Reasons Search is Needed
1) An achieved goal can be clobbered by a subsequent goal.
- e.g., achieving dr = off and then vlv = open clobbers dr = off.
2) Two goals compete for the same variable in their subgoals.
- e.g., latch1 and latch2 compete for the position of switch sw.
3) A state transition of a subgoal var has irreversible effect.
- e.g., assume sw can be used once, then latch1 must be latched before latch2.
To achieve reactivity we eliminate all forms of search.