  This paper is concerned with the Minkowski convolution of viscosity solutions
of fully nonlinear parabolic equations. We adopt this convolution to compare
viscosity solutions of initial-boundary value problems in different domains. As
a consequence, we can for instance obtain parabolic power concavity of
solutions to a general class of parabolic equations. Our results apply to the
Pucci operator, the normalized $q$-Laplacians with $1<q\leq\infty$, the Finsler
Laplacian and more general quasilinear operators.
