Two-by-two upper triangular matrices and Morrey's conjecture

Terence L. J. Harris, Bernd Kirchheim, Chun-Chi Lin

It is shown that every homogeneous gradient Young measure supported on matrices of the form $\begin{pmatrix} a_{1,1} & \cdots & a_{1,n-1} & a_{1,n} \\ 0 & \cdots & 0 & a_{2,n} \end…