Death Note: L, Anonymity and Eluding Entropy (2017) • Hacker News Board

Re: Death Note: L, Anonymity and Eluding Entropy (2017)

#141

Post by mcms » Wed, Aug 07, 2019, 4:39 AM UTC

Malic wrote: post #23

This is somewhat related to a thought experiment of mine. Suppose you had a means of transmitting information back in time - a one-node network that effectively could email to itself with a timestamp (in the past) being the message's "recipient." Suppose such a thing existed in the world today. Assume the individuals in possession of such a thing were very intelligent, very careful and very guarded about its use. Cou…

Assuming the owner is smart and does not want anyone to detect that such a thing exists, then no one can. As soon as the owner feels that someone else knows, they will send a message back as a warning and tell themselves to be more careful.

Re: Death Note: L, Anonymity and Eluding Entropy (2017)

#142

Post by h1d » Wed, Aug 07, 2019, 7:00 AM UTC

arugulum wrote: post #39

I would frame things a little differently. Light makes a lot of mistakes because the Death note is incredibly powerful and there would be almost no reasonable way for L to catch Light without Light making obvious mistakes (and would also make for a boring story). Undoubtedly, the biggest mistake Light makes is revealing the existence of the Death Note, and all the rules therein, which not only gives L (almost) all th…

It's not about hiding. Light was aiming to rule the world, as in completely eliminate any opposing parties, and you can't kill them without revealing part of yourself.

Re: Death Note: L, Anonymity and Eluding Entropy (2017)

#143

Post by Kaiyou » Wed, Aug 07, 2019, 8:40 AM UTC

faceplanted wrote: post #124

Kaiyou wrote: post #118

Earlier quoted context omitted.

As far as I remember the only reason Light lost at the end is because a character managed to make an exact replica of a Death Note overnight. A magic book that can hold infinite names. It was this plothole that ruined the ending for me.

To be fair to him, it's generally portrayed as a generic black notebook with words on the front, and the only way to notice that lack of infinite pages is to write hundreds or even thousands of names.

I was more concerned with the ability to copy infinite or even just a couple of hundred sites overnight.

Re: Death Note: L, Anonymity and Eluding Entropy (2017)

#144

Post by Liquid_Fire » Wed, Aug 07, 2019, 8:57 AM UTC

cyphar wrote: post #81

Very interesting article, my only real contention is on the point made in Mistake 4: > You can see it was a gamble by considering if Light had been outside Kanto; since he would not see it live, he would not have reacted, and all L would learn is that his suspect was in that other 2/3 of the population, for a gain of only ~0.3 bits. My understanding of L's plan (based on what he said in the broadcast) was that he int…

From a pure efficiency point of view, if you are bisecting like this it is best to divide in halves, which gives you 1 bit of information each time regardless of the outcome.

Of course, this assumes you can continue to apply the same method many times, which probably doesn't apply to this case, as you can only fool Light with a similar method a limited number of times (possibly once only). In that case you probably want to do it more fine-grained than 1/3 so that you get more bits of information once you get to the first (and therefore last) successful attempt.

Re: Death Note: L, Anonymity and Eluding Entropy (2017)

#145

Post by gwern » Sat, Aug 10, 2019, 7:51 PM UTC

teej wrote: post #12

One thing the author seemingly didn't address - the overlap in entropy between the different mistakes. For example, Mistake 2 in timing leaked 6 bits, but those same 6 bits got leaked as a part of Mistake 4 in using confidential police information. Mistake 4 on its own is possibly the worst, but if you consider what L already knows, it's only 5 incremental bits lost. Despite that, loved the article.

Information is defined as relative to existing sets. Mistakes can change how many bits they leak if other mistakes didn't happen - but they did. And in a broader sense, most of these mistakes are dependent on a prior mistake: the FBI team wouldn't've been there if not for the Tailor mistake, and so on.