Constructing non-compact operators into $c_0$
Tom 201 / 2010
                    
                    
                        Studia Mathematica 201 (2010), 65-67                    
                                        
                        MSC: 47B07, 46B15.                    
                                        
                        DOI: 10.4064/sm201-1-5                    
                                    
                                                Streszczenie
We prove that for each dense non-compact linear operator $S:X\to Y$ between Banach spaces there is a linear operator $T:Y\to c_0$ such that the operator $TS:X\to c_0$ is not compact. This generalizes the Josefson–Nissenzweig Theorem.
 
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            