A Groupoid over for which and are differentiable manifolds and , , and multiplication are differentiable maps. Furthermore, the derivatives of and are required to have maximal Rank everywhere. Here, and are maps from onto with and
See also Lie Algebroid, Nilpotent Lie Group, Semisimple Lie Group, Solvable Lie Group
Weinstein, A. ``Groupoids: Unifying Internal and External Symmetry.'' Not. Amer. Math. Soc. 43, 744-752, 1996.