Twenty questions is a weird game
aaronson.orgBack in the 90s as a kid, one year I got a handheld 20 Questions electronic game as a stocking stuffer for Christmas. I remember being astonished that this dumb little plastic pod with rubber Yes/No buttons and LCD screen "beat me" by guessing the first thing I tried (the Mona Lisa) in 8 or so guesses.
The author quips that "twenty questions isn’t enough to guess almost anything", but I wonder if most people taking their first crack at the game (usually as children) pick something squarely in the 2^20 most popular things.
(My friend's dad was really good at picking words. I remember he stumped us for an entire restaurant visit with "the cub in the Chicago Cubs logo".)
My stepson has one- and I was astonished how good it is. I can’t say I’ve thought about it at length but at face value it seems a marvel. Is the logic for such a thing trivial and widely available?
I have no idea how they actually work, but if I were asked to design one:
• Choose some reasonable number of questions of the form "Is it ___"?. Let's say 256
• Come up with a list of objects, and for each one give it a 256-long bitvector encoding its answers to the questions
• Maintain a set (implemented as another bitvector) of the potential items. Figure out which question would divide the set in two most closely; ask that question.
I am the opposite of a hardware hacker or systems programmer, but it seems like this is algorithmically straightforward to implement with bit-twiddling.
One problem with this explanation of how it might work is that it appears to know far more than 256 things - though I don't know how many. And even if it did know only that many, how do you construct the set of questions?
Actually programming the logic once you know it is the easy bit, it's constructing the dataset of answers and questions in the first place.
This approach allows for 2^256 different things, one for each possible yes/no bitstring.
Ah yes, apologies. Still, big job to construct the database of what things correspond to what answers to the questions - and to choose the questions.
> Figure out which question would divide the set in two most closely; ask that question.
This depends on the goal. One goal might be to answer all questions as quickly as possible, in which case partitioning the search space in two might be a good strategy. Another goal might be to have the best chance of guessing the item within 20 questions, in which case you will want to choose questions which maximise the % of the remaining search space you can uniqely identify with the remaining questions (perhaps weighted by popularity of that item).
I think you'd probably start with a dense matrix of questions x answers populated by humans. But I imagine there's a clever preprocessing step that's used to build the optimum tree of questions, avoiding getting caught in a local maximum and significantly reducing the data you'd have to store.
It's been a longstanding question of mine how these things were programmed. How did they construct the database of answers and questions, and what the answer to each question would be for each possible answer?
People could play the game at http://20q.net/ , and if it didn't guess your word it asked you to enter it. So it was trained by the players.
It's a neural net, so very efficient on small devices.
Looks similar to the https://akinator.com
Page is working nicely, albeit with " © 1988-2007, 20Q.net Inc.," in the game pages, -2017 in the front page.
Maybe it's some reinforcement learning.
Apparently it uses a neural network - https://patents.google.com/patent/US20060230008
That last sentence sounds like a pretty magical memory. :)
My family figured out that you could consistently stump those by guessing "poop". Apparently they can't guess that.
This reminds me of jan Misali's analysis of Hangman (in fact the title is so similar that I'm inclined to believe that it's definitely inspired despite not mentioning the video or Misali by name) [^1]. In any case, I'm obviously inclined to agree that they're both weird games, and that the weirdness comes from their fundamental asymmetry. It definitely reminds me of a sort of ritualized play, where an asymmetry is "artificially" constructed for the purpose of being broken down. There's a fictionalized power dynamic that gets produced, yet the erosion of this dynamic isn't just the point, it's often aided by the one in power (how many times have I given my friends hints or extra chances in both games).
> It’s cooperative because everyone is ultimately working toward a common goal: deducing the answer
I think this point gets pretty close to why these games are fun or interesting to begin with. I don't think it's necessarily because that they teach you about a person based on the object they choose or the guesses they make, but the fact that the game operates at all. In some sense it's like a puzzle, but unlike a puzzle doesn't just operate on its prima facie rules - because if you can't solve a puzzle then that's just too bad, but if 20 questions doesn't end then something is off. In seems that 20 questions is interesting because there are social conventions within which it operates and playing by those conventions seems to demonstrate a social and emotional understanding that power dynamics within the relationship will be cooperatively undermined.
o, mi sona e jan ni!
I recently started to learn toki pona after seeing it discussed here, his "12 days of toki pona" series is really great.
A fun thing about Twenty Questions is how old it is.
Here it is in French in 1788, as "The Twelve Questions" but still beginning with the question animal, vegetable, or mineral: https://www.google.com/books/edition/Les_soir%C3%A9es_amusan...
Here it is in English in 1796, as "Game of Twenty": https://www.google.com/books/edition/The_Juvenile_Olio_Or_Me...
I haven't looked too hard for earlier examples in other sources. I see Sorel had a game called the Game of Questions in the 1600s, but it's pretty different: https://wobbupalooza.neocities.org/
The first iPhone app my pal Dave and me put up on the App Store in 2008 was a tip calculator.
The second was 20 Questions. The app provided prompts and a paddle to keep track of the guess count.
It was a nice little app because it made iPhone social.
We called the app iQ because the iProduct pattern was still in force and it was cool to camp the name space.
We sold a bunch of copies of this game, but not nearly as many as we later made on Baby Names, the first baby name app in the App Store.
It was the gold rush era, you could still come up with simple ideas and be the first to put it up on the App Store.
https://web.archive.org/web/20090101213438/http://neutrinosl...
I had a tip calculator back then but it was a dashboard widget for OS X rather than an iPhone app which I just made for personal use. It never occurred to me to try to make an iPhone app out of it, and I was actually looking for an idea just to have an excuse to try iPhone programming.
I know there were already many tip calculators even back then, and they were maybe fine for tips in general like when you are at a restaurant, but I never saw one except for mine that worked well for the most important case: figuring out how much to tip the pizza delivery guy when you are paying in cash.
Say your pizza comes to $16.23. If you usually tip 15% a normal tip calculator tells you that is $2.43 and the total would be $18.66. But who the heck is going to try to pay exactly $18.66 when their are standing in the open door with their home's precious heat leaking into the cold winter night? Same with handing him $20 and waiting for him to count out $1.34 in change.
What most sane people are going to do is hand him $19 and say "keep the change", or hand him $20 and say "keep the change", or hand him $20 and say "give me $1 back".
With my calculator you would enter the $16.23 price, and the calculator would give you a table something like this:
You can then easily combine that with your tipping level goal, tipping limit, and the mix of bills in your wallet to figure out what to do to leave an acceptable tip while still having a quick transaction.Pay Tip $17 4.7% $18 10.9% $19 17.1% $20 23.2% $21 29.4%Could be your app still has legs, slotted into wherever a widget like this might make sense in the Apple ecosystem. IIRC, Amazon has a program allowing plugins for Alexa that your solution might be good for.
I searched around for a screenshot and found one with an images and a description of our tipping app, Tiptotaler.
It apparently got an A- rating from ilounge at the time, which is heartening still today. :) [1]
App functionality description:
> You can separately input food, drinks, and tax into three fields at the top of the screen, then note the number of drinkers and non-drinkers, set the tip amount, and then get totals for individual diners.
[1] https://www.ilounge.com/index.php/articles/comments/iphone-g...
> 20 questions is not a word game
I find this ironic, as the author treats it like a word game. I've always played that it has to be a "thing" by the typical sense of the word, e.g. an object. Sometimes with bounds, like something you saw today. The problem with "intangible things" is they are essentially imaginary, and therefore subject to the whimsy of the answerer, as they point out. Does an Air Guitar make noise? Is an Air Guitar a gesture, what about a form of dancing?
Objects don't have that problem but still can make for incredibly interesting games.
This is why the flexibility of humans is great.
> Does an Air Guitar make noise?
"Maybe, but only in your mind" or "not directly by itself"
> Is an Air Guitar a gesture,
Yes.
> what about a form of dancing?
"Yeah, I guess it is'
A small nit:
> As John Green (or Georg Cantor) taught us, some infinities are bigger than others—and the number of things is a really big infinity
I don't think this statement is true, at least not in the context it's given. At most, we'd only be able to think of countably many things, which is the smallest infinity.
Is that right?
So if a set is infinite but a provably strict subset of another - would we not say that set/infinity is smaller?
No, because with infinities, even if a set is a subset of another, you may still be able to find one element in the first set that corresponds to every element of the other set.
For example, the natural numbers are a subset of the whole numbers, but there is a natural number that corresponds to every whole number. To see this, we can order the whole numbers like this: {0, -1, 1, -2, 2, -3, 3, ...}, and we can easily see that we can now assign one natural number to each of them (0 -> 0, -1 -> 1, 1 -> 2, -2 -> 3, ...). Since you'll never run out of naturals, you won't ever find a whole number that doesn't have a corresponding natural number.
Since assigning a natural number this way is equivalent to counting the elements of the other set (in this scheme, I could say that -2 is the 3rd whole number), this type of infinity is called "countable infinity". The natural numbers, the whole numbers, and the rational numbers are all countably infinite. In contrast, the irrational numbers and the real numbers are not. In fact, even the real interval [0, 1] is not countable, so this interval is considered to have more elements than N (the set of natural numbers).
Note that while there is only one countable infinity, there are many uncountable infinities - so not all uncountably infinite sets are considered as large. If you're curious about this area, the study of these concepts is done via "transfinite numbers" - particularly, the transfinite cardinal numbers (there are also transfinite ordinals).
Surprisingly, no. For example, even though every whole number is also a rational number, mathematicians would say the size (or more accurately, the cardinality) of the set of whole numbers is the same as that of the set of rational numbers.
I'm personally a fan of the Infinite Hotel Paradox as an introduction to the subject.
Not only is the answer "no" like the sibling comment says, but in fact one definition of an infinite set is that it can be put into one-to-one correspondence with a strict subset of itself. In other words, infinite sets are precisely those for which your concept of size doesn't work.
Another sibling comment used the even/odd example, but that's not necessary to dispel this particular misconception. Consider the set of non-negative integers and the set of positive integers. That is, {0,1,2,3,...} and {1,2,3,4,...}. The latter is a strict subset of the former. Maybe I have just done mathematics for too long, but to me these are intuitively, "obviously" the same size. What would it even mean for one of them to be smaller? Which one is the same size as {-1,-2,-3,...}, if either of them? Even doing folk mathematics, if the size of the first is "infinity" then the size of the second is "infinity minus one which is still infinity".
There are the same number of even integers as there are even and odd integers
If they are the same number what number is it.
It's called ℵ 0 (Aleph 0).
I like when someone asks a question that looks snarky, maybe rhetorical like saying "what you are saying is nonsense, look, this question cannot be answered", but then there is a perfectly valid answer
The answer isn't all that valid. ℵ₀ is just a name defined by the statement "the number of integers is ℵ₀". You could also call it Bob. If you don't think Bob would be a valid name, you should reject ℵ₀ too.
The name isn't unique either; by definition, ℵ₀ is equal to ℶ₀. This should be a clue that the term ℵ₀ is not actually meant to identify the number in question. Rather, what's going on is that there is a conceptual system of ℵ numbers, and another conceptual system of ℶ numbers, and the number at index 0 in each of those systems is the cardinality of the naturals.
But I don't think Bob is a valid name because if I use it to refer to the cardinality of the naturals, nobody would know what I'm talking about.
I don't see why I have to reject aleph null just because I reject Bob.
If it were called "Bob", students would inevitably read their profs' handwriting as "eight hundred six", leading to all sorts of hilarious confusion.
> ℵ₀ is equal to ℶ₀
That's the definition of ℶ₀. So of course they are equal.
"Two" is also just a name for the successor of 1. I could also call it "bob" and thus "two" would not be unique, but I don't see the point. The fact is that the cardinal of countable numbers is a mathematical concept which has a name, and can be manipulated. Which is what matters, and what the parent poster maybe did not understand.
> "Two" is also just a name for the successor of 1. I could also call it "bob" and thus "two" would not be unique, but I don't see the point.
There is no point, because 2 is well defined.
That is also true of the ℶ numbers, but it is not true of the ℵ numbers. That's why, in that case, it's necessary to have multiple names for the same number.
> The fact is that the cardinal of countable numbers is a mathematical concept which has a name, and can be manipulated.
No, that's not a fact, that's what I'm saying.
The cardinality of the naturals is a mathematical concept. It is referred to as "the cardinality of the naturals", or by many similar phrases.
But it is not referred to by the name ℵ₀. ℵ₀ is a name that refers to a different concept, the cardinality of the ordinal number ω. The two cardinalities are equal, but ℵ₀ specifically refers to one of them, conceptually, rather than the other.
ℶ₀ refers to a different concept again. That's the one that is meant to be manipulable.
You could (using "is a subset" as a partial order), but you can't make a total order. Any way you try to compare size of sets where neither is subset of the other, while preserving your intuition of "size" will run into trouble.
You make "the ordinals" sort of using your idea, but that isn't really measurement of "size"; it's more like an assignment of ranks.
But you can also think of any real number, such as pi or e, which came from an uncountable set.
You can't think of any real number. You can think of some of them, but you need to have a way of thinking of them with some specification that can be written down, and those form a countable set. We also have finite life spans, so we actually can only think of finitely many numbers. When you think of the natural numbers, you think of them as a set and concept, which is different than being able to visualize and conceive of every natural number.
What about potentially think of? Even that does not make sense because every possible description you can think of must be written with finitely many symbols in some language, and all such descriptions form a countable set.
Therefore, there are real numbers that could never be written down in English, even potentially. Of course, that partially also depends on the kind of axiom system that you are using. In effect, the standard axioms of mathematics state the existence of things that cannot be effectively specified, which some people actually are against, although such people form a minority.
The surprising thing is that we can effectively reason with large infinities and such objects make intuitive sense (the set of all functions from the natural numbers to the natural numbers is uncountable but a very natural sounding set), and yet it is impossible even in principle to write every one down, even with an unlimited amount of time.
Real numbers do not make intuitive sense. The continuum makes some sense. A countably subset of the reals makes sense. The rest of the reals (almost all of them) are beyond comprehension, except in vague description like "an infinite string of digits" and for proofing paradoxes like Banach-Tarski.
Pi and E can be thought of because there are mathematical formulas and algorithms relating them and computing them. There are only countably many such formulas & algorithms.
You can't think of an arbitrary real number, in the sense of distinguishing it every other real number(including nearby reals an ε away from it), and with no other constraints besides being a real number.
it's simple, we'll count the number of epsilons we need away from the nearest described number... wait...
> But you can also think of any real number
I don't think that's true. We can certainly think of certain numbers which we gave a name to and have defined it in some way. But there are a _lot_ of real numbers.
We could think about it this way: we can only describe (and therefore think of) numbers using a finite number of symbols out of a finite alphabet. That makes it only countable.
But, unless you have predefined a language, you can't know which countable set is expressible, so the union of all possible sets may be uncountable.
But I think all languages is countable, so it should be a subset of the product of two countable sets, which should be countable?
Can we think of any computable number?
And then some uncomputable ones if we give them a name/concept.
It seems quite wild
There are computable numbers whose minimum expression requires more bits than the universe can hold, using any possible encoding the universe has sufficient bits to define.
Infinity is much bigger than any finite number. This includes even "all possible numbers reachable in all possible finite encodings of a number within a given size", as inconceivably large as that is. No matter how large that set is, somewhere, there is some maximum number that is the largest possible number you can specify under the conditions I've given here, and that number is 0% of the way along the number line, which means that 100% of all "computable numbers" are larger than than that number.
There are some uncomputable numbers that have been given names. We even have the first few digits of some of them. See for instance: https://en.wikipedia.org/wiki/Chaitin%27s_constant
What does it take to think of a number? We can certainly refer to particular uncomputable numbers - choose an enumeration of Turing machines, and let x be the real number whose binary expansion has 1 at the i-th place if the i-th Turing machine halts, and 0 otherwise.
Pi and e come from an uncountable set, but the set of things you can think of is almost certainly countable.
I played this game with physicist friends and the favorite word was 'shadow'. It was the only everyday object not composed of something in the standard model. It stumped everyone.
Can you even call something intangible an everyday object?
Technically the color Pink is white light minus the color green. Whereas shadow is light minus some light. Is Pink intangible also?
Yes, going by the definition of "sensible by touch" for tangible. That would make something like smoke intangible.
That's a good one. I also like 'hole'.
"Smoke" is often a good one to stump.
Is a song an object?
Is a ghost?
A finish line?
My kids used to have this 20 questions toy. It was always able to figure out anything I thought of in less than 20 questions. Apparently, I’m terrible at coming up with things to guess. Now I want to find that toy, put in new batteries, and try it against the list of things mentioned at the bottom of this article.
I'd love to try "that toy" as the answer. My bet is that whoever developed it would definitely have considered that possibility, though!
I recommend werewords for a twist on Twenty Questions and the best version of Werewolves - the hidden role deduction game.
Some players know the word but want to ask misleading questions but with out the other players noticing.
Sounds like a fun one to try with my siblings at Thanksgiving, thank you!
A community built, evolving one for characters: https://en.akinator.com/
Its genuinely hard to find someone (real or fictional) who it can't find!
You can play this with voice via Alexa which adds to the magical feel when trying it with younger kids.
It can even guess things like "me" or "my little sister" correctly.
Came here to share Akinator… Glad to see it’s still running, we used to play it at school (15 years ago!) as it was one of the only web games they didn’t block :)
>You might be thinking, wait, if there are infinitely many things to narrow down, couldn’t the game take infinitely long? Theoretically, maybe, but in practice, no. This is kind of a paradox. Even though we can conceive of infinitely many things, any particular thing will be guessable in a finite number of questions. After all, the answerer can only reach so far into the infinite depths of the universe before they decide on a thing
It's probably not like the answerer has access to more than, say, 1M things - I mean as things they can juggle in their mind and pick among.
Let's say recording artists: there are 100s of thousands of them globally. But a regular person will perhaps know/recall at best 100-1000 max distinct ones, even if they have heard 2x or 3x others. And they'd be the most likely another would know too.
Or let's take numbers: those can be constructed (you don't need to know a number ahead of time to think of it - I can think of 2345324532435245 but I didn't have that in mind as something I've encountered already, I just know that that would be a number, I just need to pile on digits to come up with one). So, yes, this would overflow the "set of items to pick". But "I'm thinking of the specific number X" is not commonly or ever part of the 20 answers game.
(Still, if the first N questions make it clear that it's a number that was picked, the next 20 - N ones could try to binary search it).
Or let's consider animals and insect: there are 20,000 types of beetles alone. But nobody will put an unknown "beetle type X" (say, "Sitophilus granarius") as the item they think. They'll either think of "beetle" in general, or at best some well known beetle type.
One insight is that if the other person doesn't even know of the thing you have in mind, or is not fun guessing it with questions (like a specific huge number), then it makes no sense to pick it, as part of the implicit game rules is for others to have a chance and everybody to have some fun (as opposed to "win at all costs").
I wonder how people who start off with “is it bigger than a breadbox?” do if the item is in fact a breadbox? I would not be surprised if a lot of people take “no” to mean it is smaller than a breadbox overlooking that breadbox sized objects would also get a “no”.
This occurred to me once so I tried challenging my wife to a game of twenty questions, and her first question was, “is it a breadbox?”. Annoyed, I challenged her to a rematch, to which she replied, “is it bread?”, and won again.
That's exactly what happens in the video linked in the article in that paragraph.
Why is the question "is it bigger than a breadbox?" rather than "is it bigger than a loaf of sliced bread?"? Surely there's less size variation in the latter...
Brewdbox is easier to say, and was used in the game since before sliced bread was as popular as it is today, and breadboxes can range in size in the same way as bread that contains them.
It's one of the questions where, if it's a scale (e.g. weight or size), the answer is right in the middle instead of either end.
My PhD project is to work on language model capable of playing the answerer in a Twenty Questions game (reverse of Akinator). If you are interested you can play here: https://twentle.com It is meant as a party game to play on your mobile with the learderboard on a large screen (like Quiplash)
On the back-end is a GPT-3 model answering the questions with: never, rarely, sometimes, always or usually.
I tried it for a very few seconds (on lunch, will return) and showed it to a few non-native english speakers: very interesting, especially for them.
One thing - instead of the 'is it an animal' intro, perhaps you could put 'ask your question here'.
Thanks for the suggestion! Changed it to 'ask your question here...'
Do they see this game as good way to practice their English?
It's killing me that if I run out of time, I never get to find out what the word was. could you tell me what word three was for https://www.twentle.com/p/2358 ?
Indeed, I'll change that so you can see the word after you run out of time/questions. The word was belt.
We play this with our kids on car rides with some regularity. We usually limit scope to some book series- LOTR, Harry Potter, Star Wars, etc. Kids get really annoyed when I pick something super obscure like “a hair on Gandalf’s beard”. So I do. But they know it’s my strategy so can often guess anyway. If you know the owner skews towards obscure you can weight the binary search towards obscure.
I literally read the whole post thinking it was by Scott Aaronson, until I found the signature "Adam" at the end.
The beginning could have been Scott Aaronson, and I expected it to continue with some incredibly deep insight on how anything in the universe cannot be described in a small number of bits, but anything humans can think of can, etc etc.
It didn't quite go there but a fun read regardless.
His name is also at the top of the page on the banner...
Twenty Questions metaphor on understanding Quantum Mechanics by Phillip Ball
Quantum Mechanics Isn’t Weird, We’re Just Too Big by Phillip Ball
https://youtu.be/q1O11kP6x1k?t=2366
Short thesis : According to quantum mechanics, the universe doesn't make up its mind till you ask it to.
> Short thesis : According to quantum mechanics, the universe doesn't make up its mind till you ask it to.
Or, in CS lingo, the universe is lazily evaluated.
Real World [runs on] Haskell.
There's an excellent story about an early mainframe version of this game called ANIMAL that copied itself into a new directory each time it was played:
One of the questions my friends and I have made mostly standard for tangible things is “can you buy it at Target”. Not all tangible things can be bought, and not all things that can ge bought are for sale at Target, but it’s a broad enough set that it’s proven to be reasonably effective. Plus, none of us own breadboxes.
"Can you buy it at Target" is a good one, I'll try it next time.
I and my exgirlfriend play this game back in those days. One time she chose 'arrows on traffic sign' really got me frustrated. Sometimes she answers my question as an object in our physical world, and sometimes she answers me with its semantic meaning. Reminds me of Gödel's incompleteness theorems.
>Sometimes she answers my question as an object in our physical world, and sometimes she answers me with its semantic meaning.
When we play this game with famous real/fictional people, this happens all the time. Sometimes there is even a three-way ambiguity. The character to guess is: Barbie.
"Is she older than 50?"
"Yes" (the concept)
"Have I ever talked to her?"
"Yes" (the doll)
"Is she an athlete?"
"Yes" (the character)
This is why I enjoy No More Jockeys [0] (in small doses), a game show between three UK comedians. The rules are:
* Going around the circle, each player names a person and a category into which that person belongs (e.g. "William Shatner, no more actors")
* Without taking notes, the next person continues and so forth.
* If a player believes another player is in violation of any of the categories, they may formally issue a challenge. If the challenge is valid, that player is eliminated, otherwise the challenger loses one of their (2) allowed challenges.
The show works great because all 3 players are comedians and old friends, so they love to get ridiculous and varied with it.
Categories might be "No more people whose name fits iambic pentameter" or "No more people who any of us had a crush on" or "No more people who have probably used a microwave before".
Persons might be "Noah" or, as you mention, "Barbie". Resolving a challenge like "Well, how old is Barbie, really?" are solved sometimes through discussion or sometimes through a player promising to abide what Wikipedia says before the third, uninvolved player, looks it up.
Kind of off topic: Many years ago, I was learning to be an electrician. Whenever I had a hard time picking up a concept on layouts or some components, an old timer would tell me "You don't know the right questions to ask." I've carried that simple and wise saying with me ever since.
I would say yes to "is it tangible" for a dragon, but TFA implies that the author would say no. Thoughts?
There's a school of language philosophy that says that the existence of a dragon is a false premise, and thus that every predicate is true for it. Others would claim that such sentence aren't true nor false. The archetypical example is "The king of France is bald".
However ... no theory of (natural) language has been consistent with human judgement, so all these attempts to formalize semantics should be take with a large grain of salt. They are attempts, not even theories.
> Others would claim that such sentence aren't true nor false. The archetypical example is "The king of France is bald".
This depends on whether you’re a Legitimist or an Orleanist. And even then, the Orleanist claimant is only “balding”, looks to be around 4 or so on the Norwood scale.
Out-of-touchists, more likely. Imagine squabbling about the legitimacy of the Treaty of Utrecht.
An episode of the BBC Radio programme "In Our Time" discussed this. https://www.bbc.co.uk/programmes/b04v59gz
That's why it's a bad question that only works in group of friends where it has been established what tangible means.
Can you touch one? No because they don't exist, so not tangible.
The thing that I imagine in my head when someone says "dragon" is something that I could touch (just as much as the thing I imagine in my head when someone says "apple" is something that I could touch).
I can't touch the Colossus of Rhodes as it no longer exists, but that doesn't make it tangible, so it need not exist right now. If someone genetically engineers a dragon in the future, does that retroactively make dragons tangible today?
Still very much open to different interpretations. Again, very bad question overall that shows that the author only plays this with the same group of friends where rules are predefined.
Is anything fictional tangible?
Let's say there's an apple in a biography from the 19th century. That apple has long since biodegraded. Is it somehow more tangible than an apple from a novel?
Is the ghost of a human a mammal?
I don't think human ghosts are mammals, but for some reason that surprises me. I guess maybe my instinct is that mammals are a class of physical creatures, but mammal-ness seems simultaneously an inherent part of human-ness. I'm not sure what to do with this information.
under Thomistic philosophy, yes.
A friend of mine once told me he got stuck at the first "is it tangible" question with trying to answer whether or not "Germany" was tangible. Depends if you are referring to the landmass or the concept I suppose.
I hate playing these kinds of games, at least with most people, because they simply can’t answer the questions correctly. It’s frustrating beyond belief. Just one example, I once narrowed it down to a fictional character, so I asked “Was it invented after 1980?” and got a “yes”. The answer, after many failures, was Alice in Wonderland. I’m sure it’s my brain that just works differently here, but I can’t for the life of me figure out why people would choose subjects they don’t know the most basic facts about.
>but I can’t for the life of me figure out why people would choose subjects they don’t know the most basic facts about.
Because most people think of something hard to guess as opposed to something they know a lot of facts about. Part of being good at 20 question is being good at handling wrong answers to your questions.
Production grade 20 question AIs do not just do a binary search because it is too easy for the human to make a mistake in answering and then the computer won't win. In order to improve the chances of winning, the AI must be robust against a small percentage of wrong answers being given to it.
To play the devil’s advocate, it isn’t a clear question. Invented is ambiguous, and there are certainly works created after that date, such as movies and video games. If they meant the book, then yes, of course it’s a bad answer.
It’s a game though, not an exercise in pure logical deduction.
He said it's the character, which has no ambigous creation date.
My aunt was known for thinking of something tricky. Once she chose "the paint on the walls". We were well past 20 questions by the time we got it.
"Is it alive?" is a classic trap because it may create a broken state if it's a person that is dead. You will never know how someone will respond to "yes, but no" facts, and since it's such an important question you may end up in the wrong half if there's a mismatch between your interpretations.
Probably the question that leads to most "but you said!" situations.
Very true. I usually ask "is or was it ever alive", and if yes I'll then ask if it's alive today.
Edit: don't know how the similar sibling comment didn't appear to me when I was writing this, since it's from 4 hours ago and I loaded the page less than one hour ago...
So the correct question should be something like "Is it, or has it ever been, alive?"
In German, the game is called “Ich sehe was, was du nicht siehst”, literal translation “I am seeing something that you are not seeing”, and I feel this addresses two issues the author has:
Being able to see something narrows down the universe of things quite considerably. This is about the tangible/intangible difference.
The number of questions is not limited.
> Even though we can conceive of infinitely many things, any particular thing will be guessable in a finite number of questions.
I don't think that's true. If you choose a random number between 0 and 1 you'll need an infinite number of questions to guess the number.
If you pick a number between 0 and 1 its going to either be a rational number, or is going to use a known irrational number (pi or sqrt(5)). In both cases it can be guessed in a finite number of guesses.
That's not true. The set of numbers between 0 and 1 is uncountable, which means that has a cardinality bigger than the natural numbers, ie: you can't build a bijection between [0, 1] and the natural numbers. Therefore, to fully specify any number in [0, 1] you'll need an infinite number of guesses.
There's an uncountable number of numbers between 0 and 1, but you, a human, can only pick from a countable subset of those.
But the number picker specified the number in their head to themselves before the game began.
> If you choose a random number between 0 and 1 you'll need an infinite number of questions to guess the number.
How would you do that?
We are typically playing that game in domain of "characters in child animation/films/books". So my first typical questions are "Is it a boy or a girl?" and "Is he/she a prince/princess?"
I would first establish if it's an animal or a human.
I think an AI that plays twenty questions would be interesting…
AIs playing 20 questions was one of the great delights of yesteryear!
And before that https://www.fourmilab.ch/documents/univac/animal.html
20 questions was a solved problem long before “AI”. It’s just a kind of binary search. These little pocket devices would blow my mind as a kid
https://duckduckgo.com/?q=20+questions+electronic&iax=images...
There has been one for years: http://20q.net/
You can chain unrelated predicates through disjunction to create more specificity.
e.g. Is it ((a thing you can hold) \/ (a mathematical construct you can't hold))?
I can't believe its not that Aaronson.
idle thought, given 20 questions you can ask any questions that can be answered with a yes or no, what would the smallest number of questions to guess a number between 1 and a million?
I don't think you can do better than a binary search here, so log2(1000000) questions, which happens to come out to 20 with rounding.
I tried thinking a bit outside the box for other questions that would break down the search space - but none of them were any improvement on the binary search.