Extreme Goal Sequence Issues

[benhawkinsicon]

I noticed this when trying out extreme goals, and was able to quickly reproduce by modifying the ExtremeHappinessIncrementer.cs example. It appears as though actions whose postconditions are non-arithmetic will always satisfy an ExtremeGoal's MeetsGoal, which leads to infinite looping if any actions are non-arithmetic.

In my case, I need to create a sequence leading to an arithmetic action, where normal postconditions are necessary to plan for the arithmetic action's preconditions.

Below is a minimal modification where I make "Seek Greater Happiness" have a dummy postcondition, and it is chosen continuously over the arithmetic action.

        internal static void Run() {
            _ = new DefaultLogger();
            Agent agent = new(
                name: "Happiness Agent",
                state: new() {
                    { "happiness", 0 },
                },
                goals: new() {
                    new ExtremeGoal(
                        name: "Maximize Happiness",
                        desiredState: new() {
                            { "happiness", true }
                        })
                },
                actions: new() {
                    new(
                        name: "Seek Happiness",
                        executor: SeekHappinessAction,
                        arithmeticPostconditions: new() {
                            {
                                "happiness",
                                1
                            }
                        }
                    ),
                    new(
                        name: "Seek Greater Happiness",
                        executor: SeekGreaterHappinessAction,
                        postconditions: new()
                        {
                            { "anything", true }
                        }
                    ),
                }
            );
            while (agent.State["happiness"] is int happiness && happiness != 10) {
                agent.Step();
                Console.WriteLine($"NEW HAPPINESS IS {agent.State["happiness"]}");
            }
        }

And i've tracked the execution to this (seemingly incorrect) evaluation of MeetsGoal. I am wondering if it is because this method only checks isLowerThan / isHigherThan when it should be isLowerThanOrEqualTo since no arithmetic difference means no progress towards the extreme goal is made.

            // ActionAStar.cs (line 47)
            while (frontier.Count > 0) {
                var current = frontier.Dequeue();
                // this is always true for non-arithmetic postconditions
                if (MeetsGoal(current, start)) { 
                    FinalPoint = current;
                    break;
                }
                foreach (var next in graph.Neighbors(current)) {
                    float newCost = CostSoFar[current] + next.Cost(current.State);
                    if (newCost > costMaximum) continue;
                    if (!CostSoFar.ContainsKey(next) || newCost < CostSoFar[next]) {
                        CostSoFar[next] = newCost;
                        float priority = newCost + Heuristic(next, goal, current);
                        frontier.Enqueue(next, priority);
                        CameFrom[next] = current;
                        Agent.TriggerOnEvaluatedActionNode(next, CameFrom);
                    }
                }
            }

Though I might just be missing something

[caesuric]

Thank you for your PR, which appears to fix this. I'll close this since it appears to be fixed. Feel free to reopen if the issue comes up again.

[caesuric]

This fix is in 0.11.4.