public bool ChangeHeadOfRule(Grammar grammar)
{
for (var i = 0; i < NumberOfRetries; i++)
{
var rule = grammar.GetRandomRule();
if (!rule.IsInitialRule()) continue; //do not change complements of schematic rules. (push/pop)
if (rule.Production.Length > 1)
{
var newRule = new Rule(rule);
newRule.HeadPosition = (rule.HeadPosition + 1)%rule.Production.Length;
if (grammar.AreHeadRelationsConsistent(newRule))
{
grammar.DeleteRule(rule);
grammar.AddRule(newRule);
return true;
}
}
}
return false;
}
public bool DeleteRule(Grammar grammar)
{
var rule = grammar.GetRandomRule();
grammar.DeleteRule(rule);
return true;
}