Coideal subalgebras of quantum $SL_2$ at roots of unity (2410.10064v2)

Abstract: We classify right coideal subalgebras of the finite-dimensional quotient of the quantized enveloping algebra $U_q(\mathfrak{sl}_2)$ and that of the quantized coordinate algebra $\mathcal{O}_q(SL_2)$ at a root of unity $q$ of odd order. All those coideal subalgebras are described by generators and relations.