Picat Constraint Programming with CP 4

Question 1

In Picat CP, what does `fd_dom(Var, Dom)` return?

Accepted Answer

The domain of Var as a list of values or ranges

Answer

`fd_dom(Var, Dom)` unifies Dom with a representation of all remaining values in Var's finite domain.

Question 2

Which constraint ensures that the values of variables in a list form a permutation of 1..N in Picat CP?

Accepted Answer

all_different(List) with domain 1..N

Answer

Combining `all_different(List)` with each variable's domain set to `1..N` exactly models a permutation constraint.

Question 3

What happens if you post two contradictory constraints, such as `X #= 3` and `X #= 5`, on the same variable in Picat CP?

Accepted Answer

The predicate fails, triggering backtracking

Answer

Constraint propagation detects the empty domain immediately and causes the current goal to fail, which triggers backtracking in the search.

Question 4

In Picat's CP module, the `circuit/1` global constraint is used to model which type of problem?

Accepted Answer

Hamiltonian cycle over a set of successor variables

Answer

`circuit(Succ)` constrains the array Succ so that the successor relation forms a single Hamiltonian cycle visiting every node exactly once.

Question 5

Which predicate tests whether a CP variable is already instantiated (ground) in Picat?

Accepted Answer

ground(Var)

Answer

`ground(Var)` succeeds if Var is fully instantiated and contains no unbound logical variables.

Picat Practice Test