On the prolongation structures of Petrov type III vacuum spacetime equations
arXiv:0910.3478
Abstract
The universal covering symmetry algebra of the Robinson-Trautman equations of Petrov Type III is shown to include the infinite-dimensional affine Kac-Moody algebra A_1 as a prolongation algebra. This algebra has slower growth than the contragradient algebra K_2 obtained previously for this equation.
arXiv commentProblems with the classification of the infinite-dimensional algebra