Central idempotents of the bifree and left-free double Burnside ring

Robert Boltje, Burkhard Külshammer

We determine the blocks, i.e., the primitive central idempotents, of the bifree double Burnside ring $B^{\Delta }(G,G)$ and the left-free double Burnside ring $B^{\trl}(G,G)$, as well as t…