A note on integral geometry in the inversive plane
Author: Jay P. Fillmore
Journal: Proc. Amer. Math. Soc. 78 (1980), 551-554
MSC: Primary 53C65; Secondary 60D05
MathSciNet review: 556631
Abstract: The density for circles in the Euclidean plane, which is invariant under the group of similitudes, is in fact invariant under the inversive group. The fundamental invariants of the inversive plane, angle and inversive distance, can be obtained from the measures of certain sets of circles.
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