public LogicForm()
{
InitializeComponent();
logicApp = new LogicApp(new Parser());
semanticTableauxApp = new SemanticTableauxApp(new Parser());
propositionGenerator = new PropositionGenerator();
}
public Proposition CreateDisjunctiveNormalForm()
{
List <Proposition> propositionList = GenerateDisjunctiveNormalFormEquivalentPropositions();
// Check for missing variables.
HashSet <Proposition> missingVariables = GetMissingVariables(propositionList);
if (missingVariables.Count == propositionVariablesSet.Count)
{
if (propositionList.Count > 0)
{
Proposition p = propositionList[0];
propositionList.Remove(p);
if (p.GetType() == typeof(True))
{
// Create tautologies.
foreach (Proposition variable in missingVariables)
{
propositionList.Add(PropositionGenerator.CreateTautologyFromProposition(variable));
}
}
}
else
{
// Create contradictions.
foreach (Proposition variable in missingVariables)
{
propositionList.Add(PropositionGenerator.CreateContradictionFromProposition(variable));
}
}
}
// If we miss one or more variables but not all, this indicates that those variables
// had no meaning in the original expression. Thus by logical equivalence we can say that
// the expression would be equivalent to for ex: A & (B | ~(B)), the truth value of B
// does not matter thus we can restate this as A | 0 which means we are totally reliant
// on the truth value of A which can be obtained by creating a contradiction of
// the variable that does not matter (B) in this case to keep the result column of equal
// length, this would result in A | (B & ~(B)) which IS in DNF
if (missingVariables.Count > 0 && missingVariables.Count < propositionVariablesSet.Count)
{
foreach (Proposition missingVariable in missingVariables)
{
propositionList.Add(PropositionGenerator.CreateContradictionFromProposition(missingVariable));
}
}
propositionList = CreateCorrespondingDisjuncts(propositionList);
return(propositionList[0]);
}