About 90 "informal notes" by Kevin Brown on set theory and foundations: what is fuzzy logic, fractal logic, Cantor's diagonal proof, are all triangles isosceles, on Gauss's mountains, problems with the luminiferous...

In this applet, A and B are subsets of a universal set S. The list is given of the 16 different subsets of S that can be constructed from A and B using the basic set operations of union, intersection, and complement. The...