“…The order cancellation law or Rådström cancellation theorem [22,24], investigated also in [14,17,19], enables an embedding of a semigroup of convex sets into a quotient vector space called a Minkowski-Rådström-Hörmander space [11,27]. This space plays a crucial role in differentiation of nonsmooth functions (quasidifferential calculus of Demyanov and Rubinov [1,6,7,10,13,20]) and in integration and differentiation in the theory of multifunctions [4,5]. The cancellation by unbounded sets is especially challenging.…”