Continuity of the operation in a semilattice
Tom 21 / 1970
                    
                    
                        Colloquium Mathematicum 21 (1970), 49-52                    
                                        
                        DOI: 10.4064/cm-21-1-49-52                    
                                    
                                                                
                             
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            