in reply to
Re: LZW Demystified
in thread LZW Demystified
Theres an interesting note in the debian ncompress package about this. I have no idea how much to weight to give it or whatnot, but is suspect that as long as nobody is offering this in a package for sale then they cant do anything about it.
Also, only using 256 codes, wouldnt cripple the algorithm it would kill it dead completely. :-) Do you mean that if the table size is fixed at any aribitrary level then its ok?
The following article from James A. Woods, one of the earlier
authors of compress, explains its relationship to the Unisys
patent on the LZW compression method:
+cbvax!agate!iacs!jaw Wed Aug 1 15:06:59 EDT 1990
Article: 1282 of gnu.misc.discuss
From: email@example.com (James A. Woods)
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
# "The chief defect of Henry King
Was chewing little bits of string."
-- Hilaire Belloc, Cautionary Tales 
As a co-author of 'compress' who has had contact with an attorney
Unisys (nee Sperry), I would like to relay a very basic admission from
that noncommercial use of 'compress' is perfectly legal. 'Compress' i
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 pate
#4,558,302. It may be true that some organizations are paying fees fo
data compression technology licensed from one or more of the many hold
of compression patents, but this is all independent from 'compress'.
In particular, I received a letter at NASA dated October 1, 1987
John B. Sowell of the Unisys law department, informing me for the firs
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. Sow
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 a
from Unisys contacts you to extract tribute for the use of 'compress',
tell them that, first, it is not theirs to begin with, and, second, th
someone who will testify in court about the conversation above.
It is not even clear if anyone can "own" 'compress', since original de
Spencer Thomas, myself, and others placed the code in the public domai
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 mod
standard], James A. Storer's work on limited lookahead as explicated i
text "Data Compression (methods and theory)", Computer Science Press,
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.
James A. Woods
NASA Ames Research Center (RIACS)
firstname.lastname@example.org (or ames!jaw)
P.S. The algorithm patent issue certainly is a "topic A" at the momen
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 Co
personally. As a practicing patent attorney, he tells me that, at a m
use of an invention "for research purposes" is legitimate.
<Elian> And I do take a kind of perverse pleasure in having an OO assembly language...