I have the following method:

static bool ForwardChaining(List<Clause> clauses, string goal)
        {
            Queue<string> agenda = new Queue<string>();
            Dictionary<string, bool> inferred = new Dictionary<string, bool>();
            Dictionary<Clause, long> count = new Dictionary<Clause, long>();


            foreach (Clause clause in clauses)
            {
                count.Add(clause, clause.Premises.Count);
                if (!inferred.ContainsKey(clause.Conclusion))
                    inferred.Add(clause.Conclusion, false);
                foreach (string symbol in clause.Premises )
                {
                    if (!inferred.ContainsKey(symbol))
                        inferred.Add(symbol, false);
                }
            }           

            agenda.Enqueue("true");
            if(!inferred.ContainsKey("true"))
                inferred.Add("true", true);

            while (agenda.Count > 0)
            {
                string p = agenda.Dequeue();

                if (p == goal)
                {
                    return true;
                }

                if (inferred[p] == false)
                {
                    inferred[p] = true;
                    foreach (Clause clause in clauses)
                    {
                        if (clause.Premises.Contains(p))
                        {
                            if (count[clause] > 0)
                            {
                                count[clause]--;
                                if (count[clause] == 0)
                                {
                                    agenda.Enqueue(clause.Conclusion);
                                }
                            }
                        }
                    }
                }
            }

            return false;
        }

It should be capable of determining if a given goal, follows logically from a list of definite clauses by returning true of it does. The class Clauses that I made has a Conclusion variable and a list of premises. I think it should work but somehow in some testcases it fails.

I googled how to implement forward chaining in C# and tried to apply it. But I cannot find the mistake in my work.