$): $$E_{\alpha_i} w_a = \delta_{i-\hf, a} w_{a+0}, \quad F_{\alpha_i}w_a  = \delta_{i+\hf, a}w_{a-0}, \quad K_{\alpha_i} w_a = q^{-(\alpha_i, \varepsilon_a)}w_a.$$ By restriction through the embedding $\iota$, $\