Affineness and affinization of the Eilenberg–Mac Lane stack of the unipotent completion
For an integer nnn, let \bbH\bbH\bbH be the affine group scheme of formal series P(X)∈1+XA[[X]]P(X)\in 1+XA[[X]]P(X)∈1+XA[[X]] satisfying P(X)P(Y)=P(X+Y+XY)P(X)P(Y)=P(X+Y+XY)P(X)P(Y)=P(X+Y+XY). The assignment m↦(1+X)mm\mapsto(1+X)^mm↦(1+X)m defines a morphism…
MathDB