TURING, Alan Mathison (1912-1954). 'Finite approximations to lie groups.' Offprint from: Annals of Mathematics, vol. 39, no. 1. Princeton, NJ: 1938. 8° (255 x 175mm). 8pp., 105-111. Original wrappers, stapled (faint spotting and uneven fading to upper wrapper). Provenance: R.O. Gandy (occasional pencil marginalia). [Sold with:] -- 'The extensions of a group.' Offprint from: Compositio Mathematica, vol. 5, fascicle 3. Groningen: 1938. 8° (248 x 170mm). 12pp., 358-367. Original wrappers, with overlay printing of Turing's name and title to upper cover, stapled (faint sunning).

TURING ON GROUP THEORY. 'A new departure, which arose through contact with von Neumann. It was a problem suggested by the emigré Polish mathematician S. Ulam: that of asking whether continuous groups could be approximated by finite groups, rather like approximating a sphere by polyhedra. Von Neumann had passed the problem to Alan, who successfully dealt with it by April' (Hodges pp.129-130). Newman 1938a and 1938b.

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