/// <summary>
/// Generate up to k random witnesses accepted by the PDA. If the language is empty
/// then the enumeration is empty. If k is 0 or negative then the enumeration is unbounded.
/// Repetitions may occur.
/// </summary>
public IEnumerable <T[]> GenerateWitnesses(int k = 0)
{
if (this.automaton.IsEmpty)
{
yield break;
}
else
{
var ra = new ReachabilityAutomaton(this, false);
foreach (var witness in ra.GenerateWitnesses(k))
{
yield return(witness.ToArray());
}
}
}
bool IsNonempty_helper(out T[] witness, bool canonical)
{
if (this.automaton.IsEmpty)
{
witness = null;
return(false);
}
else
{
var ra = new ReachabilityAutomaton(this, canonical);
var witness1 = ra.GetWitness();
if (witness1 == null)
{
witness = null;
return(false);
}
else
{
witness = witness1.ToArray();
return(true);
}
}
}