/// <summary>
/// Get all states in the given finite automaton from which no accepting state is reachable.
/// </summary>
/// <param name="fa">given finite automaton</param>
/// <returns>all dead states in the finite automaton</returns>
public static Set <Term> GetDeadStates(FSM fa)
{
//build a graph from fa
Dictionary <Term, int> stateToVertexMap = new Dictionary <Term, int>();
stateToVertexMap[fa.InitialState] = 0;
int i = 1;
foreach (Term state in fa.States.Remove(fa.InitialState))
{
stateToVertexMap[state] = i++;
}
//create edges that correspond to the transitions
GraphTraversals.Edge[] edges = new GraphTraversals.Edge[fa.Transitions.Count];
Triple <Term, CompoundTerm, Term>[] transitions = new Triple <Term, CompoundTerm, Term> [fa.Transitions.Count];
i = 0;
foreach (Triple <Term, CompoundTerm, Term> trans in fa.Transitions)
{
edges[i] = new GraphTraversals.Edge(stateToVertexMap[trans.First],
stateToVertexMap[trans.Third], i);
transitions[i++] = trans;
}
GraphTraversals.Graph g =
new GraphTraversals.Graph(0, edges, new GraphTraversals.Edge[] { },
GraphTraversals.WeakClosureEnum.DoNotClose);
int[] acceptingVertices = new int[fa.AcceptingStates.Count];
i = 0;
foreach (Term accState in fa.AcceptingStates)
{
acceptingVertices[i++] = stateToVertexMap[accState];
}
GraphTraversals.HSet deadVertices = g.DeadStates(acceptingVertices);
return(fa.States.Select(delegate(Term state)
{ return deadVertices.Contains(stateToVertexMap[state]); }));
}
/// <summary>
/// Get all states in the given finite automaton from which no accepting state is reachable.
/// </summary>
/// <param name="fa">given finite automaton</param>
/// <returns>all dead states in the finite automaton</returns>
public static Set<Term> GetDeadStates(FSM fa)
{
//build a graph from fa
Dictionary<Term, int> stateToVertexMap = new Dictionary<Term, int>();
stateToVertexMap[fa.InitialState] = 0;
int i = 1;
foreach (Term state in fa.States.Remove(fa.InitialState))
stateToVertexMap[state] = i++;
//create edges that correspond to the transitions
GraphTraversals.Edge[] edges = new GraphTraversals.Edge[fa.Transitions.Count];
Triple<Term, CompoundTerm, Term>[] transitions = new Triple<Term, CompoundTerm, Term>[fa.Transitions.Count];
i = 0;
foreach (Triple<Term, CompoundTerm, Term> trans in fa.Transitions)
{
edges[i] = new GraphTraversals.Edge(stateToVertexMap[trans.First],
stateToVertexMap[trans.Third], i);
transitions[i++] = trans;
}
GraphTraversals.Graph g =
new GraphTraversals.Graph(0, edges, new GraphTraversals.Edge[] { },
GraphTraversals.WeakClosureEnum.DoNotClose);
int[] acceptingVertices = new int[fa.AcceptingStates.Count];
i = 0;
foreach (Term accState in fa.AcceptingStates)
acceptingVertices[i++] = stateToVertexMap[accState];
GraphTraversals.HSet deadVertices = g.DeadStates(acceptingVertices);
return fa.States.Select(delegate(Term state)
{ return deadVertices.Contains(stateToVertexMap[state]); });
}
