Expressiveness limitation of propositional logic
	n We didn’t keep track of location and time in the KB.  To do this we need more variables: n L1,1 to show that agent in L1,1.  Does this work? n KB contains "physics" sentences for every single square n For every time t and every location [x,y], L x,y  FacingRight t  Forward t  L x+1,y n Rapid proliferation of clauses