5 ms·

> He didn't say "okay, but there will be a 256 byte size penalty per additional file", he just plainly agreed. Exactly. IMO the challenge-setter is the one be

> He didn't say "okay, but there will be a 256 byte size penalty per additional file", he just plainly agreed. Exactly. IMO the challenge-setter is the one being more unfair here, since his metadata-based reason to reject the solution applies to submissions made under the original rules too. He accepted an amendment without counter-amending to cover that loophole, so if he stands by his word, he has to pay up. It casts doubt on whether he would pay if somebody won by the original rules with some luck. Maybe he has an implicit allowance, that merely two files can't "encode" a big enough advantage, but again, then it's his fault for not addressing that in the new rules.

thret 12y ago
It's effectively a prop bet. If you're a world class table tennis champion and you bet someone you can beat them at table tennis on the proviso that they get to pick the bats, you can't really complain if you find out later that they have spent six months practicing with frying pans. You just have to pay up. If you don't see the loophole before you agree, you pay. Actually there's a great little bit about this in the movie Guys And Dolls (1955), and what to do if someone bets you that he can make a jack of spades squirt cider in your ear.
emn13 12y ago
Note that he never guaranteed to leave the files with the same file names, and without that, Patrick's trick wouldn't have worked. Given the fact that Patrick made the rules concerning multiple files, and that they were intentionally tricky, I think it's fair to interpret them in that spirit - as a trick. Notably, even without the ordering there is still some information leakage purely in terms of file sizes, but that's a little harder to exploit (likely still possible with a 3mb file). Of course, the rules don't explicitly state the directory must be otherwise empty... Frankly, I think it's pretty reasonable that Patrick "lost" the bet, even if Mike reasoning wasn't sound. For Patrick to have won that bet would have required quite a list of requirements of how those "other" files were to be passed to the decompressor. Such requirements were not presented, and if they had been they would have been obviously fishy.
- Dylan16807 12y ago
  He could have ordered the files by size pretty easily. Trick still would have worked. No fancy requirements needed. Just making the files available in any manner. And yes there needs to be a way to know which file(s) are the compressed data, that loophole would disqualify any entry.
  - hyperpallium 12y ago
    Clever, he'd likely be skipping many 5's towards the end, but still compresses. Another scheme: chop it up into files of increasing length, the difference being 1..256, encoding a byte (ignore the last difference). EDIT more efficient to increase in length by 1 or 2, encoding a bit.
  - emn13 12y ago
    Yep, file sizes alone leak sufficient information to be an issue, but it's a bit of a hypothetical because that's not what actually happened. Clearly, Mike shouldn't have allowed multiple files (or should have specified some kind of overhead for multiple files), and clearly there are other tricks Patrick could have used, but with these unfortunate rules and this submission nothing seems to require keeping file order intact. It's a good point about needing to know which files are compressed. On a philosophical level, I'm not sure whether that means there actually should be a way to know which file(s) are the compressed data, or that the rules are simply broken...
    - Dylan16807 12y ago
      What I'm trying to argue is that any justifiable objection Mike could have made would have failed. Unjustifiable objections could have been made but screw those, because they would cause legitimate compression to fail. Unjustifiable objections will pretty much always exist if the rules are written in English. That doesn't mean the rules are broken, it means you use judgement and follow the purpose of the rules. Mike's fate was sealed when he allowed multiple files without an overhead penalty. He could have removed all the metadata possible, simply having the files exist as separate entities was enough to ruin him.

thret 12y ago

It's effectively a prop bet. If you're a world class table tennis champion and you bet someone you can beat them at table tennis on the proviso that they get to pick the bats, you can't really complain if you find out later that they have spent six months practicing with frying pans. You just have to pay up. If you don't see the loophole before you agree, you pay. Actually there's a great little bit about this in the movie Guys And Dolls (1955), and what to do if someone bets you that he can make a jack of spades squirt cider in your ear.

emn13 12y ago

Note that he never guaranteed to leave the files with the same file names, and without that, Patrick's trick wouldn't have worked. Given the fact that Patrick made the rules concerning multiple files, and that they were intentionally tricky, I think it's fair to interpret them in that spirit - as a trick. Notably, even without the ordering there is still some information leakage purely in terms of file sizes, but that's a little harder to exploit (likely still possible with a 3mb file). Of course, the rules don't explicitly state the directory must be otherwise empty... Frankly, I think it's pretty reasonable that Patrick "lost" the bet, even if Mike reasoning wasn't sound. For Patrick to have won that bet would have required quite a list of requirements of how those "other" files were to be passed to the decompressor. Such requirements were not presented, and if they had been they would have been obviously fishy.

Dylan16807 12y ago
He could have ordered the files by size pretty easily. Trick still would have worked. No fancy requirements needed. Just making the files available in any manner. And yes there needs to be a way to know which file(s) are the compressed data, that loophole would disqualify any entry.
- hyperpallium 12y ago
  Clever, he'd likely be skipping many 5's towards the end, but still compresses. Another scheme: chop it up into files of increasing length, the difference being 1..256, encoding a byte (ignore the last difference). EDIT more efficient to increase in length by 1 or 2, encoding a bit.
- emn13 12y ago
  Yep, file sizes alone leak sufficient information to be an issue, but it's a bit of a hypothetical because that's not what actually happened. Clearly, Mike shouldn't have allowed multiple files (or should have specified some kind of overhead for multiple files), and clearly there are other tricks Patrick could have used, but with these unfortunate rules and this submission nothing seems to require keeping file order intact. It's a good point about needing to know which files are compressed. On a philosophical level, I'm not sure whether that means there actually should be a way to know which file(s) are the compressed data, or that the rules are simply broken...
  - Dylan16807 12y ago
    What I'm trying to argue is that any justifiable objection Mike could have made would have failed. Unjustifiable objections could have been made but screw those, because they would cause legitimate compression to fail. Unjustifiable objections will pretty much always exist if the rules are written in English. That doesn't mean the rules are broken, it means you use judgement and follow the purpose of the rules. Mike's fate was sealed when he allowed multiple files without an overhead penalty. He could have removed all the metadata possible, simply having the files exist as separate entities was enough to ruin him.