5 ms·

The Math Behind “Spot It”

68 points by bobbiechen 5y ago

djbusby 5y ago
There is a Harry Potter flavour one. 55 cards. Very fun.
dugmartin 5y ago
If your kids like Spot It when they were younger they (and you) may enjoy Set (https://boardgamegeek.com/boardgame/1198/set https://boardgamegeek.com/boardgame/1198/set) when they get a little older.
dogsgobork 5y ago
Stand-up Maths did a video on this a few months ago. https://www.youtube.com/watch?v=VTDKqW_GLkw https://www.youtube.com/watch?v=VTDKqW_GLkw including creating a much larger version.
- jgalt212 5y ago
  I dig this channel, but I found this particular explanation hard to follow. That's why I'm about to give the SciAm article a read.
thaumasiotes 5y ago
> Kirkman had actually solved the problem three years prior, when he determined how many schoolgirls he’d need to make the puzzle work. This proof was in response to a question posed in the same magazine in 1844: “Determine the number of combinations that can be made of n symbols, p symbols in each; with this limitation, that no combination of q symbols which may appear in any one of them shall be repeated in any other.” Kirkman extrapolated this as a question of unrepeated pairs in triplets, asking from a certain number of elements, how many unique triplets can you have before you start repeating pairs? This is not an extrapolation. It is a specialization of the problem in which p is 3 and q is 2. If either is an extrapolation of the other, it's the first one being an "extrapolation" of the chronologically-later second.
thaumasiotes 5y ago
> Spot It!, in its distinctive round tin, is hugely popular—it’s in the top ten of Amazon’s list of best-selling card games, right up there with classics such as Uno and Taboo. Taboo is not a card game.
- tom_ 5y ago
  Is it also not a classic?
  - thaumasiotes 5y ago
    It definitely is a classic, but it's not a classic card game. Is Mario Kart 8 on the list of best-selling card games too?
    - Igelau 5y ago
      Mario Kart 8 comes with a deck of cards?
- codetrotter 5y ago
  Depends on your definition. Wikipedia says: > Some games that are placed in the card game genre involve a board. The distinction is that the gameplay of a card game chiefly depends on the use of the cards by players (the board is simply a guide for scorekeeping or for card placement), while board games (the principal non-card game genre to use cards) generally focus on the players' positions on the board, and use the cards for some secondary purpose. https://en.wikipedia.org/wiki/Card_game https://en.wikipedia.org/wiki/Card_game Afaict, the cards in Taboo are the primary driver of the game. And so it seems reasonable to say that it is indeed a card game.
  - thaumasiotes 5y ago
    The cards are not actually used in the game. They serve only to display information. Taboo is a card game in the same sense that Trivial Pursuit is a card game, or that Werewords is a card game. And Werewords doesn't even pretend to have cards involved.
dcdc123 5y ago
That website is toxic on mobile without an ad blocker.
p1itopre 5y ago
https://blog.plover.com/math/finite-projective-planes.html https://blog.plover.com/math/finite-projective-planes.html
jeffwass 5y ago
Another great thing about Spot It is that wide age ranges can play together. There’s some correlation about older kids and adults being better, but really young kids can still easily win a few rounds and build their confidence.
- lemming 5y ago
  I'm not sure I'd agree adults are better, my daughter has been at least as good as my wife and I since she was 6 or so, at least for most of the games. However the one where we can consistently win by a large margin is the one where 9 cards are put out and you have to find groups of 3 across them - for some reason that is much harder for her.
bmsleight_ 5y ago
No longer maintaind, but I did make django-project that automatically generated a pack from a set of images. As the kids and I loved playing a snap like game. It rotated, random-sized etc all the images. https://barwap.com/projects/splendid-snap/ https://barwap.com/projects/splendid-snap/ https://github.com/bmsleight/SplendidSnap https://github.com/bmsleight/SplendidSnap The python script works standalone form the command-line https://github.com/bmsleight/SplendidSnap/blob/master/libspendidsnap.py https://github.com/bmsleight/SplendidSnap/blob/master/libspe...
mensetmanusman 5y ago
Highly recommend the game. While playing it is a fascinating reminder of the limits of our perception and how we pattern match.
MikusR 5y ago
Is this something like rapture. Invented in europe but known only in US?
- ZeroGravitas 5y ago
  In Europe it's called Dobble. https://www.dobblegame.com/en/games/ https://www.dobblegame.com/en/games/
sabujp 5y ago
make your own https://macrusher.github.io/dobble-generator/ https://macrusher.github.io/dobble-generator/
sam_goody 5y ago
There is a great explanation of the math - which is MUCH simpler to follow - at stackoverflow [1] (I have converted that into a JS method for all the golfers here [2]) But there is more to it than just figuring out what pictures go on the card. What's the math to make each image have a unique size? [In Dobble, there are eight images on a card and no two images are the same size. Each image is presented seven times, and the size differs each time.] How do you ensure unique image rotation (which varies similarly to the size)? How to do collision detection so that all the images don't overlap? Also, there are the variations. For example, what is the math to have all images matching EXCEPT one (I have seen this game for sale)? It's fun stuff, but there is more work to do than just what the article reflect. BTW, I would love it if someone has algorithms for the questions I raised. I have been meaning to make a SpotIt! with images of the youth in the group I work at - it would be a unifying present to give out on a overnight. [1]: https://stackoverflow.com/a/47130477/87520 https://stackoverflow.com/a/47130477/87520 [2]: https://stackoverflow.com/a/67409457/87520 https://stackoverflow.com/a/67409457/87520

68 points by bobbiechen 5y ago

There is a Harry Potter flavour one. 55 cards. Very fun.

If your kids like Spot It when they were younger they (and you) may enjoy Set (https://boardgamegeek.com/boardgame/1198/set https://boardgamegeek.com/boardgame/1198/set) when they get a little older.

dogsgobork 5y ago

Stand-up Maths did a video on this a few months ago. https://www.youtube.com/watch?v=VTDKqW_GLkw https://www.youtube.com/watch?v=VTDKqW_GLkw including creating a much larger version.

jgalt212 5y ago
I dig this channel, but I found this particular explanation hard to follow. That's why I'm about to give the SciAm article a read.

thaumasiotes 5y ago

> Kirkman had actually solved the problem three years prior, when he determined how many schoolgirls he’d need to make the puzzle work. This proof was in response to a question posed in the same magazine in 1844: “Determine the number of combinations that can be made of n symbols, p symbols in each; with this limitation, that no combination of q symbols which may appear in any one of them shall be repeated in any other.” Kirkman extrapolated this as a question of unrepeated pairs in triplets, asking from a certain number of elements, how many unique triplets can you have before you start repeating pairs? This is not an extrapolation. It is a specialization of the problem in which p is 3 and q is 2. If either is an extrapolation of the other, it's the first one being an "extrapolation" of the chronologically-later second.

thaumasiotes 5y ago

> Spot It!, in its distinctive round tin, is hugely popular—it’s in the top ten of Amazon’s list of best-selling card games, right up there with classics such as Uno and Taboo. Taboo is not a card game.

tom_ 5y ago
Is it also not a classic?
- thaumasiotes 5y ago
  It definitely is a classic, but it's not a classic card game. Is Mario Kart 8 on the list of best-selling card games too?
  - Igelau 5y ago
    Mario Kart 8 comes with a deck of cards?
codetrotter 5y ago
Depends on your definition. Wikipedia says: > Some games that are placed in the card game genre involve a board. The distinction is that the gameplay of a card game chiefly depends on the use of the cards by players (the board is simply a guide for scorekeeping or for card placement), while board games (the principal non-card game genre to use cards) generally focus on the players' positions on the board, and use the cards for some secondary purpose. https://en.wikipedia.org/wiki/Card_game https://en.wikipedia.org/wiki/Card_game Afaict, the cards in Taboo are the primary driver of the game. And so it seems reasonable to say that it is indeed a card game.
- thaumasiotes 5y ago
  The cards are not actually used in the game. They serve only to display information. Taboo is a card game in the same sense that Trivial Pursuit is a card game, or that Werewords is a card game. And Werewords doesn't even pretend to have cards involved.

dcdc123 5y ago

That website is toxic on mobile without an ad blocker.

p1itopre 5y ago

https://blog.plover.com/math/finite-projective-planes.html https://blog.plover.com/math/finite-projective-planes.html

jeffwass 5y ago

Another great thing about Spot It is that wide age ranges can play together. There’s some correlation about older kids and adults being better, but really young kids can still easily win a few rounds and build their confidence.

lemming 5y ago
I'm not sure I'd agree adults are better, my daughter has been at least as good as my wife and I since she was 6 or so, at least for most of the games. However the one where we can consistently win by a large margin is the one where 9 cards are put out and you have to find groups of 3 across them - for some reason that is much harder for her.

bmsleight_ 5y ago

No longer maintaind, but I did make django-project that automatically generated a pack from a set of images. As the kids and I loved playing a snap like game. It rotated, random-sized etc all the images. https://barwap.com/projects/splendid-snap/ https://barwap.com/projects/splendid-snap/ https://github.com/bmsleight/SplendidSnap https://github.com/bmsleight/SplendidSnap The python script works standalone form the command-line https://github.com/bmsleight/SplendidSnap/blob/master/libspendidsnap.py https://github.com/bmsleight/SplendidSnap/blob/master/libspe...

mensetmanusman 5y ago

Highly recommend the game. While playing it is a fascinating reminder of the limits of our perception and how we pattern match.

MikusR 5y ago

Is this something like rapture. Invented in europe but known only in US?

ZeroGravitas 5y ago
In Europe it's called Dobble. https://www.dobblegame.com/en/games/ https://www.dobblegame.com/en/games/

sabujp 5y ago

make your own https://macrusher.github.io/dobble-generator/ https://macrusher.github.io/dobble-generator/

sam_goody 5y ago

There is a great explanation of the math - which is MUCH simpler to follow - at stackoverflow [1] (I have converted that into a JS method for all the golfers here [2]) But there is more to it than just figuring out what pictures go on the card. What's the math to make each image have a unique size? [In Dobble, there are eight images on a card and no two images are the same size. Each image is presented seven times, and the size differs each time.] How do you ensure unique image rotation (which varies similarly to the size)? How to do collision detection so that all the images don't overlap? Also, there are the variations. For example, what is the math to have all images matching EXCEPT one (I have seen this game for sale)? It's fun stuff, but there is more work to do than just what the article reflect. BTW, I would love it if someone has algorithms for the questions I raised. I have been meaning to make a SpotIt! with images of the youth in the group I work at - it would be a unifying present to give out on a overnight. [1]: https://stackoverflow.com/a/47130477/87520 https://stackoverflow.com/a/47130477/87520 [2]: https://stackoverflow.com/a/67409457/87520 https://stackoverflow.com/a/67409457/87520