Groups > comp.lang.java.programmer > #8678

Re: Playful puzzle

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From	Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at>
Subject	Re: Playful puzzle
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Roedy Green <see_website@mindprod.com.invalid> wrote:
> I offer this is the spirit of play. It is not a serious problem.
:-)

> Lets say you had a PAD file that among other things included the
> zipped size of the distributable inside it in ASCII bytes.  But the
> PAD file itself is inside the distributable.
> In the worst case, how many times must you adjust the size in the PAD
> and rezip with java.util.zip if you want to be 100% sure it is bang on
> accurate?

In the worst case, you might never ever get a bang:

e.g. you start with number 00000, and may get a zipped file of 55554 bytes,
then you write 55554 (with a tiny bit more entropy) and now get 55555 bytes.
Then you write 55555 (which that tiny bit less entropy) and get 55554 bytes...

PS: I have no idea, if such cycles will really show up, but it appears
  plausible to me that they could...

PPS: there may, however be a way out:   By giving a slightly larger size
  and a means to add further entropy into the pad-file or into an extra
  file of the distributable, you can add just as much rubbish, until the 
  initial size-overestimate is reached - and if it is surpassed rather than
  reached, then re-iterate with incremented size-estimate.

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Thread

Playful puzzle Roedy Green <see_website@mindprod.com.invalid> - 2011-10-09 03:45 -0700
  Re: Playful puzzle Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-10-10 15:29 +0000
  Re: Playful puzzle Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2011-10-10 11:53 -0700

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