  We introduce the M-representation of polytopes, which makes it possible to
compute linear transformations, convex hulls, and Minkowski sums with linear
complexity in the dimension of the polytopes. When the polytope is a convex
hull of a zonotope and a polytope, the representation size can be smaller than
any of the known representations (V-representation, H-representation, and
Z-representation). We also provide a variant of the M-representation: The chain
representation is more compact and we can directly use it to compute linear
transformations and convex hulls -- for all other operations on the chain
representation, one requires a conversion to the M-representation.
