Margherita Beloch Piazzolla

Margherita Piazzola Beloch (; 12 July 1879 – 28 September 1976) was an Italian mathematician who worked in algebraic geometry, algebraic topology and photogrammetry.

Biography Beloch, born in Frascati, was the daughter of the German historian Karl Julius Beloch, who taught ancient history for 50 years at Sapienza University of Rome, and American Bella Bailey (daughter of Gamaliel Bailey).

Castelnuovo was very impressed with her talent and offered her the position of assistant which Beloch took and held until 1919, when she moved to Pavia. In 1920 she moved to Palermo to work under Michele De Franchis, an important figure of the Italian school of algebraic geometry at the time. "Hyperelliptic surfaces of rank 2 are characterised by having 16 rational curves."

Beloch also made contributions to the theory of skew algebraic curves. She continued working on topological properties of algebraic curves either planar or lying on ruled or cubic surfaces for most of her life, writing about a dozen papers on these subjects.

Around 1940 Beloch become more and more interested in photogrammetry and the application of mathematics, and in particular algebraic geometry, to it. She is also known for her contribution to the mathematics of paper folding: In particular she seems to have been the first to formalise an origami move which allows, when possible, to construct by paper folding the common tangents to two parabolas. As a consequence she showed how to extract cubic roots by paper folding, something that is impossible to do by ruler and compass. The move she used has been called the Beloch fold.