A relation between gravity in (3+1) dimensions and Pontrjagin topological invariant

M. Medina, J. A. Nieto
1996 Il Nuovo Cimento B Series 11  
A relation between the MacDowell-Mansouri theory of gravity and the Pontrjagin toplogical invariant in $(3+1)$ dimensions is discussed. This relation may be of especial interest in the quest of finding a mechanism to go from non-dynamical to dynamical gravity.
doi:10.1007/bf02724562 fatcat:bir4qbjzj5ckxnwmagqhrhipnq