🚀 go-pugleaf

In article <1990Aug2.200440.7101@bellcore-2.bellcore.com>,
karn@envy.bellcore.com (Phil R. Karn) writes:
|>
|>PKZIP also makes use of a new compression scheme Katz calls
|>"implosion", and it seems to do much better than his LZW
|>implementation in PKARC.  It even seems to outdo tar+compress under
|>UNIX, which is remarkable given the PC's limited memory and PKZIP's
|>compression of individual files.
|>
|>Does anybody know how "implosion" works, and whether it might be an
|>alternative to LZW?  It would be pretty satisfying to tell Unisys to
|>take a hike because we've found a more efficient algorithm that's
|>public domain...
|>
|>Phil
             
There's a so-so explanation in some of the docs for PKZip. 
(ADDENDUM.DOC is the name of the file.)  It's a cruddy explanation, but
PK does say that (if memory serves) he dedicates the algorithm to the
public domain.  I'll see if I can go dig addendum.doc out and quote it.

Also, PKZip's done a better job on every tar.Z file that's crossed my
path.  I normally work with MS-DOS, but I still get a bunch of 'em.  And
about PKZip compressing individual files...  It basically does the same
thing that the compress and tar combo do, but it also lets you extract
individual files.  The extra space from uncompressed headers is minimal.

One tiny other thing...  I wouldn't doubt if Unisys's patent is said to
only hold on the particular hardware setup, as one can't patent a
current algorithm.  That might not sway a judge, but the response with
DOS users after those letters in DDJ was "So what?  They gonna stop us
all?"  LZW compression is extremely well entrenched with PC users.  (We
need it for our "limited" hard disk space...  <GRIN>)


					E=MC squared,
					E. Jason Riedy

Internet: ejr@mosquito.cis.ufl.edu
===============================================================
My opinions are my own, and are therefore correct.  ;-)