General Flashcards

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

Answer: X :: Lo..Hi

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

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

Answer: Searches for values satisfying constraints using the first-fail heuristic

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

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

Answer: length(List, Len)

`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.

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

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

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

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

Answer: 1024

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

In Picat, which construct allows pattern matching directly in a function/predicate head?

Answer: Multiple clauses with different head patterns

Picat allows multiple clauses for the same predicate/function, each with a distinct head pattern that is tried in order, enabling structural pattern matching.

Which keyword in Picat is used to import a module at the top of a file?

Answer: import

The `import` declaration at the top of a Picat file makes predicates from a named module available in the current file.