The Theft Protection

Myths and Facts About Identity Theft


A hostile artificial intelligence called
NIM has taken over the world’s computers. You’re the only person skilled
enough to shut it down, and you’ll only have one chance. You’ve broken into NIM’s secret lab, and now you’re floating in a raft on top
of 25 stories of electrified water. You’ve rigged up a remote
that can lower the water level by ejecting it from grates
in the sides of the room. If you can lower the water level to 0, you can hit the manual override, shut NIM off, and save the day. However, the AI knows that you’re here,
and it can lower the water level, too, by sucking it through a trapdoor
at the bottom of the lab. If NIM is the one to lower
the water level to 0, you’ll be sucked out of the lab, resulting in a failed mission. Control over water drainage
alternates between you and NIM, and neither can skip a turn. Each of you can lower the water level
by exactly 1, 3, or 4 stories at a time. Whoever gets the level
exactly to 0 on their turn will win this deadly duel. Note that neither of you can lower
the water below 0; if the water level is at 2, then the only move is to lower
the water level 1 story. You know that NIM has already computed
all possible outcomes of the contest, and will play in a way that maximizes
its chance of success. You go first. How can you survive
and shut off the artificial intelligence? Pause here if you want
to figure it out for yourself. Answer in: 3 Answer in: 2 Answer in: 1 You can’t leave anything up to chance –
NIM will take any advantage it can get. And you’ll need to have a response
to any possible move it makes. The trick here is to start from where
you want to end and work backwards. You want to be the one to lower
the water level to 0, which means you need the water level
to be at 1, 3, or 4 when control switches to you. If the water level were at 2, your only option would be
to lower it 1 story, which would lead
to NIM making the winning move. If we color code the water levels, we can see a simple principle at play: there are “losing” levels like 2, where no matter what whoever starts
their turn there does, they’ll lose. And there are winning levels,
where whoever starts their turn there can either win or leave their opponent
with a losing level. So not only are 1, 3,
and 4 winning levels, but so are 5 and 6, since you can send your opponent
to 2 from there. What about 7? From 7, all possible moves would
send your opponent to a winning level, making this another losing level. And we can continue up
the lab in this way. If you start your turn 1, 3,
or 4 levels above a losing level, then you’re at a winning level. Otherwise, you’re destined to lose. You could continue like this
all the way to level 25. But as a shortcut, you might notice that levels 8 through 11
are colored identically to 1 through 4. Since a level’s color is determined by
the levels 1, 3, and 4 stories below it, this means that level 12
will be the same color as level 5, 13 will match 6, 14 will match 7, and so on, In particular, the losing levels
will always be multiple of 7, and two greater than multiples of 7. Now, from your original
starting level of 25, you have to make sure your opponent starts
on a losing level every single turn— if NIM starts on a winning level
even once, it’s game over for you. So your only choice on turn 1
is to lower the water level by 4 stories. No matter what the AI does, you can continue giving it losing levels until you reach 0
and trigger the manual override. And with that, the crisis is averted. Now, back to a less stressful
kind of surfing.

100 thoughts on “Can you solve the rogue AI riddle? – Dan Finkel

  1. Sign up for free to be emailed the solution to the bonus riddle: https://brilliant.org/teded! Also, the first 833 of you who sign up for a PREMIUM subscription will get 20% off the annual fee. Now go solve some riddles!

  2. Taking a stab at the bonus riddle, is it the single top right corner square? I say this because if you choose that then the only square left for the next player to choose is the square under it, so you could repeat this until they have to choose the death square

  3. Or…you could just…yknow…call in an A-10 wathog and blast holes into the thing until the water drains. Or just call in a nuke, same effect

  4. on bonus riddle..
    i will eat the two on the op so my opponents move is to eat two chocolate or one but if he eat 2 i will eat the 1 so he will die.. when he eat 1 chocolate only i will eat two so he didnt have choice he will die again and again 😂😂

  5. For the last one: Just don't eat the corner.

    If you are an odd number, so you will always win.

    If you are an even number, you'd always loose.

  6. For the candy bar the right two first, then your opponent can either do two squares or one, you pick the last two or one, he dies.

  7. Me: wears hazmat suit with oxygen tank
    Now I can swim and hit the button. Too easy.
    Also, NIM clearly built this chamber. Why not add turrets at the top?

  8. That chocolate bar brings me some memories… Also there's a non constructive proof that for any tablet that is a rectangle (or square) the first player can have a winning strategy, you just don't know which one. In this case, eating only the first top right square guarantees that the first player can win, as far as I can see

  9. "You're the only person skilled enough to shut it down"
    about 10 seconds later: pushes button and shuts down AI
    me: now that's skill right there

  10. Alright this is my answer.
    Step 1: Build a fortress around the tower so the electrified water doesn’t launch into the ocean
    Step 2: Call in as many air strikes as possible.
    Boom, solved.

  11. Imagine if NIM became a reality and this comment is just printed out into a picture and people during the time of NIM would look at this with a grin on their faces saying. ”Heh, amazing how people predicted this.”

  12. For the chocolate one you start on the right and eat 3 chocolates, then if your opponent eats 1,then you eat one, leaving the poisoned one for you opoonent

  13. For the bonus riddle: It really doesn't matter, as long as you don't eat the poisonous square. You can start on any one of them because you're first to eat the chocolate. You would almost certainly die if you went second, but if you go first then you should be fine.

  14. Bonus riddle answer: Eat the upper right corner. No matter what your opponent does, you can always put him in the position that he will have to eat the poisoned chocolate.

  15. i acually use to play a game similar to this with my sister and know the god strategy as long as i have first turn so this is easy

  16. In the 1960s, Dr. Nim took the world by storm as a popular single-player game. NOW, Dr. Nim is taking the World by FORCE as a rogue artificial intelligence, seeking out and eliminating anyone who managed to beat it in the 20th Century.

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