  We consider the (3+1)-dimensional locally finite gravity model proposed by 't
Hooft. In particular we revisit the problem of resolving collisions of string
defects. We provide a new geometric description of the configurations of
strings using piecewise flat manifolds, and use it to resolve a more general
class of collisions. We argue that beyond certain bounds for the
deficiency/surplus angles no resolutions may be found that satisfy the imposed
causality conditions.
