| 摘要 |
An enumerator employs "indexing volumes" as the add-on values used to compute indexes for n-item ordered sets such as symbol sequences. Each indexing volume is associated with a different class into which the allowed ordered sets are partitioned. The indexing volumes all equal or exceed the number of ordered sets that belong to their respective classes. Additionally, the indexing volume V<SUB>i </SUB>associated with a given class of i-item equals or exceeds the sum of the indexing volumes associated with the classes that contain the (i-1)-item prefixes of the ordered sets that belong to the given class. The indexing volumes are quantized such that each volume V=wr<SUP>s</SUP>, where r is an integer greater than unity, s is a non-negative integer, w is a positive integer less than r<SUP>m</SUP>, m is some positive integer less than h, and, for some allowed ordered set whose size is less than n, h is the number of radix-r digits in the smallest quotient that results from evenly dividing by a positive-integer power of r the set count of the class to which that allowed ordered set belongs. As a result, the addition operations used to compute the indexes can be performed with limited precision, and storage requirements for the add-on values can be relatively modest.
|
