Examples with IntensionalSet com.sri.ai.expresso.api.IntensionalSet used on opensource projects

Example 46 with IntensionalSet

use of com.sri.ai.expresso.api.IntensionalSet in project aic-expresso by aic-sri-international.

the class IntersectionIntensionalSetsSimplifier method simplify.

public static Expression simplify(Expression expression, Context context) {
    Expression result = expression;
    if (expression.hasFunctor(FunctorConstants.INTERSECTION)) {
        List<Expression> intensionalMultiSetArgs = new ArrayList<>();
        List<Expression> nonIntensionalMultiSetArgs = new ArrayList<>();
        for (Expression arg : expression.getArguments()) {
            if (Sets.isIntensionalMultiSet(arg)) {
                intensionalMultiSetArgs.add(arg);
            } else {
                nonIntensionalMultiSetArgs.add(arg);
            }
        }
        if (intensionalMultiSetArgs.size() > 1) {
            boolean resultIsEmptySet = false;
            IntensionalSet intersectedMultiSet = (IntensionalSet) intensionalMultiSetArgs.get(0);
            for (int i = 1; i < intensionalMultiSetArgs.size() && !resultIsEmptySet; i++) {
                IntensionalSet otherMultiSet = standardizeApartIntensionalSets((IntensionalSet) intensionalMultiSetArgs.get(i), intersectedMultiSet, context);
                // {{ (on I1) H1 : C1 }} intersection {{ (on I2) H2 : C2 }}
                // ---->
                // {{ (on I1) H1 : C1 and evaluate(there exists I2 : C2 and H2 = H1) }}
                IndexExpressionsSet i1 = intersectedMultiSet.getIndexExpressions();
                IndexExpressionsSet i2 = otherMultiSet.getIndexExpressions();
                Expression h1 = intersectedMultiSet.getHead();
                Expression h2 = otherMultiSet.getHead();
                Expression c1 = intersectedMultiSet.getCondition();
                Expression c2 = otherMultiSet.getCondition();
                Expression thereExists = ThereExists.make(i2, And.make(c2, Equality.make(h2, h1)));
                Context i1ExtendedContext = context.extendWith(i1);
                Expression thereExistsEvaluated = context.getTheory().evaluate(thereExists, i1ExtendedContext);
                if (thereExistsEvaluated.equals(false)) {
                    // They don't intersect, which means you have an empty
                    // set in the intersection, which means the whole thing
                    // results in the empty set.
                    resultIsEmptySet = true;
                } else if (!thereExistsEvaluated.equals(true)) {
                    // If we have a condition, other than false and true
                    // we will want to extend the current result by the condition
                    Expression extendedCondition = And.make(c1, thereExistsEvaluated);
                    intersectedMultiSet = (IntensionalSet) IntensionalSet.intensionalMultiSet(i1, h1, extendedCondition);
                    // Ensure we don't have a false condition.
                    Expression simplifiedIntersectedMultiSet = context.getTheory().evaluate(intersectedMultiSet, context);
                    if (Sets.isEmptySet(simplifiedIntersectedMultiSet)) {
                        resultIsEmptySet = true;
                    }
                }
            }
            if (resultIsEmptySet) {
                result = Sets.EMPTY_SET;
            } else if (nonIntensionalMultiSetArgs.size() > 0) {
                List<Expression> intersectedArgs = new ArrayList<>();
                intersectedArgs.add(intersectedMultiSet);
                intersectedArgs.addAll(nonIntensionalMultiSetArgs);
                result = Sets.makeIntersection(intersectedArgs.toArray(new Expression[intersectedArgs.size()]));
            } else {
                result = intersectedMultiSet;
            }
        }
    }
    return result;
}