57. Антон Шафаревич Polytopal linear groups

Let P Rn be a lattice polytope; i. e., P is a convex hull of a finite subset of Zn Rn. Consider the subsemigroup SP in Zn+1 generated by the set (x; 1), x PZn. The polytopal algebra associated with P is the semigroup algebra kSP where k is a field. The algebra kSP is naturally graded by the group Z. Following the work of Winfried Bruns and Joseph Gubeladze we will give a description of the group of graded automorphisms of kSP. References: 1 Winfried Bruns and Joseph Gubeladze. Polytopal linear groups. Journal of Algebra 218, 715737 (1999)