`ant_colony_problem_protocol`

Protocol for ant colony optimization problem definitions. A problem object must define the required predicates for constructive solution building on a construction graph (typically a complete graph over a set of nodes, as in the TSP). Optional predicates allow custom stopping and progress reporting.

| Availability: | logtalk_load(ant_colony(loader))

| Author: Paulo Moura | Version: 1:0:0 | Date: 2026-08-16

| Compilation flags: | static

| Dependencies: | (none)

| Remarks: | (none)

| Inherited public predicates: | (none)

.. contents:: :local: :backlinks: top

Public predicates

.. index:: nodes/1 .. _ant_colony_problem_protocol/0::nodes/1:

nodes/1 ^^^^^^^^^^^

Returns the ordered list of nodes that form the construction graph. Solutions are permutations (or paths) over these nodes.

| Compilation flags: | static

| Template: | nodes(Nodes) | Mode and number of proofs: | nodes(-list) - one

.. index:: heuristic/3 .. _ant_colony_problem_protocol/0::heuristic/3:

heuristic/3 ^^^^^^^^^^^^^^^

Returns the heuristic desirability Eta of moving from From to To. Typically the reciprocal of a distance or cost. Must be strictly positive for every pair that can appear in a solution.

| Compilation flags: | static

| Template: | heuristic(From,To,Eta) | Mode and number of proofs: | heuristic(+nonvar,+nonvar,-number) - one

.. index:: solution_cost/2 .. _ant_colony_problem_protocol/0::solution_cost/2:

solution_cost/2 ^^^^^^^^^^^^^^^^^^^

Computes the cost (energy) of a complete solution (tour/path). The algorithm minimizes this value.

| Compilation flags: | static

| Template: | solution_cost(Solution,Cost) | Mode and number of proofs: | solution_cost(+list,-number) - one

.. index:: stop_condition/3 .. _ant_colony_problem_protocol/0::stop_condition/3:

stop_condition/3 ^^^^^^^^^^^^^^^^^^^^

True when the search should stop given the current iteration, best cost found so far, and the cost of the iteration-best solution. Optional. When not defined by the problem, the search runs until the maximum number of iterations is reached.

| Compilation flags: | static

| Template: | stop_condition(Iteration,BestCost,IterationBestCost) | Mode and number of proofs: | stop_condition(+non_negative_integer,+number,+number) - zero_or_one

.. index:: progress/5 .. _ant_colony_problem_protocol/0::progress/5:

progress/5 ^^^^^^^^^^^^^^

Called periodically to report optimization progress. Optional. When not defined by the problem, progress reporting is skipped. The rates are values between 0.0 and 1.0.

| Compilation flags: | static

| Template: | progress(Iteration,BestCost,IterationBestCost,AcceptanceRate,ImprovementRate) | Mode and number of proofs: | progress(+non_negative_integer,+number,+number,+number,+number) - zero_or_one

Protected predicates

(none)

Private predicates

(none)

Operators

(none)

.. seealso::

:ref:`ant_colony(Problem) <ant_colony/1>`