This paper addresses the exponential state explosion problem in heuristic search planning by introducing indexical policies. These generalized policies use registers to hold objects and modes to sequence rules, including a 'choose' rule that commits to a candidate and sets a backtracking point. The authors prove that structural termination not only prevents infinite loops but also bounds execution to polynomial time relative to the number of objects.
- Shifts from storing all states to learning control policies with object registers.
- Structural termination guarantees polynomial execution bounds, not just safety.
- Enables depth-first planning with polynomial space regardless of state space size.
- Reduces search overhead by requiring rules to work for all outcomes after commitment.