Given a configuration with word w i on top of the stack, as the pointer network just returns a position p from a given sentence, they proceed as follows to determine which transition should be applied: • If p = i, then the pointed word w p is considered as a child of w i ; so the parser chooses a Shift-Attach-p transition to move w p from the buffer to the stack and build an arc w i → w p .
• if p = i, then w i is considered to have found all its children, and a Reduce transition is applied to pop the stack.