**Karl Peterson** was a Latvian mathematician worked in differential geometry and partial differential equations.

- Karl was born into a country which had been dominated by Russia since the end of the 18th century although Riga had been taken by the Russians long before.
- This caused unrest in the Latvian lands throughout much of Peterson's life.
- Karl attended the Gymnasium in Riga and he graduated in 1847 with excellent qualifications which meant that he as able to study at the University of Dorpat (now Tartu).
- Although a university had existed in Tartu since 1632, Peterson entered the Kaiserliche Universität zu Dorpat in Tartu (Dorpat) which had been established in 1802.
- At this University, Peterson studied under Ferdinand Minding.
- He was to have a strong influence on Peterson and give him the urge to undertake mathematical research.
- Peterson would follow in the footsteps of his professor in undertaking deep research while a school teacher, but unlike his professor he never became a university teacher.
- Peterson wrote an unpublished "candidate's" thesis, Über die Biegung der Flächen Ⓣ(On the bending of surfaces) (Dorpat, 1853) on differential geometry.
- The dissertation contains a derivation of two equations equivalent to those of Mainardi and Codazzi, and in it Peterson outlined a proof of the fundamental theorem of surface theory.
- After obtaining his candidate's degree, Peterson worked in Moscow as a teacher of mathematics.
- Largely because he was not at a university his results were not well known but they did influence Egorov in Moscow, but Peterson gained an international reputation only when Darboux and Bianchi used his results.
- Surfaces with such nets were first studied by Peterson in 1866.
- Peterson's paper 'On curves on surfaces' (1867) and the book 'Über Curven und Flächen' Ⓣ(On curves and surfaces) (1868) were devoted to differential geometry.
- Some of the results of these papers of Peterson were later duplicated by G Darboux and other foreign geometers, but after E Cosserat's translations of Peterson's main works from 1866-1867 were published in Toulouse in 1905, his work achieved general recognition.
- In addition to his mathematical research while he taught in Moscow schools, Peterson also worked with Brashman and Davidov in founding the Moscow Mathematical Society.
- The first such Society had been founded in 1810 but had ceased to function and a totally new Society, which Peterson helped found and organise, started to operate in 1864.
- Mathematicheskii Sbornik, the journal of the Society, first appeared in October 1866 and from that time on Peterson published almost all his research papers in that journal.

Born 25 May 1828, Riga, Russia (now Latvia). Died 19 April 1881, Moscow, Russia.

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Origin Latvia

**O’Connor, John J; Robertson, Edmund F**: MacTutor History of Mathematics Archive