Picat The Planner Module 5

Question 1

When would you choose `best_plan` over `plan` in a Picat program?

Accepted Answer

When you need the minimum-cost solution, not just any valid solution

Answer

`best_plan` exhausts the search to guarantee cost optimality, while `plan` returns the first solution it finds which may not be cheapest.

Question 2

In what form does the Plan variable appear after a successful call to `plan/2`?

Accepted Answer

A Picat list of action terms, e.g., [Action1, Action2, ...]

Answer

The Plan is unified with a standard Picat list where each element is the Action term from the corresponding `action/4` call.

Question 3

What is printed when you call `writeln(Plan)` after `plan(InitState, Plan)` succeeds with a three-step plan?

Accepted Answer

A list with three elements, one per action

Answer

Plan is a list of action terms, so `writeln` outputs something like `[action1,action2,action3]` with one element per step.

Question 4

If the initial state already satisfies `final/1`, what does `plan/2` return?

Accepted Answer

An empty list, since no actions are needed

Answer

When the start state is already a goal state, `plan/2` succeeds immediately with Plan = [], reflecting that zero actions are required.

Question 5

Which statement best describes how `plan/3` and `plan/4` differ?

Accepted Answer

plan/4 also unifies a variable with the total plan cost; plan/3 does not

Answer

`plan(State, Limit, Plan, Cost)` adds a fourth argument that is unified with the total accumulated cost of the returned plan.

Picat Practice Test