Infinite-Dimensional Prolongation Structures for the Robinson–Trautman Type III Metric

The universal covering symmetry algebra of the Robinson–Trautman equations of Petrov Type III is shown to include the infinite-dimensional Lie algebra A2⊕C[λ−1, λ], the loop algebra over A2. This algebra has slower growth than the contragradient algebra K2 obtained previously for this metric by other authors.