ambiguous match with multiple-character collating elements

[Karl Heuer]

From:  karl at IMA.ISC.COM (Karl Heuer)

In an environment where the digraph "ch" collates as a single element, what
happens if an attempt is made to match the subject string "chi" with the
pattern "[c[.ch.]]i" or "[c[.ch.]]hi"?  Is the implementation required to
report a successful match in both cases?  If so, it would seem necessary to
use a nondeterministic finite automaton or equivalent, thus making simple
regexp matching and filename globbing as complex as egrep pattern matching.

If you have an answer that's based on something other than your own intuition,
please specify which (draft) standard you're referencing.

Karl W. Z. Heuer (karl at kelp.ima.isc.com or ima!kelp!karl), The Walking Lint

Volume-Number: Volume 21, Number 82