private void RemoveClause(IClause clause)
{
var headNode = clause.Head != null?_graph.GetNode(clause.Head.Value) : null;
if (headNode != null)
{
if (clause.Body.Count == 1)
{
var literalNode = _graph.GetNode(clause.Body.First().Value);
var edge = _graph.GetEdge(headNode, literalNode);
_graph.RemoveEdge(edge);
headNode = _graph.GetNode(clause.Head.NegatedValue());
literalNode = _graph.GetNode(clause.Body.First().NegatedValue());
edge = _graph.GetEdge(headNode, literalNode);
_graph.RemoveEdge(edge);
}
else if (clause.Body.Count > 1)
{
var clauseNode = _graph.GetNode(ClauseKey(clause.Body));
var edge = _graph.GetEdge(headNode, clauseNode);
_graph.RemoveEdge(edge);
if (_graph.InDegree(clauseNode) < 1)
{
_graph.RemoveNode(clauseNode);
}
headNode = _graph.GetNode(clause.Head.NegatedValue());
foreach (var literalNode in clause.Body.Select(dependency => _graph.GetNode(dependency.NegatedValue())))
{
edge = _graph.GetEdge(headNode, literalNode);
_graph.RemoveEdge(edge);
}
}
}
}