Elli Heesch, Heinrich Heesch and Hilbert’s eighteenth problem: collaborative research between philosophy, mathematics and application

This paper examines the hitherto unknown scientific collaboration between the siblings Elli Heesch (1904–1993) and Heinrich Heesch (1906–1995). Heinrich Heesch, a well-known mathematician, was spearheading the early development of the computer-aided proof of the four-colour theorem. Much less is known about his sister Elli Heesch, a philosopher and logician. Together with her brother she investigated tiling problems and worked out a solution of Hilbert’s 18th problem. In 1944, Elli and Heinrich Heesch wrote a joint treatise on the industrial application of the tessellation method, which was of great interest to the German war and armaments industry. The collaboration of the Heesch siblings illustrates individual, disciplinary, cultural, and political aspects of knowledge production. The common interplay of close family relations and socio-political conditions that we find here underlines the fact that women’s contributions to solving mathematical problems often remained invisible.