AIMA.Core.Logic.Propositional.Algorithms.PLResolution.filterOutClausesWithTwoComplementaryLiterals C# (CSharp) Method

        private List<Sentence> filterOutClausesWithTwoComplementaryLiterals(
                List<Sentence> clauses)
        {
            List<Sentence> filtered = new List<Sentence>();
            SymbolClassifier classifier = new SymbolClassifier();
            foreach(Sentence clause in clauses)
            {

                List<Symbol> positiveSymbols = classifier
                        .getPositiveSymbolsIn(clause);
                List<Symbol> negativeSymbols = classifier
                        .getNegativeSymbolsIn(clause);
                if ((SetOps.intersection(positiveSymbols, negativeSymbols).Count == 0))
                {
                    filtered.Add(clause);
                }
            }
            return filtered;
        }