Frigyes Riesz between the two World Wars

Frigyes Riesz (22 January 1880 to 28 February 1956), was a Hungarian mathematician today best known for his work on functional analysis. His biography contains reference only to a few events of his life. The present paper intends to contribute to a critical revision of Riesz's biography focusing on three highly politicized moments of his life by using historical sources that have not been studied yet. The focus lies on the following moments: at the end of the First World War, Riesz described in a letter the tense situation in Koloszvár before the exile of the whole university. In the 1920s, he founded in Szeged a new mathematical journal and wrote to colleagues asking for support. During the Second World War, his Jewish ancestry determined the fate of his relatives and of himself, and caused his colleagues abroad to become worried about him.