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From: tony@artecon.artecon.UUCP (Anthony D. Parkhurst)
Newsgroups: comp.unix.questions
Subject: Re: spell bug?????
Message-ID: <534@artecon.artecon.UUCP>
Date: Tue, 11-Aug-87 12:18:14 EDT
Article-I.D.: artecon.534
Posted: Tue Aug 11 12:18:14 1987
Date-Received: Fri, 14-Aug-87 00:45:59 EDT
References: <541@augusta.UUCP>
Organization: Artecon Inc., San Diego
Lines: 43
Keywords: is this in every system?
Summary: It's the water (algorithm).

In article <541@augusta.UUCP>, bs@augusta.UUCP (Burch Seymour) writes:
 [deleted] ... we discovered, quite
> by accident, that there are patterns of letters which spell accepts
> as real words even though they are nonsense. 
  [deleted]
>  vfppvdu, plbpvhb, and nbclowd

> Is this a known problem? Do these words pass on all unix systems?

Many moons ago, when we received an early (pre-release?) version of
HP-UX (based on System III), we played with spell a bit.  First off,
the words file did not come with source, so since spell had an
option which told you if a word was in the spelling list, we
wrote a program with generated all permutations of letters:
	a b c d e ... z aa ab ac ... zzzzzzzz
and ran it thru spell to generate a source list 
(Yes, we did realize that it would take a LONG time to complete, but
is was fun anyway)

Well, after a couple of hours, we looked at the output and were 
appalled at the nonsence that passed spell.  Many words with no vowels
(which is increasingly difficult to have in the English language 
as the word size grows) with 5 or 6 letters.

We called a support group, then (knowing I would get no response) I called
the division that was working on it. 

Anyway, the answer had to do with the algorithm used by spell.  Somehow
it was designed to catch words that were almost correct, but not
complete nonsense.  They even gave a reference to a published work on
the algorithm, but I have since lost it.

I would assume that since other people say that their speller catches these,
then either their word source is quite different (creating different tables),
or have bugs fixed (if they exist, "that's not a bug, it's a feature"), or
simply use other algorithms that are more correct (but may be slightly slower).

The answer to your question is:  Yes, it is common to UNIX.
-- 
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*  Tony Parkhurst -- {hplabs|sdcsvax|ncr-sd|hpfcla|ihnp4}!hp-sdd!artecon!adp  *
*                -OR-      hp-sdd!artecon!adp@nosc.ARPA                       *
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