A Synthetic Proof of Pappus’ Theorem in Tarski’s Geometry

Journal of Automated Reasoning - Tập 58 - Trang 209-230 - 2016
Gabriel Braun1, Julien Narboux1
1ICube, UMR 7357, University of Strasbourg - CNRS, Strasbourg, France

Tóm tắt

In this paper, we report on the formalization of a synthetic proof of Pappus’ theorem. We provide two versions of the theorem: the first one is proved in neutral geometry (without assuming the parallel postulate), the second (usual) version is proved in Euclidean geometry. The proof that we formalize is the one presented by Hilbert in The Foundations of Geometry, which has been described in detail by Schwabhäuser, Szmielew and Tarski in part I of Metamathematische Methoden in der Geometrie. We highlight the steps that are still missing in this later version. The proofs are checked formally using the Coq proof assistant. Our proofs are based on Tarski’s axiom system for geometry without any continuity axiom. This theorem is an important milestone toward obtaining the arithmetization of geometry, which will allow us to provide a connection between analytic and synthetic geometry.

Tài liệu tham khảo

Behnke, H., Gould, S.H.: Fundamentals of Mathematics: Geometry. MIT Press, New York (1974)

Boutry, P., Narboux, J., Schreck, P.: Parallel Postulates and Decidability of Intersection of Lines: A Mechanized Study Within Tarski’s System of Geometry. Submitted, July (2015)

Boutry, P., Narboux, J., Schreck, P., Braun, G.: Ashort note about case distinctions in Tarski’s geometry. In: Botana, F., Quaresma, P. (eds.) Automated Deduction in Geometry 2014, Proceedings of ADG 2014, pp. 1–15. Coimbra, Portugal (2014)

Boutry, P., Narboux, J., Schreck, P., Braun, G.: Using small scale automation to improve both accessibility andreadability of formal proofs in geometry. In: Botana, F., Quaresma, P. (eds.) Automated Deduction in Geometry2014, Proceedings of ADG 2014, pp. 1–19. Coimbra, Portugal (2014)

Castéran, P.: Coq + \(\epsilon \)? In: JFLA, pp. 1–15 (2007)

Hilbert, D.: Foundations of Geometry (Grundlagen der Geometrie). Open Court, La Salle, Illinois, 1960. Second English edition, translated from the tenth German edition by Leo Unger. Original publication date (1899)

Janicic, P., Narboux, J., Quaresma, P.: The area method: a recapitulation. J. Autom. Reason. 48(4), 489–532 (2012)