/// <summary>
/// Applies the Resolution technic.
/// </summary>
/// <param name="other">other disjunction to apply.</param>
/// <returns>the resoluted disjunction if found</returns>
public MultipleDisjunction ApplyResolution(MultipleDisjunction other)
{
List <Proposition> result = new List <Proposition>(m_props);
result.AddRange(other.m_props);
foreach (Proposition p in m_props)
{
foreach (Proposition q in other.m_props)
{
if (p.Negated().Equals(q) || q.Negated().Equals(p))
{
result.Remove(p);
result.Remove(q);
MultipleDisjunction md = new MultipleDisjunction(result);
md.Simplify();
return(md);
}
}
}
return(null); // A resolution wasn't found.
}
public bool ProveIt(ReportDelegate report)
{
// Negates the theorem.
AST negated = CNF.Convert(Theorem.Ast.Negation());
m_theoremNegation = new CNFProposition(negated);
report(string.Format(
"Teorema: {0}\nTeorema negado: {1}\nTeorema negado em FNC: {2}\n",
CNF.Convert(Theorem.Ast).ToString(),
negated.ToString(),
m_theoremNegation.ToString()
));
// Join all premisses and sort them.
List <MultipleDisjunction> clauses = new List <MultipleDisjunction>();
foreach (CNFProposition premisse in Premisses.Values)
{
clauses.AddRange(premisse.Props);
}
clauses.AddRange(m_theoremNegation.Props);
clauses.Sort();
string premissesStr = "Cláusulas (premissas + negação do teorema):";
int premisseCount = 0;
foreach (MultipleDisjunction premisse in clauses)
{
premissesStr += string.Format("\n({0}) {1}", ++premisseCount, premisse);
}
report(premissesStr + "\n");
// Evaluate Resolutions.
report("\n=====================\nTentando provar...\n------------------\n\n");
List <TestedPair> tested = new List <TestedPair>();
bool solved = false;
for (int i = 0; i < clauses.Count; i++)
{
for (int j = 0; j < clauses.Count; j++)
{
if (i == j)
{
continue;
}
TestedPair pair = new TestedPair(i, j);
if (tested.Contains(pair))
{
continue;
}
else
{
tested.Add(pair);
}
MultipleDisjunction resolvent = clauses[i].ApplyResolution(clauses[j]);
if (resolvent == null)
{
continue; // complementaries not found.
}
solved = resolvent.ISNullClause;
if (solved)
{
report(string.Format(
"Cláusula nula encontrada da aplicação de {0} em {1}.\n",
j + 1, i + 1
));
break;
}
if (clauses.Contains(resolvent))
{
continue;
}
clauses.Add(resolvent);
report(string.Format(
"({0}) {1} :: De {2} em {3}.\n",
clauses.Count,
resolvent.ToString(),
j + 1, i + 1
));
i = j = 0;
}
if (solved)
{
break;
}
}
report("\n\n==================\n");
report(solved ? "TEOREMA PROVADO!" : "NÃO FOI POSSÍVEL PROVAR A TEORIA!");
report("\n==================\n\n");
return(solved);
}