The ADT proximity and text proximity problems
Ricardo A. Baeza-Yates, Walter Cunto · 2003
Practical text proximity problems lead to the abstract data type proximity that handles close points in the plane. Different variants and implementations of proximity are proposed and tight-complexity bounds based on information theory are derived. This problem is related to evaluating Boolean queries in large text retrieval (as in Web search engines) and to the "Sorting X+Y" problem.