Kaizhong Zhang

Simple fast algorithms for the editing distance between trees and related problems

Ordered labeled trees are trees in which the left-to-right order among siblings is significant. The distance between two ordered trees is considered to be the weighted number of edit operations (insert, delete, and modify) to transform one tree to another. The problem of approximate tree matching is also considered. Specifically, algorithms are designed to answer the following kinds of questions:1. What is the distance between two trees? 2. What is the minimum distance between

On the editing distance between unordered labeled trees

T_1

Comparing multiple RNA secondary structures using tree comparisons

and

Alignment of trees: an alternative to tree edit

T_2

On the complexity of comparing evolutionary trees

when zero or more subtrees can be removed from

A General Edit Distance between RNA Structures

T_2

A system for approximate tree matching

? 3. Let the pruning of a tree at node n mean removing all the descendants of node n. The analogous question for prunings as for subtrees is answered.A dynamic programming algorithm is presented to solve the three questions in sequential time

A constrained edit distance between unordered labeled trees

O(|T_1 | \times |T_2 | \times \min ({\textit{depth}}(T_1 ),{\textit{leaves}}(T_1 )) \times \min ({\textit{depth}}(T_2 ),{\textit{leaves}}(T_2 )))

Some MAX SNP-hard results concerning unordered labeled trees

and space

Exact and approximate algorithms for unordered tree matching

O(|T_1 | \times |T_2 |)