Paolo Pizzetti: The forgotten originator of triangle comparison geometry

Victor Pambuccian, Tudor Zamfirescu

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The theorem comparing the angles of two geodesic triangles with the same side lengths lying on surfaces with different curvatures, commonly attributed for the two-dimensional case to A.D. Alexandrov (1948) and for the n-dimensional Riemannian case to V.A. Toponogov (1959), goes back, for the two-dimensional case, to Paolo Pizzetti (1907b). Besides suggesting a correction of the historical narrative regarding the development of comparison geometry, the present note also mentions possible reasons for the oversight.

Original languageEnglish (US)
Pages (from-to)415-422
Number of pages8
JournalHistoria Mathematica
Issue number3
StatePublished - Aug 2011


  • A.D. Alexandrov
  • Comparison geometry
  • Paolo Pizzetti
  • V.A. Toponogov

ASJC Scopus subject areas

  • Mathematics(all)
  • History


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