Strict polynomial functors and multisets
  We prove a generalisation to any characteristic of a result of Macdonald that describes strict polynomial functors in characteristic zero in terms of representations of the groupoid of finite sets and bijections. Our result will give an analogous description in terms of finite multisets and an extension of the notion of bijection appropriate for multisets. A projected application is to the description of strict polynomial monads that will give a notion generalising (linear algebra) operads. 
Torsten Ekedahl and Pelle Salomonsson