Comment by b0rsuk | Hacker News Reader

Comment by b0rsuk | Hacker News Reader

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What the article failed to mention is that a very common shuffling method - overhand shuffle - is terrible. You need about 10000 (ten thousand) of them to shuffle an ordinary deck of 52 cards. This can seriously impact you when playing board games, and collectible card games like Magic: the Gathering. In competitive CCGs it can make the game unfair. In non-competitive games it just makes it boring because the same situations tend to occur.

Smushing is a great way to shuffle cards (used on poker tournaments) but it doesn't work if they're sleeved.

For this reason I really appreciate board games which use bags and tokens as card substitutes. It's really the best shuffling method, except that token-sized cards don't have room for text on them. Now that I mention it I'm surprised there are no playing cards in the form of bag and tokens. Probably because ordinary playing cards are so cheap.

On the other hand, with sleeved cards - you can do a "direct" rifle by "cutting" one half of the deck directly into the other (looks a bit like the overhand shuffle, acts more like a riffle).

Something like the second method here ("smash"? Shuffle). Note that the riffle shuffle is also pretty easy with sleeved cards, you just need to modify the technique a bit.

https://youtu.be/nnVABY_a6IQ?t=2m21s

I play a lot of Magic and usually I do this. It’s hard to riffle shuffle a double sleeved 99 card library.

Much easier with a 40 card Limited deck or even a 60 Constructed deck ;)

> You need about 10000 (ten thousand) of them to shuffle an ordinary deck of 52 cards.

My source[0] says the lower bound for full overhand shuffle is number of cards squared, so less than 3000 shuffles for 52 cards. Upper bound around 5000.

Your source?

[0] https://arxiv.org/abs/math/0501401

Well, it seems that his point still stands. Overhand shuffle is terrible for actually shuffling a deck of cards.

Assuming 4 shuffles per second, 3000 shuffles would take about 12.5 minutes, while 10000 shuffles would take more than 40 minutes. One of those sounds feasible during a break on a casual game night.

Of course, those numbers apply only if the shuffle is done literally—I personally try to mix individual cards by letting one hand’s batch cut in-between the other’s (and I think I’m not the only one)—but I’m still curious where did those 10000 come from.

Numberphile, the youtube channel https://www.youtube.com/watch?v=AxJubaijQbI

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