A Modern View of Geometry [Blumenthal]
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A Modern View of Geometry
Book name:A Modern View of Geometry
Author: Leonard M. Blumenthal
Publication date: April 19, 2017 — Dover reissue; originally published in 1961, with the first Dover edition appearing in 1980
Publisher: Dover Publications
ISBN: 978-0-486-82113-9
Length: 208 pages 

Summary 

Leonard M. Blumenthal’s A Modern View of Geometry presents geometry not primarily as a collection of constructions and formulas, but as an axiomatic mathematical structure. Beginning with the historical development of Euclidean geometry—especially the problems surrounding Euclid's fifth, or parallel, postulate—the book explains how the discovery of non-Euclidean geometries transformed mathematicians' understanding of what a geometry actually is. Blumenthal introduces the logical tools needed for this viewpoint, including elementary set theory, propositional logic, axioms, independence, consistency, and mathematical models. 

A major part of the book studies affine and projective geometry through coordinate systems. Blumenthal shows how geometric structures can be associated with algebraic ones, particularly through planar ternary rings and coordinate fields. The Desargues and Pappus configurations play an important role: imposing these geometric properties progressively strengthens the underlying algebraic structure until familiar analytic geometry over a field emerges. The treatment then moves to projective planes, the principle of duality, finite projective planes, Desarguesian and Pappian planes, illustrating the deep relationship between geometry and algebra

The final portion returns to metric geometry and asks what additional axioms are required to recover concepts such as distance, angle, congruence, and perpendicularity. Blumenthal develops axiomatic descriptions of the Euclidean plane and then considers non-Euclidean geometries, including two-dimensional spherical geometry. The overall message is that Euclidean, affine, projective, and non-Euclidean geometries can all be understood as different mathematical systems generated by different choices of axioms. The book is therefore particularly suitable for advanced undergraduates, graduate students, and readers interested in the foundations of geometry, rather than those looking mainly for classical Euclidean problem solving. 

Key takeaways
  • Geometry is fundamentally axiomatic: changing one or more axioms can produce entirely different but internally consistent geometries.
  • Algebra and geometry are closely connected: coordinate systems translate geometric incidence properties into algebraic operations.
  • Desargues' and Pappus' theorems are structural, not merely classical geometry results; they determine important properties of the algebra associated with a plane.
  • The book provides a bridge from classical Euclid to affine, projective, Euclidean, and non-Euclidean geometry, emphasizing the common logical framework behind them. 

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