public string Predict(Example e)
{
string prediction = "~" + e.TargetValue();
if (null != currentBestHypothesis)
{
var etp = new FOLExample(folDSDomain, e, 0);
kb.Clear();
kb.tell(etp.GetDescription());
kb.tell(currentBestHypothesis.GetHypothesis());
IInferenceResult ir = kb.Ask(etp.GetClassification());
if (ir.IsTrue())
{
if (trueGoalValue.Equals(e.TargetValue()))
{
prediction = e.TargetValue();
}
}
else if (ir.IsPossiblyFalse() || ir.IsUnknownDueToTimeout())
{
if (!trueGoalValue.Equals(e.TargetValue()))
{
prediction = e.TargetValue();
}
}
}
return(prediction);
}
public void testAddRuleAndFact()
{
weaponsKB.tell("(Missile(x) => Weapon(x))");
Assert.AreEqual(1, weaponsKB.getNumberRules());
weaponsKB.tell("American(West)");
Assert.AreEqual(1, weaponsKB.getNumberRules());
Assert.AreEqual(1, weaponsKB.getNumberFacts());
}
public void testExhaustsSearchSpace()
{
// Taken from AIMA pg 679
FOLDomain domain = new FOLDomain();
domain.addPredicate("alternate");
domain.addPredicate("bar");
domain.addPredicate("fri_sat");
domain.addPredicate("hungry");
domain.addPredicate("patrons");
domain.addPredicate("price");
domain.addPredicate("raining");
domain.addPredicate("reservation");
domain.addPredicate("type");
domain.addPredicate("wait_estimate");
domain.addPredicate("will_wait");
domain.addConstant("Some");
domain.addConstant("Full");
domain.addConstant("French");
domain.addConstant("Thai");
domain.addConstant("Burger");
domain.addConstant("$");
domain.addConstant("_30_60");
domain.addConstant("X0");
FOLParser parser = new FOLParser(domain);
// The hypothesis
String c1 = "patrons(v,Some)";
String c2 = "patrons(v,Full) AND (hungry(v) AND type(v,French))";
String c3 = "patrons(v,Full) AND (hungry(v) AND (type(v,Thai) AND fri_sat(v)))";
String c4 = "patrons(v,Full) AND (hungry(v) AND type(v,Burger))";
String sh = "FORALL v (will_wait(v) <=> (" + c1 + " OR (" + c2
+ " OR (" + c3 + " OR (" + c4 + ")))))";
Sentence hypothesis = parser.parse(sh);
Sentence desc = parser
.parse("(((((((((alternate(X0) AND NOT(bar(X0))) AND NOT(fri_sat(X0))) AND hungry(X0)) AND patrons(X0,Full)) AND price(X0,$)) AND NOT(raining(X0))) AND NOT(reservation(X0))) AND type(X0,Thai)) AND wait_estimate(X0,_30_60))");
Sentence classification = parser.parse("will_wait(X0)");
FOLKnowledgeBase kb = new FOLKnowledgeBase(domain,
new FOLOTTERLikeTheoremProver(false));
kb.tell(hypothesis);
kb.tell(desc);
InferenceResult ir = kb.ask(classification);
Assert.IsFalse(ir.isTrue());
Assert.IsTrue(ir.isPossiblyFalse());
Assert.IsFalse(ir.isUnknownDueToTimeout());
Assert.IsFalse(ir.isPartialResultDueToTimeout());
Assert.AreEqual(0, ir.getProofs().Count);
}
// TODO - Implement!!!
public Hypothesis currentBestLearning(ICollection <FOLExample> examples)
{
// TODO-use the default from pg 769 for now.
string c1 = "patrons(v,Some)";
string c2 = "patrons(v,Full) AND (hungry(v) AND type(v,French))";
string c3 = "patrons(v,Full) AND (hungry(v) AND (type(v,Thai) AND fri_sat(v)))";
string c4 = "patrons(v,Full) AND (hungry(v) AND type(v,Burger))";
string sh = "FORALL v (will_wait(v) <=> (" + c1 + " OR (" + c2
+ " OR (" + c3 + " OR (" + c4 + ")))))";
Hypothesis h = new Hypothesis(kbForLearning.tell(sh));
return(h);
}
// START-InferenceProcedure
/**
* <code>
* function FOL-FC-ASK(KB, alpha) returns a substitution or false
* inputs: KB, the knowledge base, a set of first order definite clauses
* alpha, the query, an atomic sentence
* </code>
*/
public InferenceResult ask(FOLKnowledgeBase KB, Sentence query)
{
// Assertions on the type of queries this Inference procedure
// supports
if (!(query is AtomicSentence))
{
throw new ArgumentException(
"Only Atomic Queries are supported.");
}
FCAskAnswerHandler ansHandler = new FCAskAnswerHandler();
Literal alpha = new Literal((AtomicSentence)query);
// local variables: new, the new sentences inferred on each iteration
List <Literal> newSentences = new List <Literal>();
// Ensure query is not already a know fact before
// attempting forward chaining.
List <Dictionary <Variable, Term> > answers = KB.fetch(alpha);
if (answers.Count > 0)
{
ansHandler.addProofStep(new ProofStepFoChAlreadyAFact(alpha));
ansHandler.setAnswers(answers);
return(ansHandler);
}
// repeat until new is empty
do
{
// new <- {}
newSentences.Clear();
// for each rule in KB do
// (p1 ^ ... ^ pn => q) <-STANDARDIZE-VARIABLES(rule)
foreach (Clause impl in KB.getAllDefiniteClauseImplications())
{
Clause impl2 = KB.standardizeApart(impl);
// for each theta such that SUBST(theta, p1 ^ ... ^ pn) =
// SUBST(theta, p'1 ^ ... ^ p'n)
// --- for some p'1,...,p'n in KB
foreach (Dictionary <Variable, Term> theta in KB.fetch(invert(new List <Literal>(impl2
.getNegativeLiterals()))))
{
// q' <- SUBST(theta, q)
Literal qPrime = KB.subst(theta, impl.getPositiveLiterals()
[0]);
// if q' does not unify with some sentence already in KB or
// new then do
if (!KB.isRenaming(qPrime) &&
!KB.isRenaming(qPrime, newSentences))
{
// add q' to new
newSentences.Add(qPrime);
ansHandler.addProofStep(impl, qPrime, theta);
// theta <- UNIFY(q', alpha)
Dictionary <Variable, Term> theta2 = KB.unify(qPrime.getAtomicSentence(), alpha
.getAtomicSentence());
// if theta is not fail then return theta
if (null != theta2)
{
foreach (Literal l in newSentences)
{
Sentence s = null;
if (l.isPositiveLiteral())
{
s = l.getAtomicSentence();
}
else
{
s = new NotSentence(l.getAtomicSentence());
}
KB.tell(s);
}
ansHandler.setAnswers(KB.fetch(alpha));
return(ansHandler);
}
}
}
}
// add new to KB
foreach (Literal l in newSentences)
{
Sentence s = null;
if (l.isPositiveLiteral())
{
s = l.getAtomicSentence();
}
else
{
s = new NotSentence(l.getAtomicSentence());
}
KB.tell(s);
}
} while (newSentences.Count > 0);
// return false
return(ansHandler);
}
public void testBinaryResolventsOrderDoesNotMatter()
{
// This is a regression test, to ensure
// the ordering of resolvents does not matter.
// If the order ends up mattering, then likely
// a problem was introduced in the Clause class
// unifier, or related class.
// Set up the initial set of clauses based on the
// loves animal domain as it contains functions
// new clauses will always be created (i.e. is an
// infinite universe of discourse).
FOLKnowledgeBase kb = new FOLKnowledgeBase(DomainFactory.lovesAnimalDomain());
kb.tell("FORALL x (FORALL y (Animal(y) => Loves(x, y)) => EXISTS y Loves(y, x))");
kb.tell("FORALL x (EXISTS y (Animal(y) AND Kills(x, y)) => FORALL z NOT(Loves(z, x)))");
kb.tell("FORALL x (Animal(x) => Loves(Jack, x))");
kb.tell("(Kills(Jack, Tuna) OR Kills(Curiosity, Tuna))");
kb.tell("Cat(Tuna)");
kb.tell("FORALL x (Cat(x) => Animal(x))");
ISet <Clause> clauses = CollectionFactory.CreateSet <Clause>();
clauses.AddAll(kb.getAllClauses());
ISet <Clause> newClauses = CollectionFactory.CreateSet <Clause>();
long maxRunTime = 30 * 1000; // 30 seconds
IDateTime finishTime = CommonFactory.Now().AddMilliseconds(maxRunTime);
do
{
clauses.AddAll(newClauses);
newClauses.Clear();
Clause[] clausesA = clauses.ToArray();
for (int i = 0; i < clausesA.Length; ++i)
{
Clause cI = clausesA[i];
for (int j = 0; j < clausesA.Length; j++)
{
Clause cJ = clausesA[j];
newClauses.AddAll(cI.getFactors());
newClauses.AddAll(cJ.getFactors());
ISet <Clause> cIresolvents = cI.binaryResolvents(cJ);
ISet <Clause> cJresolvents = cJ.binaryResolvents(cI);
if (!cIresolvents.SequenceEqual(cJresolvents))
{
System.Console.WriteLine("cI=" + cI);
System.Console.WriteLine("cJ=" + cJ);
System.Console.WriteLine("cIR=" + cIresolvents);
System.Console.WriteLine("cJR=" + cJresolvents);
Assert.Fail("Ordering of binary resolvents has become important, which should not be the case");
}
foreach (Clause r in cIresolvents)
{
newClauses.AddAll(r.getFactors());
}
if (CommonFactory.Now().BiggerThan(finishTime))
{
break;
}
}
if (CommonFactory.Now().BiggerThan(finishTime))
{
break;
}
}
} while (CommonFactory.Now().SmallerThan(finishTime));
}
// If your activity returns a value, derive from CodeActivity<TResult>
// and return the value from the Execute method.
protected override void Execute(CodeActivityContext context)
{
FOLKnowledgeBase kb = context.GetValue <FOLKnowledgeBase>(KB);
kb.tell(TellText);
}
