On Kato non-singularity
Volume 117 / 1996
                    
                    
                        Studia Mathematica 117 (1996), 107-114                    
                                        
                        DOI: 10.4064/sm-117-2-107-114                    
                                    
                                                Abstract
An exactness lemma offers a simplified account of the spectral properties of the "holomorphic" analogue of normal solvability.