Presenting degenerate Ringel–Hall algebras of cyclic quivers

Using the generators labelled by simple and sincere semisimple modules for the Ringel–Hall algebra Hq(n) of a cyclic quiver Δ(n), we give a presentation for the degenerate algebra H0(n). This is achieved by establishing a presentation for the generic extension monoid algebra of Δ(n). As an application, we show that both the degenerate Ringel–Hall algebra and the degenerate quantum affine sln admit multiplicative bases.