I like the notation of Gauss of three parallel horizontal lines between the
numbers a and b to state that a is congruent to b (mod c) to mean that c
measures the difference between a and b (or leaves the same remainder when
it measures both a and b), but I am not so sure that I like the word
*congruence*. Since it is so well established, I certainly do not want to
change it, but I am not sure why it was chosen in the first place. The
word seems to fit so much better figures that are superimposable. No?
Best wishes from Annapolis,
Sam Kutler