Picat General 3

Question 1

In Picat's constraint module `cp`, which predicate declares an integer decision variable with a domain?

Accepted Answer

X :: Lo..Hi

Answer

The `::` operator assigns a finite-domain range to a decision variable, e.g., `X :: 1..10` constrains X to integers 1 through 10.

Question 2

What does `solve([ff], Vars)` do in Picat's constraint solver?

Accepted Answer

Searches for values satisfying constraints using the first-fail heuristic

Answer

`solve` with option `ff` (first-fail) selects the variable with the smallest remaining domain first, improving search efficiency.

Question 3

Which Picat built-in computes the length of a list?

Accepted Answer

length(List, Len)

Answer

`length(List, Len)` unifies Len with the number of elements in List, and can also generate a list of free variables when Len is given.

Question 4

How does Picat's tabling differ from standard Prolog memoization libraries?

Accepted Answer

Tabling is built into the language with the `table` directive and handles cycles automatically

Answer

Picat's `table` directive enables SLG-resolution tabling that correctly handles cyclic calls and avoids infinite loops without programmer intervention.

Question 5

What is the output of `writeln(2 ** 10)` in Picat?

Accepted Answer

1024

Answer

The `**` operator in Picat performs integer exponentiation when both operands are integers, so 2**10 evaluates to 1024.

Picat Practice Test

Picat Practice Test

Picat General 3