On the most general tensor B(sub ij) which is zero for i does not equal j, and the most general isotropic tensor I(sub ij)

摘要

It is shown that the most general second order tensor B sub ij which is zero for i not = j is proportional to the Kronecker delta (Delta sub ij). By a slight modification of that argument, the known result was obtained that the most general second order isotropic tensor is also proportional to Delta sub ij. These results are useful for instance in obtaining the stress tensor for a viscous fluid.