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 \(H = kG^*,\) then our construction recovers the work of M. Dokuchaev and N. Zhukavets. We also study the partial modules and comodules of the non-commutative non-cocommutative Kac-Paljutkin algebra \(\mathcal{A}\).