Constraint Programming with CP Flashcards

In Picat's CP module, which predicate is used to declare a list of decision variables with a shared domain?

Answer: Vars :: [Low..High]

The `::` operator with a list on the left and a domain expression on the right constrains all variables in the list to that domain.

What does the `indomain` predicate do when called on a CP variable during search in Picat?

Answer: It assigns the variable each value in its domain on backtracking

`indomain(Var)` non-deterministically instantiates Var to successive values in its domain, supporting backtracking search.

Which global constraint in Picat's CP module enforces that no two variables take the same value?

Answer: all_different/1

`all_different(List)` posts a constraint ensuring every pair of variables in the list has distinct values.

In Picat CP, what is the correct way to post a constraint that X is strictly less than Y?

Answer: X #< Y

Arithmetic constraints on CP variables use the `#` prefix operators such as `#`, `#=`, and `#\=`.

What does `solve(Vars)` do in Picat's CP module?

Answer: Labels all variables in Vars with default search options

`solve(Vars)` triggers constraint propagation and labeling for the given variable list using default strategies.

Which labeling option in Picat's CP `solve` tells the solver to choose the variable with the smallest remaining domain first?

Answer: [ff]

`ff` (fail-first) selects the variable with the fewest remaining domain values, reducing early branching failures.

In Picat CP, what is reification of a constraint?

Answer: Converting a constraint to a boolean variable that is 1 iff the constraint holds

Reification links a boolean (0/1) CP variable to a constraint so the variable equals 1 exactly when the constraint is satisfied.