Noncommutative Geometry and Topology in Prague

Jet Functors in Noncommutative Geometry

We construct an infinite family of endofunctors  on the category of left -modules, where  is a unital associative algebra over a commutative ring , equipped with an exterior algebra . We prove that these functors generalize the corresponding classical notion of jet functors. The functor  comes equipped with a natural transformation from the identity functor to itself, which plays the role of the classical prolongation map. This allows us to define the notion of linear differential operator with respect to . These retain most classical properties of differential operators, and operators such as partial derivatives and connections belong to this class. Moreover, we construct a functor of quantum symmetric forms  associated to , and proceed to introduce the corresponding noncommutative analogue of the Spencer -complex. We give necessary and sufficient conditions under which the jet functor  satisfies the jet exact sequence,   . This involves imposing mild homological conditions on the exterior algebra, in particular on the Spencer cohomology . This is a joint work with K. Flood and H. Winther.