Hello, Been a long time lurker, but first time poster. I hope I can be very thorough and descriptive. So, I have been battling with a double inner product of a 2nd order tensor with a 4th order one. So my question is: How do we expand (using tensor properties) a double dot product of the basis vectors to a simpler one? [tex](e_ie_je_ke_l):(e_me_n)=?[/tex] and [tex](e_ie_j):(e_ke_le_me_n)=?[/tex] Thanks a lot!!