Date: Thu, 25 Jan 1996 03:32:53 +0200 From: Dmitry Kohmanyuk <dk@dog.farm.org> To: nate@sri.MT.net (Nate Williams) Cc: freebsd-hackers@freebsd.org Subject: Re: FBSD 2.1 Message-ID: <199601250132.DAA13513@dog.farm.org>
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In article <inj.4-30fb29cf-cd3@bee.cs.kiev.ua> you wrote: > > > Copyrights. I don't particularly feel like tangling with either PKWARE > > > or UniSys (LZ compression used in Zip). > > > > The InfoZip zip/unzip is fairly generous with their copyright conditions, > > and they are fairly confident that they are not violating UniSys' or > > PKWare's patents. > I just spend the last few minutes looking through the sources, and it > appears that ZIP doesn't use LZ, but LZW. Apparently they are different > enough to be safe from Copyright problems. well, since I've spent 4 years studying data compression .... ;-) zip uses implode algorithm which is LZ77 aka LZ for compression. unzip supports both LZW (aka LZ768) decompression and LZ77 decompression (and older compression methods left as compatibility with pkzip <1.93 made archives). Unisys patent applies only to LZW. So, it applies to compress(1), GIF format, but not zip. You can just check with Info-Zip team (and specifically, Mark Adler and Jean-Loup Gailly) about this. -- The number you have dialed is imaginary. Please rotate your telephone ninety degrees and try again.
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