External Hashing Schemes for Collections of Data Structures

The use of external hashing schemes for storing broad classes of data structures is studied The general framework of the paper considers a class of data structures parutioned into smaller classes by the number of positions m the structure For instance, one could start with the class of all binary trees and partiuon that class into the subclasses ~ , % . . . . . each q¢~ comprising all n-node binary trees. The mare results establish nonconstructively the existence of an external hashing scheme h,, with O(n) storage demand and O(1) expected access time that will store any structure in % O q¢2 U . . . U %, provtded ten contains a number of structures growing at most exponenttally m n Classes of data structures subsumed by these results include ragged arrays, binary trees, stringindexed arrays, and refmable arrays