1 Introduction
1.1 The External-Memory Model
1.2 Lazy Search Trees
1.3 Related Work
1.4 Contribution
2 The Gap Structure: A New Restricted External Biased Search Tree
2.1 Buckets by Weight and Searching by Element
2.2 Updating the Weights
2.3 Supporting Rank Queries
3 The Interval Structure
4 Lazy B-Trees
5 Open Problems
A The Interval Structure
A.1 Invariants and Potential
A.1.1 Merging Intervals
A.1.2 Potential
A.2 Updating Elements of the Intervals
A.3 Splitting the Intervals
A.3.1 Gap i is 2-sided.
A.3.2 Gap i is 0-sided.
A.3.3 Total I/O Cost
B Supporting Lemmas