An exact proof term for the current goal is CD_conj_mul {2} SNo complex_tag_fresh minus_SNo conj add_SNo mul_SNo SNo_minus_SNo (λz H ⇒ H) SNo_add_SNo SNo_mul_SNo minus_SNo_invol (λx _ q H ⇒ H) (λx _ q H ⇒ H) (λx y _ _ q H ⇒ H) minus_add_SNo_distr add_SNo_com mul_SNo_com mul_SNo_minus_distrR mul_SNo_minus_distrL.