Template:Are You Sure/October 3
This Cayley graph shows the free group on two generators a and b.
• ... that mathematician Arthur Cayley (16 August 1821 – 26 January 1895) was the first to define the concept of a group in the modern way (as a set with a binary operation satisfying certain laws); and that formerly, when mathematicians spoke of "groups", they had meant permutation groups?
• ... that mathematician Reginald Robin Farquharson (3 October 1930 – 1 April 1973) worked on game theory because he was interested in both mathematics and politics; and that Farquharson's doctoral thesis, which analyzed voting systems, was influential when later published as Theory of Voting (Oxford: Blackwell, 1970)?
• ... that physicist and astrophyisicist Robert F. Christy was distraught at the outcome of the 1954 Oppenheimer security hearing; and that when Christy encountered Edward Teller, who had testified against Oppenheimer, at Los Alamos in 1954, Christy publicly refused to shake Teller's hand?