Proceedings of the American Mathematical Society

Author(s): Fons van Engelen
Journal: Proc. Amer. Math. Soc. 124 (1996), 2589-2598.
MSC (1991): Primary 54H05, 54E35, 54F65; Secondary 03E15
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Abstract: We provide an example of a zero-dimensional (separable metric) absolute Borel set $X$

which is not homogeneous, but whose square $X \times X$ admits the structure of a topological group. We also construct a zero-dimensional absolute Borel set $Y$

such that

is a homogeneous non-group but $Y \times Y$ is a group. This answers questions of Arhangel'skii and Zhou.

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Retrieve articles in Proceedings of the American Mathematical Society with MSC (1991): 54H05, 54E35, 54F65, 03E15

Fons van Engelen
Affiliation: Erasmus Universiteit, Econometrisch Instituut, Postbus 1738, 3000~DR~~Rotterdam, The Netherlands
Email: engelen@wis.few.eur.nl

DOI: 10.1090/S0002-9939-96-03561-7
PII: S 0002-9939(96)03561-7
Keywords: Zero-dimensional, Borel, Wadge hierarchy, homogeneous
Received by editor(s): February 20, 1995
Communicated by: Franklin D. Tall
Copyright of article: Copyright 1996, American Mathematical Society

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