Examples with SubExpressionsDepthFirstIterator com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator used on opensource projects

Example 6 with SubExpressionsDepthFirstIterator

use of com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator in project aic-expresso by aic-sri-international.

the class InversionSimplifier method applyInversion.

private static Expression applyInversion(Expression summationIndexedByFunction, Expression summationIndexFunctionName, FunctionType summationIndexFunctionType, List<Expression> originalQuantifierOrder, List<Expression> inversionQuantifierOrder, Context context) {
    Expression result;
    int indexOfSummationIndexedByFunction = inversionQuantifierOrder.indexOf(summationIndexedByFunction);
    // NOTE: only products will bubble up before the summation.
    List<Expression> productsBefore = inversionQuantifierOrder.subList(0, indexOfSummationIndexedByFunction);
    Expression lastQuantifierHead = getHead(originalQuantifierOrder.get(originalQuantifierOrder.size() - 1));
    Context innerContext = context;
    for (Expression quantifier : originalQuantifierOrder) {
        innerContext = innerContext.extendWith(getIndexExpressions(quantifier));
    }
    Context lastQuantifierHeadContext = innerContext;
    // TODO - remove temporary hack which collapses the function's argument domains
    // due to all the domain arguments being treated as constants. Instead should be using
    // set expression types on singletons.
    // Determine which domain arguments from the summation function can be collapsed
    List<Expression> productsBeforeIndices = new ArrayList<>();
    for (Expression productBefore : productsBefore) {
        productsBeforeIndices.add(getIndexAndType(productBefore).first);
    }
    Set<Integer> domainArgsToRemove = new HashSet<>();
    Set<Integer> domainArgsHaveVar = new HashSet<>();
    new SubExpressionsDepthFirstIterator(lastQuantifierHead).forEachRemaining(e -> {
        if (e.hasFunctor(summationIndexFunctionName)) {
            for (int i = 0; i < e.numberOfArguments(); i++) {
                if (lastQuantifierHeadContext.getTheory().isVariable(e.get(0), lastQuantifierHeadContext)) {
                    domainArgsHaveVar.add(i);
                }
                if (productsBeforeIndices.contains(e.get(i)) || Util.thereExists(new SubExpressionsDepthFirstIterator(e.get(i)), es -> productsBeforeIndices.contains(es))) {
                    domainArgsToRemove.add(i);
                }
            }
        }
    });
    // Remove arg positions that were not populated by a variable.
    for (int i = 0; i < summationIndexFunctionType.getArity(); i++) {
        if (!domainArgsHaveVar.contains(i)) {
            domainArgsToRemove.add(i);
        }
    }
    List<Expression> argTypes = new ArrayList<>();
    for (int i = 0; i < summationIndexFunctionType.getArity(); i++) {
        if (!domainArgsToRemove.contains(i)) {
            argTypes.add(parse(summationIndexFunctionType.getArgumentTypes().get(i).getName()));
        }
    }
    Expression codomainType = parse(summationIndexFunctionType.getCodomain().getName());
    Expression summationIndexReducedType;
    if (argTypes.size() == 0) {
        summationIndexReducedType = codomainType;
    } else {
        summationIndexReducedType = FunctionType.make(codomainType, argTypes);
    }
    Expression summationIndex = IndexExpressions.makeIndexExpression(summationIndexFunctionName, summationIndexReducedType);
    Expression phi = lastQuantifierHead.replaceAllOccurrences(e -> {
        Expression r = e;
        if (e.hasFunctor(summationIndexFunctionName)) {
            List<Expression> argsToKeep = new ArrayList<>();
            for (int i = 0; i < e.numberOfArguments(); i++) {
                if (!domainArgsToRemove.contains(i)) {
                    argsToKeep.add(e.get(i));
                }
            }
            if (argsToKeep.size() > 0) {
                r = Expressions.apply(summationIndexFunctionName, argsToKeep);
            } else {
                r = summationIndexFunctionName;
            }
        }
        return r;
    }, lastQuantifierHeadContext);
    Expression summationHead = phi;
    for (int i = indexOfSummationIndexedByFunction + 1; i < inversionQuantifierOrder.size(); i++) {
        Expression quantifier = inversionQuantifierOrder.get(i);
        Expression quantifierIntensionalSet = IntensionalSet.intensionalMultiSet(getIndexExpressions(quantifier), summationHead, getCondition(quantifier));
        summationHead = Expressions.apply(quantifier.getFunctor(), quantifierIntensionalSet);
    }
    Expression innerSummation = IntensionalSet.intensionalMultiSet(new ExtensionalIndexExpressionsSet(summationIndex), summationHead, getCondition(summationIndexedByFunction));
    result = Expressions.apply(FunctorConstants.SUM, innerSummation);
    for (int i = productsBefore.size() - 1; i >= 0; i--) {
        Expression product = productsBefore.get(i);
        product = IntensionalSet.intensionalMultiSet(getIndexExpressions(product), result, getCondition(product));
        result = Expressions.apply(FunctorConstants.PRODUCT, product);
    }
    return result;
}

Example 7 with SubExpressionsDepthFirstIterator

use of com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator in project aic-expresso by aic-sri-international.

the class FormulaUtil method getConstants.

/**
 * Extract the constants from the given formula. This is done by checking
 * the terms of any diseaulities or equalities in the formula as to whether
 * or not they are constants. These are the only locations constants should
 * exist in a formula.
 *
 * @param formula
 *            the formula constants are to be collected from.
 * @param context
 *            the current context, which is used to identify if a
 *            term is a constant.
 * @return the set of constants present in the given formula (may be empty).
 */
public static Set<Expression> getConstants(Expression formula, Context context) {
    Set<Expression> consts = new LinkedHashSet<Expression>();
    Iterator<Expression> subExpressionsIterator = new SubExpressionsDepthFirstIterator(formula);
    while (subExpressionsIterator.hasNext()) {
        Expression expression = subExpressionsIterator.next();
        if (Equality.isEquality(expression) || Disequality.isDisequality(expression)) {
            for (Expression term : expression.getArguments()) {
                if (context.isUniquelyNamedConstant(term)) {
                    consts.add(term);
                }
            }
        }
    }
    return consts;
}

Example 8 with SubExpressionsDepthFirstIterator

use of com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator in project aic-expresso by aic-sri-international.

the class AbstractSGVET method width.

private int width(Expression expression, Context context) {
    Set<Expression> variables = new LinkedHashSet<Expression>();
    Iterator<Expression> iterator = new SubExpressionsDepthFirstIterator(expression);
    while (iterator.hasNext()) {
        Expression subExpression = iterator.next();
        if (isVariable(subExpression, context)) {
            variables.add(subExpression);
        }
    }
    int result = variables.size();
    return result;
}

Example 9 with SubExpressionsDepthFirstIterator

use of com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator in project aic-expresso by aic-sri-international.

the class SGDPLLTTester method runModelCountingTestForSingleVariableConstraint.

private static void runModelCountingTestForSingleVariableConstraint(Expression variable, Collection<Expression> literals, Constraint constraint, boolean testAgainstBruteForce, Theory theory, Context context) {
    Expression literalsConjunction = And.make(literals);
    String problemDescription = "model counting of " + literalsConjunction + " for variable " + variable;
    output("Problem: " + problemDescription);
    Simplifier symbolicSolver = (e, p) -> computeModelCountBySolver((SingleVariableConstraint) e, p);
    SingleVariableConstraint singleVariableConstraint = (SingleVariableConstraint) constraint;
    Expression symbolicSolution = symbolicSolver.apply(singleVariableConstraint, context);
    if (Util.thereExists(new SubExpressionsDepthFirstIterator(symbolicSolution), e -> e instanceof QuantifiedExpression || Sets.isIntensionalSet(e))) {
        throw new Error("Symbolic solution is not quantifier-free: " + symbolicSolution);
    }
    output("Symbolic result: " + symbolicSolution);
    if (testAgainstBruteForce) {
        if (singleVariableConstraint.isContradiction()) {
            if (!symbolicSolution.equals(ZERO)) {
                throw new Error("Constraint is contradiction, but symbolic solver does not produce 0, but instead " + symbolicSolution);
            }
        } else {
            Expression testingVariable = singleVariableConstraint.getVariable();
            Set<Expression> allVariables = getVariableReferences(singleVariableConstraint, context);
            Collection<Expression> otherVariables = removeFromSetNonDestructively(allVariables, v -> v.equals(testingVariable));
            BinaryFunction<BruteForceCommonInterpreter, Context, Expression> fromInterpreterAndContextWithAssignmentToOtherVariablesToBruteForceSolution = (interpreter, contextWithAssignmentToOtherVariables) -> bruteForceModelCounterForVariableGivenInterpreterAndAssignmentToOtherVariables(variable, literalsConjunction, interpreter, theory, contextWithAssignmentToOtherVariables);
            testSymbolicVsBruteForceComputationForEachAssignment(theory, problemDescription, otherVariables, symbolicSolution, fromInterpreterAndContextWithAssignmentToOtherVariablesToBruteForceSolution, context);
        }
    } else {
        output("Skipping test againt brute-force.");
    }
}

Example 10 with SubExpressionsDepthFirstIterator

use of com.sri.ai.expresso.helper.SubExpressionsDepthFirstIterator in project aic-expresso by aic-sri-international.

the class InversionSimplifier method applyInversion.

private static Expression applyInversion(Expression summationIndexedByFunction, Expression summationIndexFunctionName, FunctionType summationIndexFunctionType, List<Expression> originalQuantifierOrder, List<Expression> inversionQuantifierOrder, Context context) {
    Expression result;
    int indexOfSummationIndexedByFunction = inversionQuantifierOrder.indexOf(summationIndexedByFunction);
    // NOTE: only products will bubble up before the summation.
    List<Expression> productsBefore = inversionQuantifierOrder.subList(0, indexOfSummationIndexedByFunction);
    Expression lastQuantifierHead = getHead(originalQuantifierOrder.get(originalQuantifierOrder.size() - 1));
    Context innerContext = context;
    for (Expression quantifier : originalQuantifierOrder) {
        innerContext = innerContext.extendWith(getIndexExpressions(quantifier));
    }
    Context lastQuantifierHeadContext = innerContext;
    // TODO - remove temporary hack which collapses the function's argument domains
    // due to all the domain arguments being treated as constants. Instead should be using
    // set expression types on singletons.				
    // Determine which domain arguments from the summation function can be collapsed
    List<Expression> productsBeforeIndices = new ArrayList<>();
    for (Expression productBefore : productsBefore) {
        productsBeforeIndices.add(getIndexAndType(productBefore).first);
    }
    Set<Integer> domainArgsToRemove = new HashSet<>();
    Set<Integer> domainArgsHaveVar = new HashSet<>();
    new SubExpressionsDepthFirstIterator(lastQuantifierHead).forEachRemaining(e -> {
        if (e.hasFunctor(summationIndexFunctionName)) {
            for (int i = 0; i < e.numberOfArguments(); i++) {
                if (lastQuantifierHeadContext.getTheory().isVariable(e.get(0), lastQuantifierHeadContext)) {
                    domainArgsHaveVar.add(i);
                }
                if (productsBeforeIndices.contains(e.get(i)) || Util.thereExists(new SubExpressionsDepthFirstIterator(e.get(i)), es -> productsBeforeIndices.contains(es))) {
                    domainArgsToRemove.add(i);
                }
            }
        }
    });
    // Remove arg positions that were not populated by a variable.
    for (int i = 0; i < summationIndexFunctionType.getArity(); i++) {
        if (!domainArgsHaveVar.contains(i)) {
            domainArgsToRemove.add(i);
        }
    }
    List<Expression> argTypes = new ArrayList<>();
    for (int i = 0; i < summationIndexFunctionType.getArity(); i++) {
        if (!domainArgsToRemove.contains(i)) {
            argTypes.add(parse(summationIndexFunctionType.getArgumentTypes().get(i).getName()));
        }
    }
    Expression codomainType = parse(summationIndexFunctionType.getCodomain().getName());
    Expression summationIndexReducedType;
    if (argTypes.size() == 0) {
        summationIndexReducedType = codomainType;
    } else {
        summationIndexReducedType = FunctionType.make(codomainType, argTypes);
    }
    Expression summationIndex = IndexExpressions.makeIndexExpression(summationIndexFunctionName, summationIndexReducedType);
    Expression phi = lastQuantifierHead.replaceAllOccurrences(e -> {
        Expression r = e;
        if (e.hasFunctor(summationIndexFunctionName)) {
            List<Expression> argsToKeep = new ArrayList<>();
            for (int i = 0; i < e.numberOfArguments(); i++) {
                if (!domainArgsToRemove.contains(i)) {
                    argsToKeep.add(e.get(i));
                }
            }
            if (argsToKeep.size() > 0) {
                r = Expressions.apply(summationIndexFunctionName, argsToKeep);
            } else {
                r = summationIndexFunctionName;
            }
        }
        return r;
    }, lastQuantifierHeadContext);
    Expression summationHead = phi;
    for (int i = indexOfSummationIndexedByFunction + 1; i < inversionQuantifierOrder.size(); i++) {
        Expression quantifier = inversionQuantifierOrder.get(i);
        Expression quantifierIntensionalSet = IntensionalSet.intensionalMultiSet(getIndexExpressions(quantifier), summationHead, getCondition(quantifier));
        summationHead = Expressions.apply(quantifier.getFunctor(), quantifierIntensionalSet);
    }
    Expression innerSummation = IntensionalSet.intensionalMultiSet(new ExtensionalIndexExpressionsSet(summationIndex), summationHead, getCondition(summationIndexedByFunction));
    result = Expressions.apply(FunctorConstants.SUM, innerSummation);
    for (int i = productsBefore.size() - 1; i >= 0; i--) {
        Expression product = productsBefore.get(i);
        product = IntensionalSet.intensionalMultiSet(getIndexExpressions(product), result, getCondition(product));
        result = Expressions.apply(FunctorConstants.PRODUCT, product);
    }
    return result;
}