Context sensitive rewrite rules have been widely used in several
areas of natural language processing, including syntax, morphology,
phonology and speech processing. Kaplan and Kay, Karttunen, and
Mohri and Sproat have given various algorithms to compile such
rewrite rules into finite-state transducers. The present paper
extends this work by allowing a limited form of backreferencing in
such rules. The explicit use of backreferencing leads to more
elegant and general solutions.