Normal Hopf algebras in cocycle deformations of finite groups

CÉSAR GALINDO Y SONIA NATALE

MANUSCRIPTA MATHEMATICA

Springer Verlag

Lugar: Dordrecht; Año: 2008 vol. 125 p. 501 - 514

0025-2611

Let G be a finite group and let p: G --> G´ be a surjective group homomorphism. Consider the cocycle deformation L = H^{sigma} of the Hopf algebra H = k^G of k-valued linear functions on G, with respect to some convolution invertible 2-cocycle sigma. The (normal) Hopf subalgebra k^G´ of  k^G corresponds to a Hopf subalgebra L´ of L. Our main result is an explicit necessary and sufficient condition, in group-theoretical terms, for the normality of L´ in L.