Chern-Simons gravity, based on a non-semisimple group
  The gauge theory-formulation of string-motivated lineal gravity proposed by Cangemi and Jackiw is obtained by dimensional reduction from $(2+1)$ dimensional gravity with a Chern-Simons Lagrangian. 
C. Duval, Z. Horv\'ath, P. A. Horv\'athy