// Start the Front-Chain process
public override bool Algorithm()
{
while (Agenda.Count != 0)
{
// Pop the first element at agenda and temporarily store it at p
string p = Agenda[0];
Entailed.Add(p);
Agenda.RemoveAt(0);
for (int i = 0; i < Clauses.Count; i++)
{
if (Contains(Clauses[i], p))
{
//Decrement Count at i and checks if zero
if ((--Count[i]) == 0)
{
// Get the Conclusion
string head = Regex.Split(Clauses[i], "=>")[1];
// Check if reach ask
if (head.Equals(Ask))
{
return(true);
}
Agenda.Add(head);
}
}
}
}
// Cannot be entailed
return(false);
}
public bool BCentails()
{
while (Agenda.Count > 0)
{
// take the first item and process it
string q = Agenda[Agenda.Count - 1];
Agenda.RemoveAt(Agenda.Count - 1);
if (q != Ask)
{
if (!Entailed.Contains(q))
{
Entailed.Insert(0, q);
}
}
if (!(Facts.Contains(q)))
{
List <string> prem = new List <string>();
// for each of the clauses...
for (int i = 0; i < Clauses.Count; i++)
{
// .... that contain p in its premise
if (ClauseContains(Clauses[i], q, 1))
{
List <string> temp = GetPremises(Clauses[i]);
for (int j = 0; j < temp.Count; j++)
{
prem.Add(temp[j]);
}
}
}
if (prem.Count == 0)
{
return(false);
}
else
{
for (int i = 0; i < prem.Count; i++)
{
if (!Entailed.Contains(prem[i]))
{
Agenda.Add(prem[i]);
}
}
}
}
}
// while end
return(true);
}
// FC algorithm
public bool FCentails()
{
// loop through while there are unprocessed facts
while (Agenda.Count > 0)
{
// take the first item and process it
string p = Agenda[0];
Agenda.RemoveAt(0);
// add to entailed :: List of symbols already processed
Entailed.Add(p);
if (p == Ask)
{
return(true);
}
// for each of the clauses...
for (int i = 0; i < Clauses.Count; i++)
{
// .... that contain p in its premise
if (ClauseContains(Clauses[i], p, 0))
{
// reduce count : unknown elements in each premise
int j = Count[i];
Count[i] = --j;
// all the elements in the premise are now known
if (Count[i] == 0)
{
string[] separatingChars = { "=>" };
string head = Clauses[i].Split(separatingChars, System.StringSplitOptions.RemoveEmptyEntries)[1];
if (head.Equals(Ask))
{
return(true);
}
if (!Entailed.Contains(head))
{
Agenda.Add(head);
}
}
}
}
}
// if we arrive here then ask cannot entailed
return(false);
}
