An exact proof term for the current goal is CD_minus_mul_distrL {3} CSNo quaternion_tag_fresh minus_CSNo conj_CSNo add_CSNo mul_CSNo CSNo_minus_CSNo CSNo_conj_CSNo CSNo_add_CSNo CSNo_mul_CSNo minus_add_CSNo minus_mul_CSNo_distrR minus_mul_CSNo_distrL.