Re: another kind of infinite compression

Logan Shaw <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> In another thread, Phil Carmody recently talked about the
> theoretical maximum compression ratio of zlib and about
> recompressing gzip data.  This reminded me of a question I've
> had for a while.  The short version is:  is it possible to have
> a compressed archive file that contains itself and some other
> data as well?
> 
> For example, is there any foo.tar.gz that I could extract and
> get a copy of the same foo.tar.gz plus some other file(s)?

Only if the compression is sub-optimal, which gzip probably is in most
cases. If you have a good compression program that reduces the input
close to the entropy of the model, you can't add data that increases
entropy and get the same compressed size.

/Jesper Nordenberg