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Edit Distance with Move Operations
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Edit Distance with Move Operations
Dana Shapira6 and James A. Storer6 
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Computer Science Department, Brandeis University, Waltham, MA, 02254 |
Abstract
The traditional edit-distance problem is to find the minimum number of insert-character and delete-character (and sometimes
change character) operations required to transform one string into another. Here we consider the more general problem of strings
being represented by a singly linked list (one character per node) and being able to apply these operations to the pointer
associated with a vertex as well as the character associated with the vertex. That is, in O(1) time, not only can characters
be inserted or deleted, but also substrings can be moved or deleted. We limit our attention to the ability to move substrings
and leave substring deletions for future research. Note that O(1) time substring move operations imply O(1) substring exchange
operations as well, a form of transformation that has been of interest in molecular biology. We show that this problem is
NP-complete, show that a “recursive” sequence of moves can be simulated with at most a constant factor increase by a non-recursive
sequence, and present a polynomial time greedy algorithm for non-recursive moves with a worst-case log factor approximation
to optimal. The development of this greedy algorithm shows how to reduce moves of substrings to moves of characters, and how
to convert moves with characters to only insert and deletes of characters.
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