@InProceedings{Maas04, author = {Moritz G. Maa{\ss}}, title = {Average-case Analysis of Approximate Trie Search.}, booktitle = {Proc. 15th Annual Symp. on Combinatorial Pattern Matching ({CPM})}, pages = {472--484}, year = 2004, volume = 3109, series = {{LNCS}}, month = jul, publisher = {Springer}, abstract = {For the exact search of a pattern of length $m$ in a database of $n$ strings of (arbitrary) length the trie data structure allows an optimal lookup time of $O(m)$. If errors are allowed between the pattern and the database strings, no such structure with reasonable size is known. Using a trie some work can be saved and running times superior to the comparison with every string in the database can be achieved. We investigate a comparison-based model where ``errors'' and ``matches'' are defined between pairs of characters. When comparing two characters, let $p$ be the probability of an error. Between any two strings we bound the number of errors by $D$, which we consider a function of $n$. We study the average-case complexity of the number of comparisons for searching in a trie in dependence of the parameters $p$ and $D$. Our analysis yields the asymptotic behavior for memoryless sources with uniform probabilities. It turns out that there is a jump in the average-case complexity at certain thresholds for $p$ and $D$. Our results can be applied for any comparison-based error model, for instance, mismatches (Hamming distance), don't cares, or geometric character distances.} }