Maurits Joost Belinfante earned a PhD in maths in 1923 at the University of Amsterdam. He was a known checker player/composer.
The author Gerhard Durlacher met Belinfante in Theresiënstadt and wrote about him in his book Strepen aan de Hemel (Amsterdam 1985).
Addition of a visitor of the website
For additional information on Maurits Joost Belinfante, see:
D. van Dalen, L.E.J. Brouwer. Een Biografie (Amsterdam 2002)
D. van Dalen, Mystic, Geometr and Intuitionist, vol. 1 & 2 (Oxford University Press 1999, 2005)