Prefixaugmented

Prefixaugmented is a term used in computer science to describe a family of data-structuring techniques that extend a base prefix-based structure, such as a trie, by attaching additional metadata to nodes. The augmentation is designed to accelerate queries that operate on prefixes, such as counting, ranking, or listing all words that begin with a given prefix. The concept is not a single standardized implementation but a class of designs that share the idea of enriching the prefix tree with auxiliary information.

In a prefixaugmented trie, each node stores one or more fields in addition to child links. Common choices include subtree_size (the number of words in the subtree rooted at that node), end_mark (whether a word ends at this node), and frequency accumulators. With such data, a prefix query can, for example, return the number of words with a given prefix in constant or logarithmic time with respect to the query length, after traversing the path for the prefix. Enumerating all matches may still require time proportional to the number of matches, but the initial filtering is faster.

Construction and maintenance: insertions, deletions, and frequency updates propagate through affected nodes to keep augmented data consistent. Space overhead depends on the number and type of fields added.

Applications include autocomplete, spell-checking support, and text analysis tools that require rapid prefix-based statistics. Prefixaugmentations may be combined with other structures, such as suffix trees or compressed tries, to balance speed and space.

See also: trie, autocomplete, data structure augmentation.