen, Z. Math. Logik Grundlag. Math., 19, 121-140 (1973) · Zbl 0298.02028
[5] Hauck, J., Konstruktive Darstellungen in topologischen Räumen mit rekursiver Basis, Z. Math. Logik Grundlag. Math., 26, 565-576 (1980) · Zbl 0455.03025
[6] Hertling, P., A real number structure that is effectively categorical, Math. Logic Q., 45, 2, 147-182 (1999) · Zbl 0946.03050
[7] Kreitz, C.; Weihrauch, K., Theory of representations, Theoret. Comput. Sci., 38, 35-53 (1985) · Zbl 0588.03031
[8] M. Schröder, Topological spaces allowing type 2 complexity theory, in: Ker-I Ko K. Weihrauch (Eds.), Computability and Complexity in Analysis, Informatik Berichte, Vol. 190, pp. 41-53, FernUniversität Hagen, September 1995, CCA Workshop, Hagen, August 19-20, 1995.; M. Schröder, Topological spaces allowing type 2 complexity theory, in: Ker-I Ko K. Weihrauch (Eds.), Computability and Complexity in Analysis, Informatik Berichte, Vol. 190, pp. 41-53, FernUniversität Hagen, September 1995, CCA Workshop, Hagen, August 19-20, 1995.
[9] M. Schröder, Welche topologischen Räume erlauben Typ2-Komplexitätstheorie?, Informatik Berichte 178, FernUniversität Hagen, Hagen, May 1995.; M. Schröder, Welche topologischen Räume erlauben Typ2-Komplexitätstheorie?, Informatik Berichte 178, FernUniversität Hagen, Hagen, May 1995.
[10] Weihrauch, K., Computability. Computability, EATCS Monographs on Theoretical Computer Science, Vol. 9 (1987), Springer: Springer Berlin · Zbl 0611.03002
[11] Weihrauch, K., Computable Analysis (2000), Springer: Springer Berlin · Zbl 0956.68056
[12] Weihrauch, K.; Kreitz, C., Representations of the real numbers and of the open subsets of the set of real numbers, Ann. Pure Appl. Logic, 35, 247-260 (1987) · Zbl 0643.03041
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