Picat Constraint Programming with CP 5

Question 1

In Picat CP, what does the `among/4` global constraint enforce?

Accepted Answer

That between Low and High variables in a list take values from a given set

Answer

`among(Low, High, Vars, Values)` constrains that the number of variables in Vars whose values belong to Values is between Low and High.

Question 2

Which solve option in Picat CP enables randomized restarts to escape local search traps?

Accepted Answer

[rand_val]

Answer

`rand_val` is a value-selection heuristic that picks values randomly, helping escape symmetric or structured dead ends.

Question 3

When modeling the N-Queens problem in Picat CP, which two all_different constraints are typically combined?

Accepted Answer

all_different on column positions and all_different on both diagonals

Answer

Queens must differ in column positions and on both the positive and negative diagonals, requiring three all_different constraints in total.

Question 4

What does `fd_size(Var, Size)` return in Picat's CP module?

Accepted Answer

The number of values currently in Var's domain

Answer

`fd_size(Var, Size)` unifies Size with the cardinality of Var's current finite domain.

Question 5

In Picat CP, what does posting `X #>= Y #<=> B` accomplish (assuming B is a 0/1 variable)?

Accepted Answer

It sets B to 1 if X >= Y, and to 0 otherwise

Answer

The `#<=>` operator creates a reified constraint, making B equal 1 exactly when the constraint X #>= Y is satisfied.

Picat Practice Test