//backward chain
public Clause Infer(string goal_variable, List <Clause> unproved_conditions)
{
Clause conclusion = null;
var goal_stack = new List <Rule>();
foreach (var rule in Rules)
{
var consequent = rule.GetConsequent();
if (consequent.Variable == goal_variable)
{
goal_stack.Add(rule);
}
}
foreach (var rule in Rules)
{
rule.FirstAntecedent();
var goal_reached = true;
while (rule.HasNextAntecedents())
{
var antecedent = rule.NextAntecedent();
if (!WorkingMemory.IsFact(antecedent))
{
if (WorkingMemory.IsNotFact(antecedent)) //conflict with memory
{
goal_reached = false;
break;
}
if (IsFact(antecedent, unproved_conditions)) //deduce to be a fact
{
WorkingMemory.AddFact(antecedent);
}
else //deduce to not be a fact
{
goal_reached = false;
break;
}
}
}
if (goal_reached)
{
conclusion = rule.GetConsequent();
break;
}
}
return(conclusion);
}
public void Fire(WorkingMemory wm)
{
if (!wm.IsFact(Consequent))
{
wm.AddFact(Consequent);
}
Fired = true;
}
/// <summary>
/// Add another know fact into the working memory
/// </summary>
/// <param name="c"></param>
public void AddFact(Clause c)
{
WorkingMemory.AddFact(c);
}