Subject: Re: Copyright restrictions on LZW

From: [email-masked] (Paul Rubin)
Date: 4 Mar 91 02:22:44 GMT

In article <[email-masked]> [email-masked] (Mark Adler) writes:

>   Paul Rubin seems to think:
>
>   >> People who worked on independent
>   >> implementations got screwed because they released their programs after
>   >> LZW was published but before the patent was issued; they had no way to
>   >> know that a patent was pending.
>
>   Well, FSF has raised a big stink about software patents, and
>   rightly so.  It promises to be a hindrance to freedom of expression
>   in software.  However, the Unisys LZW patent hasn't screwed
>   *anyone* with LZW software.  Only people with LZW hardware.  Maybe
>   Unisys will try to screw people in the future, but LZW was too
>   widespread before the patent for this to work.  Anyway, here is a
>   comment from a co-author of Unix compress, which uses LZW: ...

1. Please don't confuse the League for Programming Freedom with the
   Free Software Foundation.  They are totally distinct organizations
   although the sets of people involved with them have a nonempty
   intersection.  The LPF is an membership organization opposed to
   software patents and interface copyrights.  Its membership includes
   commercial software developers and companies as well as GNU
   hackers.  The FSF is a software developer (of free software, as it
   happens) that, like many other developers, endorses the LPF's aims,
   but it has no official connection with the LPF.  It is the LPF, not
   the FSF, that is making all the noise about software patents.

2. I'm glad to hear that the situation with `compress' is not as bad
   as I'd heard.  Woods's letter had information that I didn't know
   about, that clears up some of the questions.  But I'd like to see
   further evidence (such as a document signed by a Unisys officer)
   that Unisys does not intend to hassle users of `compress' and
   software LZW implementations.  Even the letter from Woods only says
   that `compress' is safe for *noncommercial* use and that certain
   big corporations using compress commercially are not paying Unisys
   any license fees, possibly because because they have even more lawyers
   than Unisys.  This doesn't make me feel any better as a small
   developer.

   In particular, I've heard (but have not confirmed) that Phil Katz
   has paid Unisys a substantial fee for a license to use an LZW-like
   algorithm in PKZIP.  If anyone knows more about this, please send
   me mail.

   By the way, what makes anyone think that "LZW was too widepsread
   before the patent for this [Unisys screwing people] to work"?
   For it not to work, there would have to be a publication of LZW
   more than one year before the patent was *applied for* (not issued).
   From Dan Bernstein's posting, it looks like the LZ78 patent may
   be invalid, but not LZW.  

3. Even if `compress' is safe, don't forget there are thousands of
   other software patents pending and issued, waiting to bite people.
   For example, AT&T has started sending nastygrams to members of the
   X Window System consortium saying that the backing store feature in
   X11 (that makes the window system, before displaying a popup menu,
   temporarily copy the image under the menu to off-screen memory and
   restore it when the menu goes away) infringes an AT&T patent, even
   though this technique was in use for years before AT&T started
   using it.  So the original purpose of my posting--to let people
   concerned about this issue know about the LPF--is still as urgent
   as ever.

Thanks for the response about `compress'.  I admire very much the
quality of information that has been showing up in this newsgroup.

---

From: [email-masked] (Mark Adler)
Date: 2 Mar 91 21:15:15 GMT

>> know that a patent was pending.

Well, FSF has raised a big stink about software patents, and rightly so.
It promises to be a hindrance to freedom of expression in software.  However,
the Unisys LZW patent hasn't screwed *anyone* with LZW software.  Only
people with LZW hardware.  Maybe Unisys will try to screw people in the
future, but LZW was too widespread before the patent for this to work.
Anyway, here is a comment from a co-author of Unix compress, which uses
LZW:

From: [email-masked] (James A. Woods)
Newsgroups: gnu.misc.discuss
Subject: Sperry patent #4,558,302 does *not* affect 'compress'
Keywords: data compression, algorithm, patent
Date: 31 Jul 90 22:09:35 GMT
Organization: RIACS, NASA Ames Research Center

     As a co-author of 'compress' who has had contact with an attorney for
Unisys (nee Sperry), I would like to relay a very basic admission from Unisys
that noncommercial use of 'compress' is perfectly legal.  'Compress' is also
commercially distributed by AT&T as part of Unix System 5 release 4,
with no further restrictions placed upon the use of the binary, as far
as I am aware.

     From conversations with Professor Abraham Lempel and others, it
appears that neither AT&T, Sun Microsystems, Hewlett Packard, nor IBM
are paying any sort of license fees to Unisys in conjunction with patent
#4,558,302.  It may be true that some organizations are paying fees for
data compression technology licensed from one or more of the many holders
of compression patents, but this is all independent from 'compress'.

     In particular, I received a letter at NASA dated October 1, 1987 from
John B. Sowell of the Unisys law department, informing me for the first
time that some form of LZW was patented.  I naturally expressed
skepticism that an algorithm could be patented (a murky legal area
which remains so), stated that 'compress' is not identical to LZW,
and in fact was designed, developed, and distributed before the ink
on the patent was dry.  Several telephone conversations later, Mr. Sowell
intimated that they would *not* seek any fees from users of 'compress'
but instead were signing licensees for hardware implementations of LZW.

     So, regardless of what you believe about a shady legal area, if anyone
>from Unisys contacts you to extract tribute for the use of 'compress', please
tell them that, first, it is not theirs to begin with, and, second, there is
someone who will testify in court about the conversation above.
It is not even clear if anyone can "own" 'compress', since original developer
Spencer Thomas, myself, and others placed the code in the public domain
long before the adoption of the Berne copyright convention.

     In light of the events above, it seems that the Free Software
Foundation is being unduly paranoid about the use of 'compress'.
Now I can well believe that FSF is more likely to be a legal target
than a behemoth like AT&T, but if they are simply redistributing
untouched free software developed years ago in the public sector,
I see no problem.

     Aside:  I am investigating, possibly for a case history to be
recycled to USENET, the particulars of data compression patents.
I am aware of the following patents: IBM's Miller-Wegman LZ variant,
those of Telcor and ACT [losing candidates for the British Telecom modem
standard], James A. Storer's work on limited lookahead as explicated in his
text "Data Compression (methods and theory)", Computer Science Press, 1988,
and the various patents pending associated with the Fiala and Greene
CACM article of April, 1989 on textual substitution methods.
If you have any lore, send it this way.

                                      Sincerely,

                                      James A. Woods
                                      NASA Ames Research Center (RIACS)
                                      [email-masked] (or ames!jaw)

P.S.  The algorithm patent issue certainly is a "topic A" at the moment.
One useful reference is the review article by Anthony and Colwell --
"Litigating the Validity and Infringement of Software Patents" in
Washington and Lee Law Review, volume 41, fall 1984.  I know Robert Colwell
personally.  As a practicing patent attorney, he tells me that, at a minimum,
use of an invention "for research purposes" is legitimate.