# Documentation

a rectangular band is a nowhere commutative semigroup. That is to say, if ab = ba then a = b. From this it follows classically that aa = a and that such a band is isomorphic to the following structure

Rect i j |

a rectangular band is a nowhere commutative semigroup. That is to say, if ab = ba then a = b. From this it follows classically that aa = a and that such a band is isomorphic to the following structure

Rect i j |