/* Generate the transition relation R */
private FormulaNode GenTransition(SymbolicState from, SymbolicState to)
{
List <FormulaNode> terms = new List <FormulaNode>();
foreach (var e in elementary)
{
if (e.GetLogicOperator() != LogicOperator.EX)
{
continue;
}
// if e = EX(g), generate the term "e(from) | ~g(to)"
FormulaNode body = e[0]; // the formula inside the EX
FormulaNode notBody = CTLUtils.nnfNegate(body);
FormulaNode left = from.ValueOf(e);
FormulaNode right = to.ValueOf(notBody);
terms.Add(new FormulaNode(LogicOperator.OR, left, right));
}
return(JoinTerms(LogicOperator.AND, terms));
}
public bool Check()
{
SymbolicState v = new SymbolicState(elementary, "v");
// initially, all possible states belong to the structure
FormulaNode states = new FormulaNode(FormulaNode.TRUE_LITERAL);
FormulaNode oldStates;
while (true)
{
iterations++;
#if DEBUG
Console.WriteLine("Iteration " + iterations.ToString());
#endif
oldStates = states;
FormulaNode succ = GenSucc(states, v);
FormulaNode lc1 = GenLC1(states, v);
FormulaNode e = GenE(states, v);
FormulaNode a = GenA(states, v);
states = new FormulaNode(LogicOperator.AND, states, succ);
states = new FormulaNode(LogicOperator.AND, states, lc1);
states = new FormulaNode(LogicOperator.AND, states, e);
states = new FormulaNode(LogicOperator.AND, states, a);
if (IsFixpoint(oldStates, states, v))
{
break;
}
}
#if DEBUG
Console.WriteLine("Reached fixpoint. Checking for satisfying state");
#endif
FormulaNode formulaValue = v.ValueOf(normalized);
FormulaNode formulaAndValid = new FormulaNode(LogicOperator.AND, states, formulaValue);
FormulaNode sat = v.Quantify(LogicOperator.EXISTS, formulaAndValid);
return(FormulaCNF.QBFSAT(sat));
}
