public void AddClause(IClause clause)
{
if (clause == null)
{
return;
}
_satisfiedLiterals.Clear();
if (clause.Head != null && clause.Head.Negated && clause.Body.Count > 0)
{
var newClause = new Clause(new Literal(clause.Head.NegatedValue()));
foreach (var literal in clause.Body)
{
newClause.Body.Add(new Literal(literal.NegatedValue()));
}
AddClause(newClause);
return;
}
var headNode = clause.Head != null ? (_graph.GetNode(clause.Head.Value) ?? _graph.AddNode(clause.Head.Negated ? (ILogicNode) new ClauseNode(clause.Head.Value) : new LiteralNode(clause.Head.Value)).GetNode(clause.Head.Value)) : null;
if (clause.Body.Count < 1)
{
if (headNode == null)
{
throw new NullReferenceException("Clause Head is null");
}
headNode.Fact = true;
}
else if (clause.Body.Count == 1)
{
if (clause.Head == null)
{
throw new NullReferenceException("Clause Head is null");
}
var literal = clause.Body.First();
if (clause.Head.Value != literal.Value)
{
var node = _graph.GetNode(literal.Value) ?? _graph.AddNode(literal.Negated ? (ILogicNode) new ClauseNode(literal.Value) : new LiteralNode(literal.Value)).GetNode(literal.Value);
if (_graph.GetEdge(headNode, node) == null)
{
_graph.AddEdge(new DirectedEdge <ILogicNode> (headNode, node));
}
}
}
else if (clause.Body.Count > 1)
{
if (clause.Head != null)
{
var literals = clause.Body.Where(literal => clause.Head.Value != literal.Value).ToList();
if (literals.Count > 0)
{
var clauseKey = ClauseKey(literals);
var clauseNode = _graph.GetNode(clauseKey) ?? _graph.AddNode(new ClauseNode(clauseKey)).GetNode(clauseKey);
if (_graph.GetEdge(headNode, clauseNode) == null)
{
_graph.AddEdge(new DirectedEdge <ILogicNode> (headNode, clauseNode));
}
foreach (var literalNode in literals.Select(literal => _graph.GetNode(literal.Value) ?? _graph.AddNode(literal.Negated ? (ILogicNode) new ClauseNode(literal.Value) : new LiteralNode(literal.Value)).GetNode(literal.Value)).Where(literalNode => _graph.GetEdge(clauseNode, literalNode) == null))
{
_graph.AddEdge(new WeightedDirectedEdge <ILogicNode> (clauseNode, literalNode, 1));
}
}
}
else
{
var disjointLiteralKey = DisjointLiteralKey(clause.Body);
var disjointLiteral = _graph.GetNode(disjointLiteralKey) ?? _graph.AddNode(new LiteralNode(disjointLiteralKey)).GetNode(disjointLiteralKey);
foreach (var literalNode in clause.Body.Select(literal => _graph.GetNode(literal.Value) ?? _graph.AddNode(literal.Negated ? (ILogicNode) new ClauseNode(literal.Value) : new LiteralNode(literal.Value)).GetNode(literal.Value)).Where(literalNode => _graph.GetEdge(disjointLiteral, literalNode) == null))
{
_graph.AddEdge(new DirectedEdge <ILogicNode>(disjointLiteral, literalNode));
}
}
}
var negated = clause.Head != null ? new Clause(new Literal(clause.Head.NegatedValue())) : new Clause();
foreach (var dependency in clause.Body)
{
negated.Body.Add(new Literal(dependency.NegatedValue()));
}
AddNegatedClause(negated);
if (headNode != null && negated.Head != null)
{
var negatedHeadNode = _graph.GetNode(negated.Head.Value);
if (negatedHeadNode != null)
{
if (headNode.Fact && negatedHeadNode.Fact)
{
throw new Exception("KB is inconsistent, " + headNode.Id + " and " + negatedHeadNode.Id + " are both facts!");
}
if (clause.Body.Count > 0)
{
var nodesA = clause.Body.Select(literal => _graph.GetNode(literal.Value));
var nodesB = clause.Body.Select(literal => _graph.GetNode(literal.NegatedValue()));
if (SharedAncestor(nodesA, nodesB))
{
Console.WriteLine("Adding " + clause.ToProperString() + " will cause conflict skipping clause...");
RemoveClause(clause);
}
}
}
}
if (headNode != null && headNode.Fact)
{
FactFlow(headNode);
}
if (clause.Body.Count > 0)
{
foreach (var node in clause.Body.Select(literal => _graph.GetNode(literal.Value)).Where(node => node.Fact))
{
FactFlow(node);
}
foreach (var node in clause.Body.Select(literal => _graph.GetNode(literal.NegatedValue())).Where(node => node.Fact))
{
FactFlow(node);
}
}
}