Another Lemma
consider single step of splay operation (case I, II or III)
- let r(P) denote the rank of P before the operation
- let r’(P) denote the rank of P after the operation
Cost of Splay Steps Lemma
- A splay step involving node P, the parent of P and possibly the grandparent of P can be done with an investment of at most 3(r’(P)-r(P)) new dollars, plus one more dollar if this was the last step in the splay