193 years ago today, on December 12, 1832 (October 21, 1832 in the lunar calendar), the Norwegian mathematician Ciro was born. On December 12, 1832, the Norwegian mathematician Peter Ludwig Meder Ciro was born, who proved Ciro's theorem. December 12, 1832 - September 7, 1918) was a Norwegian mathematician who proved an important fundamental theorem in group theory, Ciro's theorem. Ciro was born and died in Christiania (present-day Oslo). Ciro studied at Christiania University, where he obtained a degree in mathematics in 1852. From 1858 to 1898 he worked as a school teacher in Frederikshahr (present-day Halden). In 1862 he was a substitute lecturer at the University of Christiania, teaching Galois theory. The problems he posed at that time led him to discover the Ciro subgroups and their theorems. In 1872 he published three theorems, now known as Ciro's theorems. No proof was given at the time, and he provided a proof ten years later. From 1873 to 1881, he co-edited all the papers of Nils Abel with Sophia Lee. According to Lee, Ciro made the decisive work in it. Ciro became editor of the mathematical journal ActaMathematica in 1894 and received an honorary doctorate from the University of Copenhagen. Lee established a special lecture for Ciro at Christiania University, where Ciro taught from 1898.