1972/06/01 by Roger C. Lyndon · 9 citations
Social Sciences · Mathematics · #Economic and Social Issues #Sharpening #Mathematics #Group (periodic table) #Extension (predicate logic) #Identity (music) #Pure mathematics #Combinatorics #Algebra over a field #Computer science #Physics #Aesthetics #Philosophy #Artificial intelligence #Quantum mechanics
paper · open access · doi:10.1112/jlms/s2-5.1.95
published in Journal of the London Mathematical Society s2-5(1), 95-101 (Wiley)
openalex publication_date 1972/06/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
The classical proof of the Dehn-Magmis Freiheitssatz, due to Magnus, is recast in the language of combinatorial geometry. This provides an extension of the Freiheitssatz from free groups to groups that are free products of groups isomorphic to subgroups of the additive group of real numbers, and at the same time, a sharpening of the author's Identity Theorem.