Introducing Crystalline Graded Algebras
  We introduce a new class of graded rings extending the class of generalized Weyl algebras. These rings are orders in crossed products of the most general type, and we introduce their basic structure theory. We provide an extensive list of examples, some completely new but also some considered earlier, and highlight some specific structure results. Many new and interesting problems about the crystalline graded rings may be identified. 
Erna Nauwelaerts and Freddy Van Oystaeyen