I would like to create a rank 4 symbolic tensor with this symmetries
(1) C_ijkl = C_jikl
(2) C_ijkl = C_ijlk
(3) C_ijkl = C_klij
is there any way to apply symmetry (3)?
symmetry (1) and (2) can be applied as:
cAr = SymmetrizedArray[pos_ -> c[pos], {3, 3, 3, 3}, {Symmetric[{1, 2}],
Symmetric[{3, 4}]}]; cAr // MatrixForm