Formalizing complex plane geometry


DOI: 10.1007/s10472-014-9436-4

Cite this article as:
Marić, F. & Petrović, D. Ann Math Artif Intell (2015) 74: 271. doi:10.1007/s10472-014-9436-4


Deep connections between complex numbers and geometry had been well known and carefully studied centuries ago. Fundamental objects that are investigated are the complex plane (usually extended by a single infinite point), its objects (points, lines and circles), and groups of transformations that act on them (e.g., inversions and Möbius transformations). In this paper, we treat the geometry of complex numbers formally and present a fully mechanically verified development within the theorem prover Isabelle/HOL. Apart from applications in formalizing mathematics and in education, this work serves as a ground for formally investigating various non-Euclidean geometries and their intimate connections. We discuss different approaches to formalization and discuss the major advantages of the more algebraically oriented approach.


Interactive theorem proving Complex plane geometry Möbius transformations 

Mathematics Subject Classifications (2010)

68T15 51B10 97I80 

Copyright information

© Springer International Publishing Switzerland 2014

Authors and Affiliations

  1. 1.Faculty of MathematicsUniversity of BelgradeBelgradeSerbia

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