Towards a classification of simple partial comodules of Hopf algebras

Abstract

Making the first steps towards a classification of simple partial comodules, we give a general construction for partial comodules of a Hopf algebra H using central idempotents in right coideal subalgebras and show that any 1-dimensional partial comodule is of that form. We conjecture that in fact all finite-dimensional simple partial H-comodules arise this way. For $H=kG$ for some finite group G, we give conditions for the constructed partial comodule to be simple, and we determine when two of them are isomorphic. If $H=k{G}^{⁎}$, then our construction recovers the work of M. Dokuchaev and N. Zhukavets [12]. We also study the partial modules and comodules of the non-commutative non-cocommutative Kac-Paljutkin algebra $A$.