Carl Johann Adolf Alexander Witting (18 December 1861 – 29 November 1946) was a German mathematician. Family Witting was born in Dresden as the first child of the musician Carl Witting (1823–1907) and the painter Minna Witting, née Japha (1828–1882). Alexander Witting married the pianist Sophie Sebass (1864–1924) in 1889. They had two daughters and a son: Tillyta (1890–1970), Lotte (1894–1971) and the physicist Rudolf Witting (1899–1963). In view of the artistically affected family environment – father musician, mother painter, aunt Louise Japha (1826–1910) pianist, sister Agnes Witting (1863–1937) singer, brother Walther Witting painter – it does not surprise that Alexander Witting also painted sometimes and regularly made music, even beyond the narrow circle of family or colleagues. Education He successfully completed his final grammar school examinations at the Städtische Gymnasium zum Heiligen Kreuz (Kreuzschule) in Dresden at Easter 1880, served his military service for one year and commenced the study at the teachers department of the Polytechnikum Dresden at the summer term 1881. In spring 1885 he successfully completed the examinations for teachers at secondary schools, authorizing him for mathematics and physics in all classes of grammar schools and junior highs, as well as for geography excluding the preparations of the final secondary school examinations. A travel grant of the Polytechnikum allowed him to earn a doctorate, possible in those days at universities only. On 1 April 1885 Witting commenced his probationary year as teacher at the Thomasschule in Leipzig, and at the same time he attended courses and seminars at the university of Leipzig, esp. under Felix Klein, from whom he also received the topic for his dissertation. On 4 August 1886 he was accredited with a PhD at the Georg-August-Universität in Göttingen, the new work-place of Felix Klein. Career as a teacher From 1 December 1886 he worked as permanent teacher at the Städtische Gymnasium zum Heiligen Kreuz (Kreuzschule) by the will of the council of city Dresden. There Witting taught until his retirement as schoolmaster, lecturer, senior teacher, and professor. Extra officially he assisted for a long time at the chair for descriptive geometry of the TH Dresden, and he designed advertising brochures for the renowned concern Koch & Stenzel at Dresden. Alexander Witting was one of those secondary-school teachers, who remained being associated with the development of their science, and who published frequently themselves. As teacher of a grammar school with close contacts to both,