/// <summary>
/// The base constructor.
/// </summary>
/// <param name="domain">The base domain object.</param>
/// <param name="problem">The base problem object.</param>
/// <param name="path">The path used to save files to disk.</param>
public MediationTree(Domain domain, Problem problem, string path)
{
// Store the domain, problem, and path.
this.domain = domain;
this.problem = problem;
this.path = path;
// Store the player's name.
player = problem.Player.ToLower();
// Get and store the NPC names.
npcs = GetNPCs();
// Establish the turn order.
turnOrder = GetTurnOrder();
// Create a new hashtable to store tree edges.
tree = new Hashtable();
// Initialize the session counters.
nodeCounter = 0;
lowestDepth = 0;
goalStateCount = 0;
deadEndCount = 0;
// Create the tree's root node.
MediationTreeNode root = CreateNode(domain, problem, null);
}
/// <summary>
/// Given a mediation tree and a node in the tree, returns the node's world history.
/// </summary>
/// <param name="node">The node.</param>
/// <param name="tree">The tree.</param>
/// <returns>The path through the tree from the root to the node.</returns>
public static List <MediationTreeNode> GetWorldHistory(MediationTreeNode node, MediationTree tree)
{
// Create an empty list object to hold the history.
List <MediationTreeNode> history = new List <MediationTreeNode>();
// Add the node to the world history.
history.Add(node);
// Remember the current node's ID.
int current = node.ID;
// While the current node's parent is not null...
while (tree.GetParent(current) != -1)
{
// Store the current node's parent object.
MediationTreeNode parent = tree.GetNode(tree.GetParent(current));
// Remember the parent's ID.
current = parent.ID;
// Insert the parent node into the world history.
history.Insert(0, parent);
}
// Return the world history.
return(history);
}
/// <summary>
/// Write a node object to disk.
/// </summary>
/// <param name="node">The node's ID.</param>
public void SetNode(MediationTreeNode node)
{
// Given the path and ID, write the node object to disk.
BinarySerializer.SerializeObject <MediationTreeNode>(path + node.ID, node);
// Save the mediation tree.
SaveTree();
}
/// <summary>
/// Given a mediation tree and a node in the tree, returns a event revision domain and problem.
/// </summary>
/// <param name="node">The mediation tree node.</param>
/// <param name="tree">The mediation tree.</param>
/// <returns>The event revision problem and domain for the node.</returns>
public static Tuple <Domain, Problem> GetEventRevisionPair(MediationTreeNode node, MediationTree tree)
{
// Create a clone of the node's original domain.
Domain revisionDomain = node.Domain.Clone() as Domain;
// Create a clone of the node's original problem.
Problem revisionProblem = tree.Root.Problem.Clone() as Problem;
// Get the series of actions and state literals the player has observed.
List <Tuple <Operator, State> > playerKnowledge = GetWorldKnowledge(tree.Player, node, tree);
// Rename the problem to the automated slot.
revisionProblem.Name = "rob";
// Add the initial state tracking literal to the problem's initial state.
revisionProblem.Initial.Add(new Predicate("state-depth", new List <ITerm> {
new Term("depth1", true)
}, true));
revisionDomain.AddTypePair("depth", "state");
revisionDomain.Predicates.Add(new Predicate("state-depth", new List <ITerm> {
new Term("?depth", "", "state")
}, true));
// For every operator in the cloned domain...
foreach (Operator op in revisionDomain.Operators)
{
// Add a state tracking precondition that prevents it from being applied until after the event revision operations have been performed.
op.Preconditions.Add(new Predicate("state-depth", new List <ITerm> {
new Term("depth" + playerKnowledge.Count.ToString(), true)
}, true));
}
// Loop through the action-state pairs in the player knowledge.
for (int i = 1; i < playerKnowledge.Count; i++)
{
// For each of these, add a new state tracker to the list of objects.
revisionProblem.Objects.Add(new Obj("depth" + i.ToString(), "depth"));
// If the player did not observed the current action, add a set of unobserved templates to the list of operators.
if (playerKnowledge[i].First == null)
{
revisionDomain.Operators.AddRange(GetUnobservedActionTemplates(i, tree.GetTurnAtIndex(i - 1), node.Domain, playerKnowledge[i - 1].Second));
}
// If the player did observe the current action, add the observed template to the list of operators.
else
{
revisionDomain.Operators.Add(GetObservedActionTemplate(i, playerKnowledge[i].First));
}
}
// Add the final state tracking object to the problem.
revisionProblem.Objects.Add(new Obj("depth" + playerKnowledge.Count.ToString(), "depth"));
// Return the domain-problem pair.
return(new Tuple <Domain, Problem> (revisionDomain, revisionProblem));
}
/// <summary>
/// Creates a new node object.
/// </summary>
/// <param name="domain">The node's domain.</param>
/// <param name="problem">The node's problem.</param>
/// <param name="incoming">The node's incoming edge.</param>
/// <returns></returns>
public MediationTreeNode CreateNode(Domain domain, Problem problem, MediationTreeEdge incoming)
{
// Create a placeholder for the new node object.
MediationTreeNode node = null;
// If the node is a root, initialize a root node.
if (incoming == null)
{
node = new MediationTreeNode(domain, problem, 0);
}
// Otherwise, it is a child node...
else
{
// Store the current node's ID in the incoming edge.
incoming.Child = ++nodeCounter;
// Create the new node object.
node = new MediationTreeNode(domain, problem, incoming, GetSuccessorState(incoming), incoming.Child, GetDepth(incoming.Parent) + 1);
// Add the edge to the tree hashtable.
tree.Add(incoming.Child, incoming.Parent);
}
// If the node is a goal state, iterate the goal state counter.
if (node.IsGoal)
{
goalStateCount++;
}
// If the node is at a lower depth than the previous record holder, update the depth counter.
if (node.Depth > lowestDepth)
{
lowestDepth = node.Depth;
}
// Find and store the node's outgoing edges.
node.Outgoing = GetOutgoingEdges(node, GetCurrentTurn(node));
// Iterate through the node's outgoing edges.
foreach (GameTreeEdge edge in node.Outgoing)
{
// And add each of them to the unplayed collection.
node.Unplayed.Add(edge);
}
// Save the current node to disk.
SetNode(node);
// Return the current node object.
return(node);
}
/// <summary>
/// The base constructor.
/// </summary>
/// <param name="planner">The planner to use.</param>
/// <param name="domain">The base domain object.</param>
/// <param name="problem">The base problem object.</param>
/// <param name="path">The path used to save files to disk.</param>
/// <param name="domainRevision">Whether to use domain revision.</param>
/// <param name="eventRevision">Whether to use event revision.</param>
/// <param name="superpositionManipulation">Whether to use superposition manipulation.</param>
public MediationTree(Domain domain, Problem problem, string path, bool domainRevision, bool eventRevision, bool superpositionManipulation)
{
// Set the path.
this.path = path;
// Check each path to see if it exists. If not, create the folder.
if (!File.Exists(path))
{
Directory.CreateDirectory(path);
}
// If data already exists, load it from memory.
if (File.Exists(path + "mediationtree"))
{
data = BinarySerializer.DeSerializeObject <MediationTreeData>(path + "mediationtree");
}
// Otherwise, initialize a new tree.
else
{
data.eventRevision = eventRevision;
data.domainRevision = domainRevision;
data.superpositionManipulation = superpositionManipulation;
// Store the domain and problem.
data.domain = domain;
data.problem = problem;
// Store the player's name.
data.player = problem.Player.ToLower();
// Get and store the NPC names.
data.npcs = GetNPCs();
// Establish the turn order.
data.turnOrder = GetTurnOrder();
// Create a new hashtable to store tree edges.
data.tree = new Hashtable();
// Initialize the session counters.
data.nodeCounter = 0;
data.lowestDepth = 0;
data.goalStateCount = 0;
data.deadEndCount = 0;
// Create the tree's root node.
MediationTreeNode root = CreateNode(domain, problem, null);
}
}
/// <summary>
/// Creates a new node or returns the cached version.
/// </summary>
/// <param name="domain">The incoming domain.</param>
/// <param name="problem">The incoming problem.</param>
/// <param name="incoming">The incoming edge.</param>
/// <returns>The child mediation tree node.</returns>
public MediationTreeNode GetNode(Domain domain, Problem problem, MediationTreeEdge incoming)
{
// Return the cached child object if it has already been expanded.
if (incoming.Child >= 0)
{
MediationTreeNode node = GetNode(incoming.Child);
if (node != null)
{
return(node);
}
}
// Otherwise, return a new node.
return(CreateNode(domain, problem, incoming));
}
/// <summary>
/// Returns a list of outgoing edges for a given node.
/// </summary>
/// <param name="node">The node object.</param>
/// <param name="actor">The name of the current actor.</param>
/// <returns>A list of outgoing edges.</returns>
public List <MediationTreeEdge> GetOutgoingEdges(MediationTreeNode node, string actor)
{
List <MediationTreeEdge> outgoing = StateSpaceTools.GetAllPossibleActions(actor, node);
if (!data.superpositionManipulation)
{
return(outgoing);
}
List <MediationTreeEdge> unobservedActions = new List <MediationTreeEdge>();
List <MediationTreeEdge> observedActions = new List <MediationTreeEdge>();
foreach (MediationTreeEdge edge in outgoing)
{
Superposition super = node.State as Superposition;
bool obs = false;
foreach (State state in super.States)
{
if (state.Satisfies(edge.Action.Preconditions))
{
if (KnowledgeAnnotator.Observes(Player, edge.Action, state.Predicates))
{
observedActions.Add(edge);
obs = true;
break;
}
}
}
if (!obs)
{
unobservedActions.Add(edge);
}
}
if (unobservedActions.Count > 0)
{
VirtualMediationTreeEdge super = new VirtualMediationTreeEdge();
foreach (MediationTreeEdge unobserved in unobservedActions)
{
super.Actions.Add(unobserved.Action as Operator);
}
super.Parent = node.ID;
observedActions.Add(super);
}
return(observedActions);
}
/// <summary>
/// Given a planner, a mediation tree node, and a mediation tree, return an event revision plan and state to set for the node.
/// </summary>
/// <param name="planner">The planner to use.</param>
/// <param name="node">The current node in the mediation tree.</param>
/// <param name="tree">The mediation tree.</param>
/// <returns>A plan state pair for the current node.</returns>
public static void EventRevision(Planner planner, MediationTreeNode node, MediationTree tree)
{
// Compute the event revision problem and domain for the current node.
Tuple <Domain, Problem> pair = GetEventRevisionPair(node, tree);
// Use the planner to find an event revision plan.
Plan plan = PlannerInterface.Plan(planner, pair.First, pair.Second);
if (plan.Steps.Count > 0)
{
Tuple <Plan, State> planState = GetPlanStatePair(plan, node, tree);
node.Plan = planState.First;
node.State = planState.Second;
node.Problem.Initial = node.State.Predicates;
}
}
/// <summary>
/// Given an event revision plan, a mediation tree node, and a mediation tree, returns the plan and state to set in the node.
/// </summary>
/// <param name="plan">The full event revision plan from the original initial state.</param>
/// <param name="node">The current node in the mediation tree.</param>
/// <param name="tree">The mediation tree object.</param>
/// <returns>The current state to set in the node after event revision and the plan from the state forward.</returns>
public static Tuple <Plan, State> GetPlanStatePair(Plan plan, MediationTreeNode node, MediationTree tree)
{
// Reformat the event revision plan to get a regular plan.
Plan formattedPlan = ReformatPlan(plan, tree.Root.Domain, tree.Root.Problem);
// Create a list to hold event revision steps.
List <IOperator> pastSteps = new List <IOperator>();
// Create another list to hold future plan steps.
List <IOperator> futureSteps = new List <IOperator>();
// Loop through the steps in the formatted event revision plan...
for (int i = 0; i < formattedPlan.Steps.Count; i++)
{
// If the step happened before the current state, it is an event revision step.
if (i < node.Depth)
{
pastSteps.Add(formattedPlan.Steps[i]);
}
// If the step happens at or after the current state, it is a future plan step.
else
{
futureSteps.Add(formattedPlan.Steps[i]);
}
}
// Create a new state object by cloning the initial state of the original planning problem.
State current = tree.Root.State.Clone() as State;
// Loop through each of the event revision steps...
foreach (IOperator step in pastSteps)
{
// And update the state object by applying the action.
current = new State(current.ApplyAction(step as Operator, node.Problem.Objects));
}
// Return the future plan along with the computed state.
return(new Tuple <Plan, State>(new Plan(node.Domain, node.Problem, futureSteps), current));
}
/// <summary>
/// Get the current turn taker.
/// </summary>
/// <param name="node">The current node.</param>
/// <returns>The name of the character who gets to act.</returns>
private string GetCurrentTurn(MediationTreeNode node)
{
// Returns the character who gets to act at this level.
return(data.turnOrder[node.Depth % data.turnOrder.Count]);
}
/// <summary>
/// Allows custom plans to be passed in.
/// </summary>
/// <param name="domain">The node's domain.</param>
/// <param name="problem">The node's problem.</param>
/// <param name="incoming">The node's incoming edge.</param>
/// <returns>A new tree node.</returns>
private MediationTreeNode CreateNode(Domain domain, Problem problem, MediationTreeEdge incoming, Plan plan)
{
// Create a placeholder for the new node object.
MediationTreeNode node = null;
// If the node is a root, initialize a root node.
if (incoming == null)
{
if (!data.superpositionManipulation)
{
node = new MediationTreeNode(domain, problem, 0);
}
else
{
node = new VirtualMediationTreeNode(domain, problem, 0);
}
}
// Otherwise, it is a child node...
else
{
// Store the current node's ID in the incoming edge.
incoming.Child = ++data.nodeCounter;
if (!data.superpositionManipulation)
{
node = new MediationTreeNode(domain, problem, incoming, GetSuccessorState(incoming), plan, incoming.Child, GetDepth(incoming.Parent) + 1);
}
else
{
node = new VirtualMediationTreeNode(domain, problem, incoming, GetSuccessorSuperposition(incoming), plan, incoming.Child, GetDepth(incoming.Parent) + 1);
}
// Add the edge to the tree hashtable.
data.tree[incoming.Child] = incoming.Parent;
MediationTreeNode parent = GetNode(incoming.Parent);
if (incoming.Action != null)
{
parent.Outgoing.Find(x => x.Action.Equals(incoming.Action)).Child = node.ID;
}
else
{
foreach (MediationTreeEdge edge in parent.Outgoing)
{
if (edge is VirtualMediationTreeEdge)
{
if ((edge as VirtualMediationTreeEdge).Equals(incoming as VirtualMediationTreeEdge))
{
edge.Child = node.ID;
}
}
}
}
SetNode(parent);
if (data.superpositionManipulation)
{
Superposition super = node.State as Superposition;
super.States = SuperpositionManipulator.Collapse(data.player, node as VirtualMediationTreeNode, SuperpositionChooser.ChooseUtility);
node.State = super;
}
}
// If the node is a goal state, iterate the goal state counter.
if (node.IsGoal)
{
data.goalStateCount++;
}
// If the node is a dead end, iterate the dead end counter.
if (node.DeadEnd)
{
if (data.eventRevision)
{
EventRevisor.EventRevision(Planner.FastDownward, node, this);
}
if (node.DeadEnd && data.domainRevision)
{
DomainRevisor.DomainRevision(Planner.FastDownward, node, this);
}
if (node.DeadEnd)
{
data.deadEndCount++;
}
}
// If the node is at a lower depth than the previous record holder, update the depth counter.
if (node.Depth > data.lowestDepth)
{
data.lowestDepth = node.Depth;
}
// If the node is not a dead end.
if (!node.DeadEnd)
{
// Find and store the node's outgoing edges.
node.Outgoing = GetOutgoingEdges(node, GetCurrentTurn(node));
}
// Save the current node to disk.
SetNode(node);
// Return the current node object.
return(node);
}
public static void DomainRevision(Planner planner, MediationTreeNode node, MediationTree tree)
{
// Store the incoming action.
Operator incoming = node.Incoming.Action as Operator;
// Create a new plan object.
Plan newPlan = new Plan();
List <Tuple <Operator, State> > knowledge = EventRevisor.GetWorldKnowledge(tree.Player, node, tree);
knowledge.RemoveAt(knowledge.Count - 1);
List <Operator> observedActions = new List <Operator>();
foreach (Tuple <Operator, State> pair in knowledge)
{
if (pair.First != null)
{
if (pair.First.Name.Equals(incoming.Name))
{
observedActions.Add(pair.First);
}
}
}
// Examine each exceptional effect.
foreach (Predicate effect in incoming.ExceptionalEffects)
{
// Create a new domain object.
Domain newDomain = node.Domain.Clone() as Domain;
newDomain.Operators = new List <IOperator>();
// If the current effect is conditional...
if (incoming.IsConditional(effect))
{
bool observed = false;
// If the conditional effect has not been observed by the player.
foreach (Operator action in observedActions)
{
if (!observed)
{
foreach (IAxiom conditional in action.Conditionals)
{
if (conditional.Effects.Contains(effect) && !observed)
{
observed = true;
}
}
}
}
// Remove the conditional effect from the domain.
if (!observed)
{
// Copy the current operator templates into a list.
List <IOperator> templates = new List <IOperator>();
foreach (IOperator templ in node.Domain.Operators)
{
templates.Add(templ.Clone() as IOperator);
}
// Create a clone of the incoming action's unbound operator template.
IOperator temp = incoming.Template() as Operator;
// Find the incoming action template in the domain list.
Operator template = templates.Find(t => t.Equals(temp)) as Operator;
// Remove the incoming action template from the domain list.
templates.Remove(template);
// Create a clone of the incoming action.
Operator clone = incoming.Clone() as Operator;
// Create a list of conditional effects to remove from the template.
List <IAxiom> remove = new List <IAxiom>();
foreach (IAxiom conditional in clone.Conditionals)
{
if (conditional.Effects.Contains(effect))
{
remove.Add(conditional);
}
}
// Remove each conditional effect from the template.
foreach (IAxiom rem in remove)
{
template.Conditionals.Remove(rem.Template() as IAxiom);
}
// Add the modified template to the domain list.
templates.Add(template);
// Push the modified list to the new domain object.
newDomain.Operators = templates;
// Clone the modified incoming action template.
Operator newAction = template.Clone() as Operator;
// Bind the cloned action with the incoming action's bindings.
newAction.Bindings = incoming.Bindings;
MediationTreeEdge newEdge = new MediationTreeEdge(newAction, ActionType.Exceptional, node.Incoming.Parent, node.ID);
Problem newProblem = node.Problem.Clone() as Problem;
newProblem.Initial = tree.GetSuccessorState(newEdge).Predicates;
// Find a new plan.
newPlan = PlannerInterface.Plan(planner, newDomain, newProblem);
// If the modified domain can accommodate the player's action...
if (newPlan.Steps.Count > 0)
{
node.Plan = newPlan;
node.Incoming.Action = newAction;
node.State = tree.GetSuccessorState(node.Incoming);
node.Domain = newDomain;
}
}
}
}
}
/// <summary>
/// Returns a list of outgoing edges for a given node.
/// </summary>
/// <param name="node">The node object.</param>
/// <param name="actor">The name of the current actor.</param>
/// <returns>A list of outgoing edges.</returns>
public List <MediationTreeEdge> GetOutgoingEdges(MediationTreeNode node, string actor)
{
// If it's the player's turn, return their list of actions.
return(StateSpaceTools.GetAllPossibleActions(actor, node));
}
/// <summary>
/// Given a character, node, and tree, returns the character's knowledge of the world history.
/// </summary>
/// <param name="character">The character.</param>
/// <param name="node">The node that corresponds to the current state.</param>
/// <param name="tree">The mediation tree.</param>
/// <returns>A list of action-state pairs that represent what the character knows.</returns>
public static List <Tuple <Operator, State> > GetWorldKnowledge(string character, MediationTreeNode node, MediationTree tree)
{
// An object to hold the character's knowledge of the world history.
List <Tuple <Operator, State> > knowledge = new List <Tuple <Operator, State> >();
// Get the objective world history.
List <MediationTreeNode> history = GetWorldHistory(node, tree);
// Loop through the nodes in the world history branch...
foreach (MediationTreeNode current in history)
{
// Create a new action.
Operator action = null;
// Make sure the current node is not the root.
if (current.Incoming != null)
{
// Check if the character observes the incoming action.
if (KnowledgeAnnotator.Observes(character, current.Incoming.Action, current.State.Predicates))
{
// If so, remember that the character observed the action.
action = current.Incoming.Action.Clone() as Operator;
}
}
// Create a new state consisting only of terms the character observed.
State state = new State(KnowledgeAnnotator.FullKnowledgeState(tree.Root.Domain.Predicates, tree.Root.Problem.ObjectsByType, current.State.Predicates, character));
// Store the observed action-state pair as a tuple.
knowledge.Add(new Tuple <Operator, State>(action, state));
}
// Return the sequence of observed action-state pairs.
return(knowledge);
}
/// <summary>
/// Chooses a set of superposed states based on a simple utility function.
/// </summary>
/// <param name="observations">The sets of possible literals observed by the player mapped to the sets of states consistent with each observation.</param>
/// <param name="node">The current node in the mediation tree.</param>
/// <returns>A set of states chosen by the system.</returns>
public static HashSet <State> ChooseUtility(Dictionary <List <IPredicate>, HashSet <State> > observations, MediationTreeNode node)
{
// Create a dictionary of utilities that map to sets of states.
Dictionary <float, HashSet <State> > utilities = new Dictionary <float, HashSet <State> >();
// If there is more than one observation the player can make.
if (observations.Keys.Count > 1)
{
// Loop through each set of observed literals.
foreach (List <IPredicate> key in observations.Keys)
{
// Store how many wins and losses the set of states has.
float wins = 0;
float losses = 0;
// Loop through each state in the set of states consistent with the current observation.
foreach (State state in observations[key])
{
// Store whether we are at a goal state.
bool satisfiesGoal = false;
// Store whether a goal state is reached by the planner.
bool win = true;
// Check whether the current state is a goal state.
if (state.Satisfies(node.Problem.Goal))
{
satisfiesGoal = true;
}
// Create a new problem object for the current state.
Problem problem = new Problem("rob", node.Problem.OriginalName, node.Problem.Domain, node.Problem.Player, node.Problem.Objects, state.Predicates, node.Problem.Intentions, node.Problem.Goal);
// Find a plan from the current state if one exists.
Plan plan = PlannerInterface.Plan(Planner.FastDownward, node.Domain, problem);
// Check if a goal has been reached by the state or the plan.
if (plan.Steps.Count == 0 && !satisfiesGoal)
{
win = false;
}
// Record the win or loss.
if (win)
{
wins++;
}
else
{
losses++;
}
}
// Initialize the utility.
float utility = 0;
// If none of the states lost, go ahead and return the current state.
if (losses == 0)
{
return(observations[key]);
}
// Otherwise, record the utility as wins divided by losses.
else
{
utility = wins / losses;
}
// Map the utility onto the current state set in the dictionary.
utilities[utility] = observations[key];
}
}
else
{
// Store the single set of observations.
List <IPredicate> key = observations.Keys.ToArray()[0];
// Use the observations to return the single set of states.
return(observations[key]);
}
// Return the set of states with the highest utility value.
return(utilities[utilities.Keys.Max()]);
}
/// <summary>
/// Randomly chooses a set of superposed states.
/// </summary>
/// <param name="observations">The sets of possible literals observed by the player mapped to the sets of states consistent with each observation.</param>
/// <param name="node">The current node in the mediation tree.</param>
/// <returns>A set of states chosen by the system.</returns>
public static HashSet <State> ChooseRandom(Dictionary <List <IPredicate>, HashSet <State> > observations, MediationTreeNode node)
{
// Create a new Random object.
Random rand = new Random();
// Choose a random number to map onto a key in the observation dictionary.
int pickNum = rand.Next(0, observations.Keys.Count);
// Grab the observation set associated with the chosen integer.
List <IPredicate> pickPreds = observations.Keys.ToArray()[pickNum];
// Return the set of states consistent with the observation.
return(observations[pickPreds]);
}
