groupoid,
n. 1. a set together with a binary operation under which it is closed. The positive real line with the binary operation given by
a * b = √(a2 + b)
produces a groupoid that is not a semi-group. 2. a category in which every arrow is invertible. In this sense a groupoid is like a group with multiplication only partially defined. See homotopy.
a * b = √(a2 + b)
produces a groupoid that is not a semi-group. 2. a category in which every arrow is invertible. In this sense a groupoid is like a group with multiplication only partially defined. See homotopy.