11.3 There are many ways to characterize planners. For each of the following dichotomies, explain what they mean, and how the choice between them affects the efficiency and completeness of a planner.

a. Situation space vs. plan space.

b. Progressive vs. regressive

c. Refinement vs. debugging.

d. Least commitment vs. more commitment.

e. Bound variables vs. unbound variables.

f. Total order vs. partial order.
g. Interleaved vs. noninterleaved.
h. Unambiguous preconditions vs. ambiguous preconditions.
i. Systematic vs. unsystematic.