text: The co-host of the Pittsburgh call-in show "Left Out" was the first author on the paper that showed that the distance between two of these with n elements is at most 2n − 6.  
full_question: The co-host of the Pittsburgh call-in show "Left Out" was the first author on the paper that showed that the distance between two of these with n elements is at most 2n − 6.  That distance is defined in terms of operations that preserve order but change structure called rotations, which is the first step of the Day-Stout-Warren algorithm.  The CART algorithm forms the "decision" type of these structures, and the red-black type of these structures is among those that keep their height limited in response to additions or deletions; those are the self-balancing binary search variety of these structures. For 10 points, name these data structures that contain “root” and “leaf” nodes.
first_sentence: The co-host of the Pittsburgh call-in show "Left Out" was the first author on the paper that showed that the distance between two of these with n elements is at most 2n − 6.  