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Comment by asimpletune | Hacker News Reader

Yeah, I mean until we have ternary transistors, emulating ternary circuits will be less efficient than actual binary circuits. If we ever have ternary transistors, then ternary circuits will be an improvement over binary ones.

Here's a little ternary logic riddle for the HN community:

Two people are sitting at a restaurant, deciding what to order. Neither had communicated with one another when the waiter appears and asks one of them "Is everyone ready to order?". They reply "Hm, I don't know". The other person immediately then says "Now we are." Why?

(As in, how did the second person know?)

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Spoiler:

If the first person did not want to eat, he would have answered "No, we are not ready". Him not being ready is enough to negate the whole thing. He doesn't know if the both of them are ready to eat though, because he doesn't know that the second man is ready or not (the second man hasn't revealed his state yet).

Therefore, the second man knows that the first is ready to eat, since the first's answer is "I don't know". Since the second man knows that he himself is ready to eat, he can answer: "we are both ready to eat".

Person A does not know because they don't whether Person B is ready. If Person A was not ready themselves they would know the answer is No. We assume here that people know wherher they themselves are ready.

Person B then can safely assume Person A is ready and if they are ready themselves they are now indeed ready.

If the first person was not ready to order, he would know that everyone is not ready to order. Since he doesn’t know, that means he is ready to order, but is not aware of the second person readiness.

So the second person knows that the first person is ready

Added fun: This riddle can be generalized to N people sitting at a restaurant :)

O haha, yeah, that one is super mind bending. I heard a riddle that used that trick once about people being able to leave an island when they know what their eye color is. It's super cool because it feels like you're basically embedding memory into a purely logical expression, since you're allowed to assume that all the islanders (or in the case above, diners) are perfectly logical, and therefore by logic alone a counter of sorts emerges.

Not sure if I explained that part well, but I can write the riddle somewhere and share it one day, since it needs to be explained more precisely to demonstrate this N-people effect.

https://www.youtube.com/watch?v=98TQv5IAtY8

That assumes person A has figured out if person A is ready, and assuming that is not a good idea in the real world.

It also assumes they're directly answering the question instead of indirectly answering it.

> That assumes person A has figured out if person A is ready

Not sure I understand that. Did you mean it assumes that person B has figured out that person A is ready?

I didn't have a typo. Also I'm going to use names now because letters are hard to read.

The way Bob found out that Alice was ready was because Alice was uncertain about group readiness.

Maybe Alice was uncertain because she knew her own readiness but not Bob's readiness. This is the way the riddle works.

But maybe Alice wasn't sure of her own readiness. In that case Bob should not answer.

And, second issue, what if Alice was saying "Hm, I don't know [what to pick]." as a way to tell the waiter that no, everyone is not ready.

> But maybe Alice wasn't sure of her own readiness

I'm not sure I understand how Alice could be unsure of her own readiness. If she's not ready, then she would have said "no, everybody is not ready to order."

> And, second issue, what if Alice was saying "Hm, I don't know [what to pick]." as a way to tell the waiter that no, everyone is not ready.

Because the riddle is "how did he [Bob] know?". We are told from the start that Bob is right, and asked to explain why.

> I'm not sure I understand how Alice could be unsure of her own readiness. If she's not ready, then she would have said "no, everybody is not ready to order."

You don't understand how someone can be unsure if they're ready? Have you never been kind of anxious or indecisive before? (The answer is definitely not "you're not ready until the anxiety and indecision are gone".)

> Because the riddle is "how did he [Bob] know?". We are told from the start that Bob is right, and asked to explain why.

There's a reason I said "in the real world".

For best results, generalise to N, and have everyone remain silent for a short time, before someone (or everyone simultaneously, your choice) answers “yes”.

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