private bool AreDistinguishable(ThreeAutomaton <S> fa, Equivalence E, Tuple <int, int> pq, IBooleanAlgebraPositive <S> solver)
{
foreach (Move <S> from_p in fa.GetMovesFrom(pq.Item1))
{
foreach (Move <S> from_q in fa.GetMovesFrom(pq.Item2))
{
if (from_p.TargetState != from_q.TargetState &&
!E.AreEquiv(from_p.TargetState, from_q.TargetState))
{
if (solver.IsSatisfiable(solver.MkAnd(from_p.Label, from_q.Label)))
{
return(true);
}
}
}
}
return(false);
}
/// <summary>
/// Checks that for all states q, if q has two or more outgoing
/// moves then the conditions of the moves are pairwise disjoint, i.e.,
/// their conjunction is unsatisfiable.
/// If the check succeeds, sets IsDeterministic to true.
/// Throws AutomataException if the FSA is not epsilon-free.
/// </summary>
/// <param name="solver">used to make conjunctions and to check satisfiability of resulting conditions</param>
public void CheckDeterminism(IBooleanAlgebraPositive <S> solver, bool resetIsDeterministicToFalse = false)
{
if (resetIsDeterministicToFalse)
{
isDeterministic = false;
}
if (isDeterministic) //already known to be deterministic
{
return;
}
foreach (int state in States)
{
//Normal Moves
var moves = delta[state];
int k = moves.Count;
if (k > 1)
{
S sofar = moves[0].action.guard;
for (int i = 1; i < k; i++)
{
var sofar_and_i = solver.MkAnd(sofar, moves[i].action.guard);
if (solver.IsSatisfiable(sofar_and_i))
{
isDeterministic = false;
return; //nondeterministic
}
if (i < k - 1)
{
sofar = solver.MkOr(sofar, moves[i].action.guard);
}
}
}
//Final moves
var finmoves = deltaFinal[state];
k = finmoves.Count;
if (k > 1)
{
S sofar = finmoves[0].action.guard;
for (int i = 1; i < k; i++)
{
var sofar_and_i = solver.MkAnd(sofar, finmoves[i].action.guard);
if (solver.IsSatisfiable(sofar_and_i))
{
isDeterministic = false;
return; //nondeterministic
}
if (i < k - 1)
{
sofar = solver.MkOr(sofar, finmoves[i].action.guard);
}
}
}
//Fin vs nonfin
foreach (var move in delta[state])
{
foreach (var finalMove in deltaFinal[state])
{
if (move.action.lookahead <= finalMove.action.lookahead) //Move does not have longer lookahead than fin move
{
if (solver.IsSatisfiable(solver.MkAnd(move.action.guard, finalMove.action.guard)))
{
isDeterministic = false;
return; //nondeterministic
}
}
}
}
}
isDeterministic = true; //deterministic
}