Returns the child label index from the (unary) rule index
Gives all binary rule indices with this left child
Gives all binary rule indices with this parent
Gives all binary rule indices with this right child
Gives all unary rule indices with this child
Gives all unary rule indices with this parent
Returns the left child label index from the rule index
Returns the parent label index from the rule index
Returns the right child label index from the rule index
A RuleTopology is basically a grammar with no weights. It provides lookup methods by rule, by parent, etc.