Remarks on Convexity in Dimension $(2,2)$
Tom 56 / 2008
                    
                    
                        Bulletin Polish Acad. Sci. Math. 56 (2008), 207-211                    
                                        
                        MSC: 26B25, 52A41.                    
                                        
                        DOI: 10.4064/ba56-3-3                    
                                    
                                                Streszczenie
We consider different convexity notions for functions $F\colon\mathbb R^{2\times 2}\to\mathbb R$. We give a new characterisation of polyconvexity and a sufficient condition for quasiconvexity.
 
             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                             
                                                         
                                                            