Show sorted predicates in Clingo

Question

I have a predicate pred/2, how do I #show this predicate in the answer that is sorted by the first argument, given that the first argument will be numerical?

I couldn't find any relevant documentation on how Clingo orders its output predicates.

Answer 1

The clingo system allows you to solve exponentially hard problems. It has no sophisticated options to sort the output. Use the clingo python API or a postprocessor to do so.

Answer 2

Depending on your use case... you can encourage the discovered answer sets to be sorted (and adjacent) if you structure its choices:

% Equivalent to: { pred(N) : N=1..100 }.
{ pred(1) }.
{ pred(N+1) } :- pred(N), N < 100.

Now the answer sets containing pred(_) will always start at 1 and be sequential, and will be sorted in the output.

In my brief experiments, the drawback was ~3% increase in solution time.