Firstorder_plugin.Unify
exception UFAIL of EConstr.constr * EConstr.constr
val unif_atoms : Environ.env -> Evd.evar_map -> Constr.metavariable -> EConstr.constr -> Formula.atom -> Formula.atom -> instance option
val more_general : Environ.env -> Evd.evar_map -> (int * EConstr.constr) -> (int * EConstr.constr) -> bool