PROBs and perverse sheaves II. Ran spaces and 0-cycles with coefficients

Abstract

We consider the space Z(C,L) of 0-cycles on the complex line C with coefficients in a commutative monoid L subject to certain conditions. Such spaces include the symmetric products (for L=Z_+) and the Ran space (for L=T={ True, False} being the Boolean algebra of truth values). We describe the appropriately defined category of perverse sheaves on Z(C,L) in terms of the braided category (PROB) generated by the components of the universal $L$-graded bialgebra. We give another description in terms of so-called Janus sheaves which are objects of mixed functoriality (data covariant in one direction and contravariant in the other) on a category formed by certain matrices with entries in L. The matrices in question are analogs of contingency tables familiar in statistics.