Abstract
In this paper we investigate the abstract angle measure for affine metric spaces. Common features and differences between orthogonal angles and angles with measure ≠ 0 are examined. It turns out that an affine collineation which maps angles with a certain fixed measure α ≠ 0,4 to angles with another fixed measure β is already a metric collineation in nearly all cases (fundamental theorem). An analogous result is stated for projective metric spaces. Some applications concerning minimal conditions for metric collineations are given.
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Alpers, B.: Zum Transitivitätsverhalten metrischer Kollineationsgruppen, Geom.Ded. 30(1989), 305–324.
Alpers, B.: Eine Note zur Charakterisierung von Ähnlichkeitsabbildungen, J.Geom. 35(1989), 1–6.
Benz, W. und Schröder, E.M.: Bestimmung der orthogonalitätstreuen Permutationen euklidischer Räume, Geom.Ded. 21(1986), 265–276.
Brauner, H.: Geometrie projektiver Räume 1,11, BL, Mannheim 1976.
Lester, J.A.: Martin’s theorem for euclidean n-space and a generalization to the perimeter case, J.Geom. 27(1986), 29–35.
-: Distance-preserving transformations, in: Handbook of Geometry (ed. F. Buekenhout), North Holland, to appear.
Scharlau, W.: Quadratic and hermitian forms, Springer, Berlin et al. 1985.
Schröder, E.M.: Zur Kennzeichnung distanztreuer Abbildungen in nichteuklidischen Räumen, J.Geom. 15(1980), 108–118.
Schröder, E.M.: Fundamentalsätze der metrischen Geometrie, J.Geom. 27(1986), 36–59.
-: Metric geometry, in: Handbook of Geometry (ed. F.Buekenhout), North Holland, to appear.
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This article was written during the author’s stay as a postdoctoral fellow at the University of Saskatchewan in Saskatoon. The author would like to thank this institution, in particular Prof. Marshall, for the hospitality and the inspiring atmosphere.
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Alpers, B. On Angles and The Fundamental Theorems of Metric Geometry. Results. Math. 17, 15–26 (1990). https://doi.org/10.1007/BF03322626
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DOI: https://doi.org/10.1007/BF03322626