Johannes Hjelmslev

Johannes Trolle Hjelmslev (Danish: [ˈjɛlˀmsleʊ]) (7 April 1873 – 16 February 1950) was a mathematician from Hørning, Denmark. Hjelmslev worked in geometry and history of geometry. He was the discoverer and eponym of the Hjelmslev transformation, a method for mapping an entire hyperbolic plane into a circle with a finite radius. He was the father of Louis Hjelmslev.