private bool IS_TRUE(LogicalExpression expression, Dictionary <string, bool> model)
{
bool result = true;
if (expression.Symbol != null)
{
result = IS_TRUE(expression.Symbol, model);
}
else
{
if (expression.Connective == "&")
{
foreach (LogicalExpression child in expression.Children)
{
result = result && IS_TRUE(child, model);
}
}
if (expression.Connective == "\\/")
{
result = false;
foreach (LogicalExpression child in expression.Children)
{
result = result || IS_TRUE(child, model);
}
}
if (expression.Connective == "=>")
{
if (IS_TRUE(expression.Children[0], model) && !IS_TRUE(expression.Children[1], model))
{
result = false;
}
else
{
result = true;
}
}
if (expression.Connective == "<=>")
{
if (IS_TRUE(expression.Children[0], model) == IS_TRUE(expression.Children[1], model))
{
result = true;
}
else
{
result = false;
}
}
}
return(result);
}
public LogicalExpression ConvertToCNF(LogicalExpression expression)
{
if (expression.Symbol != null)
{
return(expression);
}
else if (expression.Connective == "<=>")
{
LogicalExpression newExpression = new LogicalExpression();
newExpression.Connective = "&";
LogicalExpression child1 = new LogicalExpression(expression.Children[0].OriginalString);
LogicalExpression child2 = new LogicalExpression(expression.Children[1].OriginalString);
List <LogicalExpression> children = new List <LogicalExpression>();
children.Add(child1);
children.Add(child2);
newExpression.Children = children;
Console.WriteLine("Remove Bi-Implication: ");
newExpression.printInfo();
return(newExpression);
}
else if (expression.Connective == "=>")
{
LogicalExpression newExpression = new LogicalExpression();
newExpression.Connective = "\\/";
LogicalExpression child1 = ConvertToCNF(expression.Children[0]);
LogicalExpression child2 = ConvertToCNF(expression.Children[1]);
LogicalExpression negateChild1 = new LogicalExpression();
negateChild1.Connective = "~";
negateChild1.Children.Add(child1);
newExpression.Children.Add(negateChild1);
newExpression.Children.Add(child2);
Console.WriteLine("Remove Implication: ");
newExpression.printInfo();
return(newExpression);
}
else if (expression.Connective == "~")
{
if (expression.Children[0].Symbol != null)
{
return(expression);
}
else
{
if (expression.Children[0].Connective == "\\/")
{
LogicalExpression newExpression = new LogicalExpression();
newExpression.Connective = "&";
LogicalExpression child1 = new LogicalExpression();
child1.Connective = "~";
child1.Children.Add(expression.Children[0].Children[0]);
LogicalExpression child2 = new LogicalExpression();
child2.Connective = "~";
child2.Children.Add(expression.Children[0].Children[1]);
newExpression.Children.Add(child1);
newExpression.Children.Add(child2);
return(newExpression);
}
else if (expression.Children[0].Connective == "&")
{
LogicalExpression newExpression = new LogicalExpression();
newExpression.Connective = "\\/";
LogicalExpression child1 = new LogicalExpression();
child1.Connective = "~";
child1.Children.Add(expression.Children[0].Children[0]);
LogicalExpression child2 = new LogicalExpression();
child2.Connective = "~";
child2.Children.Add(expression.Children[0].Children[1]);
newExpression.Children.Add(child1);
newExpression.Children.Add(child2);
return(newExpression);
}
}
}
return(expression);
}
public void SentenceParser(string sentence)
{
int bracketCounter = 0;
int operatorIndex = -1;
bool trigger = true;
bool trigger2 = true;
sentence.Trim();
Console.WriteLine("Initial Sentence: " + sentence);
//Console.Write("OperatorIndex: "+ operatorIndex + "\n");
for (int i = 0; i < sentence.Length; i++)
{
char c = sentence.ElementAt(i);
if (c == '(')
{
//Console.WriteLine(bracketCounter);
bracketCounter = bracketCounter + 1;
}
else if (c == ')')
{
bracketCounter--;
//Console.WriteLine(bracketCounter);
}
else if ((c == '<') && bracketCounter == 0)
{
//Console.WriteLine("bracketCounter should be 0: " + bracketCounter);
operatorIndex = i;
trigger = false;
trigger2 = false;
}
else if ((c == '=' && c + 1 == '>') && bracketCounter == 0 && trigger2)
{
operatorIndex = i;
trigger = false;
trigger2 = false;
}
else if ((c == '&') && bracketCounter == 0 && trigger && trigger2)
{
operatorIndex = i;
trigger = false;
trigger2 = false;
}
else if (c == '\\' && bracketCounter == 0 && trigger && trigger2)
{
operatorIndex = i;
trigger = false;
trigger2 = false;
}
else if (c == '~' && bracketCounter == 0 && operatorIndex < 0 && trigger && trigger2)
{
operatorIndex = i;
}
}
//Console.WriteLine("op: " +operatorIndex);
if (operatorIndex < 0)
{
sentence = sentence.Trim();
if (sentence.ElementAt(0) == '(' && sentence.ElementAt(sentence.Length - 1) == ')')
{
SentenceParser(sentence.Substring(1, sentence.Length - 2));
}
}
else
{
//Console.WriteLine("Entering Else");
//Console.WriteLine(sentence);
if (sentence.ElementAt(operatorIndex) == '<')
{
Console.WriteLine("sentence: " + sentence);
string first = sentence.Substring(0, operatorIndex);
string second = sentence.Substring(operatorIndex + 3);
first = first.Trim();
second = second.Trim();
LogicalExpression child1 = new LogicalExpression(first);
LogicalExpression child2 = new LogicalExpression(second);
_children.Add(child1);
_children.Add(child2);
_connective = "<=>";
}
else if (sentence.ElementAt(operatorIndex) == '=')
{
string first = sentence.Substring(0, operatorIndex);
string second = sentence.Substring(operatorIndex + 2);
first = first.Trim();
second = second.Trim();
LogicalExpression child1 = new LogicalExpression(first);
LogicalExpression child2 = new LogicalExpression(second);
_children.Add(child1);
_children.Add(child2);
_connective = "=>";
}
else if (sentence.ElementAt(operatorIndex) == '&')
{
string first = sentence.Substring(0, operatorIndex);
string second = sentence.Substring(operatorIndex + 1);
first = first.Trim();
second = second.Trim();
LogicalExpression child1 = new LogicalExpression(first);
LogicalExpression child2 = new LogicalExpression(second);
_children.Add(child1);
_children.Add(child2);
_connective = "&";
}
else if (sentence.ElementAt(operatorIndex) == '\\')
{
string first = sentence.Substring(0, operatorIndex);
string second = sentence.Substring(operatorIndex + 2);
first = first.Trim();
second = second.Trim();
LogicalExpression child1 = new LogicalExpression(first);
LogicalExpression child2 = new LogicalExpression(second);
_children.Add(child1);
_children.Add(child2);
_connective = "\\/";
}
else if (sentence.ElementAt(operatorIndex) == '~')
{
string first = sentence.Substring(operatorIndex + 1);
first = first.Trim();
LogicalExpression child = new LogicalExpression(first);
_children.Add(child);
_connective = "~";
}
//else
//{
// _symbol = sentence;
// _connective = null;
// _children = null;
//}
}
}
/*
* Reads Problem File
* @Param filename - string that gives name of file to read from
* @Param solver - string that tells reader what type of engine is being used. Changes
* output if more advanced algorithms used.
*/
public static bool ReadProblem(string filename, string solver)
{
List <string> text = new List <string>();
//tries to read problem file, if it can't returns false
try
{
StreamReader reader = File.OpenText(filename);
for (int i = 0; i < 4; i++)
{
text.Add(reader.ReadLine());
}
reader.Close();
}
catch
{
Console.WriteLine("Error: Could not read file");
return(false);
}
string[] knowledge = text[1].Split(';');
knowledge = knowledge.Take(knowledge.Count() - 1).ToArray();
List <Clause> clauses = new List <Clause>();
// If basic checking method
if (solver != "GTT" || solver != "DPLL")
{
foreach (string s in knowledge)
{
if (s.Contains("=>"))
{
List <string> premiseSymbols = new List <string>();
int index = s.IndexOf("=>");
string premise = s.Substring(0, index);
string conclusion = s.Substring(index + 2);
conclusion = conclusion.Trim();
string[] splitPremise = { "" };
if (premise.Contains("&"))
{
splitPremise = premise.Split('&');
}
else
{
splitPremise[0] = premise;
}
foreach (string symbol in splitPremise)
{
string trim = symbol.Trim();
premiseSymbols.Add(trim);
}
clauses.Add(new Clause(premiseSymbols, conclusion));
}
else
{
string conclusion = s.Trim();
clauses.Add(new Clause(conclusion));
}
}
_query = text[3];
_kb = new KnowledgeBase(clauses);
return(true);
}
// if solving method more advanced clauses
else
{
List <LogicalExpression> kb = new List <LogicalExpression>();
foreach (string s in knowledge)
{
LogicalExpression exp = new LogicalExpression(s);
//exp.printInfo();
kb.Add(exp);
}
_akb = new AdvancedKnowledgeBase(kb);
_query = text[3];
return(true);
}
}
