Re: Workaround for compress patent?

["brian (b.c.) white" <bcwhite@bnr.ca>]

>> I wonder if it wouldn't be possible to convert gzip files to compress
>> files without recompressing?  I haven't seen the patent, but it's just
>
>Umm, gzip and compress are very different algorithms; gzip was
>*written* to avoid the patent (see also "yabba" done slightly before
>it.)

Gzip wasn't written to avoid the patent...  It is just a completely
different algorithm.  It's actually the same algrithm used in pkzip2.0.

Let's see...  If I remember correctly, it's some kind of sliding-window
pattern matching with shano-fanno optimization...  Or something like
that.

>However, I was under the impression that the
>reason gzip supported "uncompress" was because the patent covered
>compression, not decompression... regardless of the more recent
>unisys/CI$ claims.

This is correct.  Only compression is covered by the LZW patent,
which incidently only covers the "Welch" addition, which just
improves on the storage of the compressed stream generated by
Lempel-Ziv.

                                        Brian
                                 ( bcwhite@bnr.ca )

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