Complex sentence: Simons theory with the gauge group SO (2,2) for a negative cosmological constant, and SO (3,1) for a positive one, which can be exactly solved, making this a toy model for quantum gravity.
Split into simpler sentences: Simons theory with the gauge group SO (2,2) for a negative cosmological constant, and SO (3,1) for a positive one. This theory can be exactly solved, making it a toy model for quantum gravity.