In category theory, a branch of mathematics, a pulation square (also called a Doolittle diagram) is a diagram that is simultaneously a pullback square and a pushout square. It is a self-dual concept.
Famous quotes containing the word square:
“The square dance fiddler’s first concern is to carry a tune, but he must carry it loud enough to be heard over the noise of stamping feet, the cries of the “caller,” and the shouts of the dancers. When he fiddles, he “fiddles all over”; feet, hands, knees, head, and eyes are all busy.”
—State of Oklahoma, U.S. public relief program (1935-1943)