Algebraic theory of linear viscoelastic nematodynamics Part 1: Algebra   of nematic operators
  This first part of the paper develops algebraic theory of linear anisotropic, six-parametric nematic "N-operators" build up on the additive group of traceless second rank 3D tensors. These operators have been implicitly used in continual theories of nematic liquid crystals and weakly elastic nematic elastomers. It is shown that there exists a noncommutative, multiplicative group N6 of N-operators build up on a manifold in 6D space of parameters. Positive N-operators, which in physical applications holds thermodynamic stability constraints, form a subgroup of group N6 on a more complicated manifold in parametric space. A three-parametric, commutative transversal-isotropic subgroup S3 < N6 of positive symmetric nematic operators is also briefly discussed. The special case of singular, non-negative symmetric N-operators reveals the algebraic structure of nematic soft deformation modes. 
Arkady I. Leonov