9 Termination in DL Algorithms Each father does not need to be distinct, so an infinite model can be wound up to a finite model (using blocking) Peter x1x1 x2x2 Person 9 father.Person father Person 9 father.Person father Person father 9 father.Person Peter x1x1 Person 9 father.Person father Person 9 father.Person father x 1 is blocked by Peter, so reuse successors of Peter.