On bases in Banach spaces
Volume 170 / 2005
                    
                    
                        Studia Mathematica 170 (2005), 147-171                    
                                        
                        MSC: Primary 46B20; Secondary 03E75, 03E35.                    
                                        
                        DOI: 10.4064/sm170-2-3                    
                                    
                                                Abstract
We investigate various kinds of bases in infinite-dimensional Banach spaces. In particular, we consider the complexity of Hamel bases in separable and non-separable Banach spaces and show that in a separable Banach space a Hamel basis cannot be analytic, whereas there are non-separable Hilbert spaces which have a discrete and closed Hamel basis. Further we investigate the existence of certain complete minimal systems in $\ell _\infty $ as well as in separable Banach spaces.
 
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            