the optimality of the deductive system) is still assured (proof omitted due to limited space) even with the delayed features incorporated.
because any number of REDUCE-LEFT/RIGHT actions can occur between two SHIFT actions, the delayed features might need to refer to unboundedly deep elements from stack trees; therefore, the boundedness (see Huang and Sagae (2010)) of the kernel features no longer holds and the worst-case polynomial complexity is not assured.