On Wed, Jul 24 2013, Willie WY Wong wrote: > Speaking as a mathematician (and A. Gottlieb will agree with me), I > would be rather annoyed that they chose (if this is not a misquote > from the original proposed documentation) to use '/' for set > difference instead of '\' as it is supposed to be.
I was also surprised to see `/'. A part of me was going to send about quotient groups (the normal usage of '/') but I managed to refrain myself. However, now that willie has opened the door ... / is normally used for quotients. For example, if we take the group Z of integers under addition and the subgroup 2Z of the even integers, then Z / 2Z is the quotient that results from taking Z and identifying all the elements of 2Z. So in Z / 2Z, all the even integers are zero and hence all odd integers are equivalent (since they differ by even integers, which are zero). Thus the quotient has only 2 elements and is the familiar group Z2, the integers mod 2. The above can be generalized. allan
