We study generalised polynomial functors between presheaf categories, developing their mathematical theory together with computational applications. The main theoretical contribution is the introduction of discrete generalised polynomial functors, a class that lies in between the classes of cocontinuous and finitary functors, and is closed under composition, sums, finite products, and different...

Suppose G is a p-hyperelementary group and R is a commutative ring such that the order of G is a unit in R. Suppose J is either one of Quillen’s K-theory functors or one of Wall’s oriented L-theory functors. We show that J(RG) can be detected by applying J(R?) to the subquotients of G such that all normal abelian subgroups are cyclic. In 3.A.6 we show that such subquotients have a quite simple ...

Co)induction functors appear in several areas of Algebra in different forms. Interesting examples are the so called induction functors in the Theory of Affine Algebraic Groups. In this paper we investigate Hopf pairings (bialgebra pairings) and use them to study (co)induction functors for affine group schemes over arbitrary commutative ground rings. We present also a special type of Hopf pairin...

We consider two categories of C-algebras; in the first, the isomorphisms are ordinary isomorphisms, and in the second, the isomorphisms are Morita equivalences. We show how these two categories, and categories of dynamical systems based on them, crop up in a variety of C-algebraic contexts. We show that Rieffel’s construction of a fixed-point algebra for a proper action can be made into functor...

We generalize the work by Sobociński on relational presheaves and their connection with weak (bi)simulation for labelled transistion systems to a coalgebraic setting. We show that the coalgebraic notion of saturation studied in our previous work can be expressed in the language of lax functors in terms of existence of a certain adjunction between categories of lax functors. This observation all...

sl 3-Foams and the Khovanov-Lauda categorification of quantum sl k. Abstract In this paper I define certain interesting 2-functors from the Khovanov-Lauda 2-category which categorifies quantum sl k , for any k > 1, to a 2-category of universal sl 3 foams with corners. For want of a better name I use the term foamation to indicate those 2-functors. I conjecture the existence of similar 2-functor...

We describe structural properties of globally defined Mackey functors related to the stratification theory of algebras. We show that over a field of characteristic zero they form a highest weight category and we also determine precisely when this category is semisimple. This approach is used to show that the Cartan matrix is often symmetric and non-singular, and we are able to compute finite pa...

In this paper we study multidimensional persistence modules [5, 13] via what we call tame functors and noise systems. A noise system leads to a pseudo-metric topology on the category of tame functors. We show how this pseudo-metric can be used to identify persistent features of compact mul-tidimensional persistence modules. To count such features we introduce the feature counting invariant and ...

We use the connection between automata and logic to prove that a wide class of coalgebraic fixpoint logics enjoys uniform interpolation. To this aim, first we generalize one of the central results in coalgebraic automata theory, namely closure under projection, which is known to hold for weak-pullback preserving functors, to a more general class of functors, i.e.; functors with quasi-functorial...

Coequations, which are subsets of a cofree coalgebra, can be viewed as properties of systems. In case of a polynomial functor, a logic of coequations was formulated by J. Adámek. However, the logic is more complicated for other functors than polynomial ones, and simple deduction rules can no longer be formulated. A simpler coequational logic for finitely branching labelled transition systems wa...