Re: Reversible sound change applier

Alex Fink writes:

[IPA Zounds]
 > I wonder exactly how it reverses, though?  Having a strong
 > theoretical bent (could you tell, the way I rave about
 > transducers?), one of the things I like about rsca's approach is
 > that the forward and reverse applications of any transformation are
 > (with a few exceptions) precisely inverse relations on strings.  A
 > cursory glance at the source suggests that IPAZounds takes a
 > regular expression approach, and it seems to me much harder to
 > guarantee this property with regexps when the environments of
 > changes can overlap their domains of application.

The reverse applier is not elegant in its internals, but I believe it
copes fairly well in such cases. I would certainly welcome test cases
where it fails, so that I can try to fix them.

It's an inherently complicated business, of course, as you've noted. I
added in some constraints so that the resuts returned are not
overwhelming. There is a length constraint (not more than some
multiplier of the original word long, with a minimum), and the user
can supply syllable definitions which the antecedents must match in
order to be displayed. I've gone round and round on whether to allow
the user to specify a phoneme inventory in order to cut down
possibilities that way - the problem is that in order to be really
useful, it should be an inventory of all the possible intermediate
sounds, so that words can be excluded at each point (thus greatly
reducing the amount of words that need to be computed in the
subsequent steps). Again, I'd welcome people's thoughts on this.

Jamie
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