Shuffling less is often good enough.

http://science.slashdot.org/article.pl?sid=08/11/14/1438252 "You may have heard that it takes about seven shuffles to mix up a deck of cards to near randomness. Turns out, though, that most of the time, perfect randomness is more than you need. In blackjack, for example, you don't care about suits. The same mathematician who developed the original result now says that for many games, four shuffles is enough. And the result isn't only important for card sharks. It helps reveal the math underlying Markov Chain Monte Carlo simulations, telling applied mathematicians when they can stop their simulations." would take a little adapting to vtes i guess. -- salem (replace 'hotmail' with 'gmail' to email) "In *my* Assamite deck, this would pwn you in teh FAEC, so shut up." "Thats only cos u've never sene mi Gionavvi PUNCHnMUCNH u asshat." - James Coupe

On Nov 14, 5:09 pm, Salem <kella...@hotmail.com> wrote: > http://science.slashdot.org/article.pl?sid=08/11/14/1438252 > > "You may have heard that it takes about seven shuffles to mix up a deck > of cards to near randomness. Turns out, though, that most of the time, > perfect randomness is more than you need. In blackjack, for example, you > don't care about suits. The same mathematician who developed the > original result now says that for many games, four shuffles is enough. > And the result isn't only important for card sharks. It helps reveal the > math underlying Markov Chain Monte Carlo simulations, telling applied > mathematicians when they can stop their simulations." > > would take a little adapting to vtes i guess. > I wonder how "good" the shuffles need to be. Because if I start with a well-ordered deck, seven shuffles isn't even enough. I suppose it depends on what you consider a shuffle. Seven riffle shuffles is only going to move the top card down about 10 cards or less most of the time, unless you mix in some overhand shuffles in there. 4 riffle shuffles with an overhand shuffle in between is likely to be enough to take a deck that is somewhat random already and randomize it, assuming that the shuffles are neither "perfectly" executed (if each shuffle puts exactly one card from each pile in between each two cards from the other pile, it's not random, now is it?), nor too haphazardly executed (20 from one pile, 20 from another, rest of the first pile rest of the second pile... that's not going to randomize very much either). But with a perfectly ordered deck, I feel like at least 10 shuffles are required before I no longer see obvious patterns from the original ordering. Granted, that's not scientific, it's just a "feeling", but I doubt 4 shuffles, no matter how well executed, can really randomize an ordered deck, unless it's a table shuffle that just spreads out all the cards and mixes them around.

[ quoted text not captured ] I have been experimenting with something, but am unsure as to its legality. The idea is to take a deck, define the optimum layout of cards, then number all cards from 1-90. This is done by inserting a paper slip with the numbers on it into the face side of the sleeve the card is in. I then shuffle, doing 3 riffles and 3 overhands. I find this gives an incredibly good spread, allowing optimum card flow. The question remains whether the original "Stacking" is legal. It could be argued that it does not matter what order you start from, so whether it is the same 1-90 order or randomly ordered, as long as there is sufficient shuffling afterwards. I would actually like a response from LSJ on this, as it is a highly efficient system which I do not use in tourneys simply to not knowing the legal status of it.

Blooded Sand wrote: > I have been experimenting with something, but am unsure as to its > legality. > > The idea is to take a deck, define the optimum layout of cards, then > number all cards from 1-90. This is done by inserting a paper slip > with the numbers on it into the face side of the sleeve the card is > in. I then shuffle, doing 3 riffles and 3 overhands. I find this gives > an incredibly good spread, allowing optimum card flow. The question > remains whether the original "Stacking" is legal. It could be argued > that it does not matter what order you start from, so whether it is > the same 1-90 order or randomly ordered, as long as there is > sufficient shuffling afterwards. > > I would actually like a response from LSJ on this, as it is a highly > efficient system which I do not use in tourneys simply to not knowing > the legal status of it. If the original order matters, then the subsequent shuffling is not sufficient.

[ quoted text not captured ] The original orders matters only so far as it is the most even spread of cards. I f you are saying that it is illegal because of the original order, then for all sets of order of cards, there is no suffficient subsequent shuffling. If the order is Random, alphabetical, grouped into type or whatever form, it still has some kind of initial order. In exactly the same manner, if I then, before every game, spread my deck out, evened the cards out manually, then shuffled, this would be illegal. Which is a bit tricky as quite a few people already do this. This is also the same as saying that using the 6/8 card shuffle, where everything is divided into separate piles is illegal, as in this layout the order is defined as being important, even though it is a randomised order. (Arguing with a 39 C fever is maybe not the wisest course in the world though)

Blooded Sand wrote: > On Nov 15, 12:13 pm, LSJ <vtes...@white-wolf.com> wrote: >> If the original order matters, then the subsequent shuffling is not sufficient. > > The original orders matters only so far as it is the most even spread > of cards. I f you are saying that it is illegal because of the > original order, then for all sets of order of cards, there is no > suffficient subsequent shuffling. If the order is Random, > alphabetical, grouped into type or whatever form, it still has some > kind of initial order. If the original order matters in any sort of intentional or predictable way to the ultimate ordering of the deck after shuffling, then that shuffling is not sufficient.

[ quoted text not captured ] But by the same token, ANY initial order, whether preordained or random, matters to the eventual order of the deck. If the shuffling itself is not enough to guarantee a sufficient level of randomness, then all shuffling becomes insufficient. It does not matter from what state you start in if the idea of shuffling is to create a randomisation of the set. However if the argument is that shuffling does not introduce a high enough level of randomness, then any and all initial ordering is suspect, no matter the cause of that specific order. By the same token, if the shuffling IS an agreed method of introducing a sufficient level of randomness, then the inital order makes no difference.

Blooded Sand wrote: > On Nov 15, 12:53 pm, LSJ <vtes...@white-wolf.com> wrote: >> Blooded Sand wrote: >>> On Nov 15, 12:13 pm, LSJ <vtes...@white-wolf.com> wrote: >>>> If the original order matters, then the subsequent shuffling is not sufficient. >>> The original orders matters only so far as it is the most even spread >>> of cards. I f you are saying that it is illegal because of the >>> original order, then for all sets of order of cards, there is no >>> suffficient subsequent shuffling. If the order is Random, >>> alphabetical, grouped into type or whatever form, it still has some >>> kind of initial order. >> If the original order matters in any sort of intentional or predictable way to >> the ultimate ordering of the deck after shuffling, then that shuffling is not >> sufficient. > > But by the same token, ANY initial order, whether preordained or > random, matters to the eventual order of the deck. True, but moot. We're discussing different methods of randomization, not different methods of selecting a starting order. See "intentional or predictable". > If the shuffling > itself is not enough to guarantee a sufficient level of randomness, > then all shuffling becomes insufficient. Incorrect. If the shuffling method in question (say, 4 riffles) is not sufficient, that in no way implies that all shuffling methods (say, 90 card spread mix picked up in the order indicated by 90 sequential tosses of a d100) are insufficient. > It does not matter from what > state you start in if the idea of shuffling is to create a > randomisation of the set. ... if the randomization method is "sufficient", correct. If the randomization method is insufficient, then, by definition, the starting state matters. > However if the argument is that shuffling > does not introduce a high enough level of randomness, then any and all > initial ordering is suspect, no matter the cause of that specific > order. OK. > By the same token, if the shuffling IS an agreed method of introducing > a sufficient level of randomness, then the inital order makes no > difference. That's what I said, yes.

In message <f333b8eb-e6f3-4e1d...@d10g2000pra.googlegroup s.com>, Blooded Sand <sand...@gmail.com> writes: >The original orders matters only so far as it is the most even spread >of cards. If it's giving you a noticeably better flow of cards after the shuffle, however, then the original order mattered. Similarly, Magic players who try to stack a land every third or so card are trying to stack their decks. The theoretical perfect shuffle is unlikely to be possible. However, if you're getting better results when you start from one order than if you start from another, you're: a) not shuffling enough b) cheating (possibly unintentionally). Some players have suggested when shuffling using a dice during a pile shuffle. e.g. pile the deck into 1d6+3 piles, a few overhand shuffles, some riffling etc., then do it again for 1d8+2 piles, and so on. -- James Coupe PGP Key: 0x5D623D5D YOU ARE IN ERROR. EBD690ECD7A1FB457CA2 NO-ONE IS SCREAMING. 13D7E668C3695D623D5D THANK YOU FOR YOUR COOPERATION.

In message <2710dd62-a649-4419...@k1g2000prb.googlegroups .com>, Blooded Sand <sand...@gmail.com> writes: >But by the same token, ANY initial order, whether preordained or >random, matters to the eventual order of the deck. If the shuffling >itself is not enough to guarantee a sufficient level of randomness, >then all shuffling becomes insufficient. No, that's not true. You start with a deck that's got mostly action modifiers at the top and mostly actions at the bottom. You riffle shuffle it once, and get a fairly predictable flow of actions and action modifiers. Clearly, this is not sufficient. With the same deck, you riffle shuffle it, cut it somewhere at random, riffle shuffle it again, pile shuffle it into 1d6+3 piles, a few overhand shuffles, cut it again, riffle shuffle it again, ask another player to cut it for you, pile shuffle it into 1d8+2 piles, overhand shuffle, riffle shuffle again, get someone else to cut the deck in two, riffle shuffle the two halves, pile shuffle each half into 1d4+3 piles, stack each half back together, and then riffle shuffle the two halves back into one. That's much more random. The order is far less predictable. This has introduced several more random elements into the process - dice, other people, some overhand shuffles. The first single riffle shuffle is clearly insufficient. The second arrangement is clearly much more random, and so may well be sufficient. It doesn't attempt to produce a better flow based on the original sorting. A sufficiently randomized deck should, once in a blue moon, come up with the deck in alphabetical order. In tournaments past, there have been issues where a judge did a deck check. They handed the deck back to the player in deck-list order. Various players then wanted to sort the deck into a "more random" order before shuffling, because starting from deck-list order would screw them. Problem: if your shuffling is good enough, the original order doesn't matter, the outcome will be exactly as unpredictable regardless of where you start from. [ quoted text not captured ]

James Coupe schrieb: > In tournaments past, there have been issues where a judge did a deck > check. They handed the deck back to the player in deck-list order. > Various players then wanted to sort the deck into a "more random" order > before shuffling, because starting from deck-list order would screw > them. Problem: if your shuffling is good enough, the original order > doesn't matter, the outcome will be exactly as unpredictable regardless > of where you start from. Agreed. What I would like to see is a tournament rule that gives a minimum requirement for "good enough" shuffling. Most people are not math geniuses (including me) so that would be really helpful. -- If playing against Cock all you need to remember is: Don´t get caught by Cock.

[ quoted text not captured ] So my original point was that I riffle shuffle 3 times, mixed with 3 overhand shuffles. Is this not sufficient enough to make it random? because at a certain point, more shuffling will actually result in a less random result. Strange, but true. All i want to do is start from a sufficiently homogenized position, and then shuffle. Why is this any different from taking your deck after play and making sure there are no clumps?

In message <231c75d2-0052-4918...@a26g2000prf.googlegroup s.com>, Blooded Sand <sand...@gmail.com> writes: >So my original point was that I riffle shuffle 3 times, mixed with 3 >overhand shuffles. Is this not sufficient enough to make it random? Apparently not, based on your own words: "I find this gives an incredibly good spread, allowing optimum card flow." Since you are getting "incredibly good" results, your shuffling is clearly insufficient. > All i want to do is start from >a sufficiently homogenized position, and then shuffle. The question is why. If your shuffling is good enough, it doesn't matter if you start from a homogenized position - it's just a waste of time ordering the deck to start with. If your shuffling isn't good enough, which it clearly isn't because your stacking is having an effect on your result, then clearly this is the wrong thing to be doing. >Why is this any >different from taking your deck after play and making sure there are >no clumps? People unclumping their decks are saying "My shuffling isn't good enough." A good, thorough shuffle overrides unclumping. If it doesn't, you're not shuffling enough. If your shuffling is good enough, you pick up your deck whatever state it's in - ordered, unclumped, clumped, ordered by artist surname - and the result is equally unpredictable. Clearly, there are some practical concerns - few shuffles are perfect. However, you have already told us that the stacking you do is resulting in a better outcome. Therefore: a) your shuffling isn't good enough b) you are cheating. [ quoted text not captured ]

Blooded Sand wrote: > On Nov 15, 1:26 pm, LSJ <vtes...@white-wolf.com> wrote: >> Blooded Sand wrote: >>> By the same token, if the shuffling IS an agreed method of introducing >>> a sufficient level of randomness, then the inital order makes no >>> difference. >> That's what I said, yes. > > So my original point was that I riffle shuffle 3 times, mixed with 3 > overhand shuffles. Is this not sufficient enough to make it random? Probably not. Certainly not if you can afterwards perceive anything about the initial sorting or grouping or homogenization of the deck. > because at a certain point, more shuffling will actually result in a > less random result. Strange, but true. This false perception comes from a common misunderstanding of what "random" is. Random doesn't mean that the various categories of cards in the deck will be uniformly distributed through the deck. It means that each possible ordering of the deck, including the ones in which each group of cards in the various categories are clumped together, is equally likely. > All i want to do is start from > a sufficiently homogenized position, and then shuffle. Why is this any > different from taking your deck after play and making sure there are > no clumps? It is no different. Both suggest improper shuffling. Proper shuffling (sufficient randomization) means that the starting set up has no predictable bearing on the final distribution of cards in the deck. Which means that any effort spent adjusting the initial order or clumping or homogeneity of the deck before shuffling is wasted.

On Nov 15, 5:13 am, LSJ <vtes...@white-wolf.com> wrote: > > If the original order matters, then the subsequent shuffling is not sufficient. > But the original order could determine the amount of shuffling required to be sufficient, can it not? If the deck was already in random order, then it will still be randomized after 1 shuffle. If the deck is mostly random - say I played a game and got ousted on turn 6, then took the cards that I had played and put them back in the deck - then only a few shuffles will re-randomize it. If I take those cards I played during the game and put them in pseudo-random spots in the deck instead of just stacking them on top, I believe that it would take still fewer shuffles to sufficiently randomize. So, I guess the question becomes this: Taking a deck that is grouped with all like cards next to each other - if you pile-shuffle it, does the entropy of the deck go up? I think yes. On the other hand, nobody really likes "mana-weaving." It just wastes our time because it takes so much longer than riffle shuffling.

Chris Berger wrote: > On Nov 15, 5:13 am, LSJ <vtes...@white-wolf.com> wrote: >> If the original order matters, then the subsequent shuffling is not sufficient. >> > > But the original order could determine the amount of shuffling > required to be sufficient, can it not? No. > If the deck was already in > random order, then it will still be randomized after 1 shuffle. Uh. By convention, the thing called "original deck" is not in random order. Obviously, if the deck is randomized, then it only takes "no action" to randomize it. > If > the deck is mostly random - say I played a game and got ousted on turn > 6, then took the cards that I had played and put them back in the deck > - then only a few shuffles will re-randomize it. Probably not. But I suppose if you drew only your initial seven cards on those six turns and handed the still-randomized-and-unseen remaining deck and the seven cards to a judge to randomly insert into the deck, then it would take fewer shuffles to randomize that mostly-random deck than it would a known-state deck. But all of this is just smoke. It doesn't help make the point clear and it may actually distract from the point. > If I take those > cards I played during the game and put them in pseudo-random spots in > the deck instead of just stacking them on top, I believe that it would > take still fewer shuffles to sufficiently randomize. Nah, since you know the positions of those insertions as well as the distance between those various insertions. > So, I guess the question becomes this: Taking a deck that is grouped > with all like cards next to each other - if you pile-shuffle it, does > the entropy of the deck go up? I think yes. Yes. Indeed, taking a deck in any condition (other than pure random) and shuffling it properly increases the entropy. (Pure random already being maximum entropy, so shuffling it only maintains the entropy level rather than increasing it). > On the other hand, > nobody really likes "mana-weaving." Perhaps, but I don't know what that is. [ quoted text not captured ]

In message <2HDTk.6246$Ei5....@flpi143.ffdc.sbc.com>, LSJ <vte...@white-wolf.com> writes: >Chris Berger wrote: >> On the other hand, >> nobody really likes "mana-weaving." > >Perhaps, but I don't know what that is. Inserting land at every third card in a Magic deck. (Or any other insertion strategy, relevant to a particular deck.) There were some periods of time at which the DCI said this was legal, then they said it wasn't, then there was fun with players who intentionally pile-shuffled decks into 3 piles (to unweave the land) before shuffling, and so on. [ quoted text not captured ]

On Nov 15, 11:32 am, LSJ <vtes...@white-wolf.com> wrote: > Chris Berger wrote: > > > If > > the deck is mostly random - say I played a game and got ousted on turn > > 6, then took the cards that I had played and put them back in the deck > > - then only a few shuffles will re-randomize it. > > Probably not. But I suppose if you drew only your initial seven cards on those > six turns and handed the still-randomized-and-unseen remaining deck and the > seven cards to a judge to randomly insert into the deck, then it would take > fewer shuffles to randomize that mostly-random deck than it would a known-state > deck. > > But all of this is just smoke. It doesn't help make the point clear and it may > actually distract from the point. > Who said I was trying to make your point *clearer*? ;) > > If I take those > > cards I played during the game and put them in pseudo-random spots in > > the deck instead of just stacking them on top, I believe that it would > > take still fewer shuffles to sufficiently randomize. > > Nah, since you know the positions of those insertions as well as the distance > between those various insertions. > But you don't know the exact position of the insertions any better than if you overhand shuffled. Theoretically, when you overhand shuffle, you "know" that the top, say, 15 cards are now the bottom 15, the next 27 are now the next 27 from the bottom, etc... If you don't count where you insert the cards into the deck, and assuming you insert them face down without looking at them, it's very close to random. > > On the other hand, > > nobody really likes "mana-weaving." > > Perhaps, but I don't know what that is. > I'm nearly certain that you do. I suppose that pile-shuffling and mana-weaving aren't exactly the same thing. Maybe I'm using the wrong terminology, but I take pile shuffling to be laying the deck out into a pre-determined number of piles (James's version using a die is better - I like that), in order, one card per pile - I don't think it's technically a shuffle because it isn't random. Mana weaving would be putting, say, a Master card every 3rd card in your deck, putting one bleed and one stealth card next to each other... arranging the deck in some sort of crazy way before shuffling. I've always kinda considered pile-shuffling to be mana weaving because, while you're not looking at it, you're still spreading out the master cards in an even way, etc... I lump them together moreso because of the amount of time it takes. I can't believe that there's any faster way to randomize your deck than riffle shuffling it, with overhand shuffles mixed in, until it's "ready". Sitting at the table mana-weaving or pile-shuffling should be considered a delay of game if it causes a tournament director to not be able to start a round on time (or to cause a game to start after the round has already started). And I agree with what I think was your rule (I could be wrong?), that stacking your deck is illegal because if it accomplishes anything, it is cheating; and allowing it leads to an easy opportunity to cheat by not sufficiently randomizing after stacking.

Chris Berger <ark...@ugcs.caltech.edu> wrote: > Salem <kella...@hotmail.com> wrote: >> http://science.slashdot.org/article.pl?sid=08/11/14/1438252 >> >> "You may have heard that it takes about seven shuffles to mix up a >> deck of cards to near randomness. Turns out, though, that most of >> the time, perfect randomness is more than you need. In blackjack, >> for example, you don't care about suits. The same mathematician who >> developed the original result now says that for many games, four >> shuffles is enough. And the result isn't only important for card >> sharks. It helps reveal the math underlying Markov Chain Monte Carlo >> simulations, telling applied mathematicians when they can stop their >> simulations." >> >> would take a little adapting to vtes i guess. > > I wonder how "good" the shuffles need to be. The definitive article: http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&id=pdf_1&handle=euclid.aoap/1177005705 Kevin M., Prince of Las Vegas "Know your enemy, and know yourself; in one-thousand battles you shall never be in peril." -- Sun Tzu, *The Art of War* "Contentment... Complacency... Catastrophe!" -- Joseph Chevalier Please visit VTESville daily! http://vtesville.myminicity.com/ Las Vegas NAQ 2009 http://members.cox.net/vtesinlv/

On Nov 15, 6:34 am, Johannes Walch <johannes.wa...@vekn.de> wrote: > James Coupe schrieb: > > them. Problem: if your shuffling is good enough, the original order > > doesn't matter, the outcome will be exactly as unpredictable regardless > > of where you start from. > > Agreed. What I would like to see is a tournament rule that gives a minimum > requirement for "good enough" shuffling. Most people are not math > geniuses (including me) so that would be really helpful. For a 90-card deck, 10 reasonably good riffle shuffles should be sufficient. You can read about what a riffle shuffle is here: http://en.wikipedia.org/wiki/Shuffling Here is a good article going into the math of one way to tell if you're shuffling well enough. It uses Magic: The Gathering as the example, but the same principles apply: http://www.starcitygames.com/php/news/article/4004.html Using that math for VTES, if you have a 90 card deck that has 17 Master cards in it, you should expect to draw two master cards in a row ~3.1 times in a sufficiently randomized deck. If you have 30 combat cards in a 90 card deck, you should expect to draw two combat cards in a row ~9.8 times in a sufficiently randomized deck, and 3 combat cards in a row ~3.1 times. So, if you want to check to see if your method of shuffling is sufficiently random, one way to check is to put all your master cards and combat cards on top, shuffle the way you usually do, and then check to see if you have a distribution close to what I list above. Of course, you'll need to do the experiment several times and take the averages, since randomness naturally has some variation. Ira

On Nov 17, 10:27 am, "Kevin M." <youw...@imaspammer.org> wrote: > Chris Berger <ark...@ugcs.caltech.edu> wrote: > > Salem <kella...@hotmail.com> wrote: > >>http://science.slashdot.org/article.pl?sid=08/11/14/1438252 > > >> "You may have heard that it takes about seven shuffles to mix up a > >> deck of cards to near randomness. Turns out, though, that most of > >> the time, perfect randomness is more than you need. In blackjack, > >> for example, you don't care about suits. The same mathematician who > >> developed the original result now says that for many games, four > >> shuffles is enough. And the result isn't only important for card > >> sharks. It helps reveal the math underlying Markov Chain Monte Carlo > >> simulations, telling applied mathematicians when they can stop their > >> simulations." > > >> would take a little adapting to vtes i guess. > > > I wonder how "good" the shuffles need to be. > > The definitive article:http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&i... > > Kevin M., Prince of Las Vegas > "Know your enemy, and know yourself; in one-thousand battles > you shall never be in peril." -- Sun Tzu, *The Art of War* > "Contentment... Complacency... Catastrophe!" -- Joseph Chevalier > Please visit VTESville daily!http://vtesville.myminicity.com/ > Las Vegas NAQ 2009http://members.cox.net/vtesinlv/- Hide quoted text - > > - Show quoted text - Hehehehehe. Nice answer. So for a deck of cards where n=90, what is the required number of riffle shuffles?

On Nov 17, 3:27 am, "Kevin M." <youw...@imaspammer.org> wrote: > Chris Berger <ark...@ugcs.caltech.edu> wrote: > > Salem <kella...@hotmail.com> wrote: > >>http://science.slashdot.org/article.pl?sid=08/11/14/1438252 > > >> "You may have heard that it takes about seven shuffles to mix up a > >> deck of cards to near randomness. Turns out, though, that most of > >> the time, perfect randomness is more than you need. In blackjack, > >> for example, you don't care about suits. The same mathematician who > >> developed the original result now says that for many games, four > >> shuffles is enough. And the result isn't only important for card > >> sharks. It helps reveal the math underlying Markov Chain Monte Carlo > >> simulations, telling applied mathematicians when they can stop their > >> simulations." > > >> would take a little adapting to vtes i guess. > > > I wonder how "good" the shuffles need to be. > > The definitive article:http://projecteuclid.org/DPubS/Repository/1.0/Disseminate?view=body&i... > Very interesting. Some of the math is beyond me, but I get the general gist. I don't think they mentioned anything about cutting or overhand-shuffling between riffles, which to me seems to be a given. Otherwise, the top card of the deck is going to, on average, move down about n/2 positions after shuffling n times, leaving the probability that the original top few cards are still in the top few after shuffling unnaturally high. If they mentioned it, it was in a section that I glossed over due to notation I didn't grok. Also, they don't specifically state a requirement for how "good" the shuffles have to be. They just state a formula for how people *do* shuffle (approximately, verified by experimentation). If I were able to shuffle "perfectly", i.e. split into two equal piles and then alternate one card from each pile without fail, that would screw things up quite a bit. I'm sure that doesn't really happen in practice though. As long as people shuffle fairly close to the probabilities they give, then I presume the conclusions hold up.

On Nov 17, 11:50 am, Chris Berger <ark...@ugcs.caltech.edu> wrote: > Very interesting. Some of the math is beyond me, but I get the > general gist. I don't think they mentioned anything about cutting or > overhand-shuffling between riffles, which to me seems to be a given. > Otherwise, the top card of the deck is going to, on average, move down > about n/2 positions after shuffling n times, leaving the probability > that the original top few cards are still in the top few after > shuffling unnaturally high. If they mentioned it, it was in a section > that I glossed over due to notation I didn't grok. I think the top card goes down closer to ~2^n positions, right? I mean, assume it goes either 0 or 1 position down on the first shuffle. Then (if it's still the top card) it goes down either 0 or 1 again, but if it's now in position 1 it's likely to go down 2-3 more positions (ending at position 3-4). And so on (ending at 0-1, 3-4, 8-9, or 11-12 on the third shuffle, which clearly doesn't average to position 1.5). -witness1

ira...@gmail.com > For a 90-card deck, 10 reasonably good riffle shuffles should be > sufficient. > > You can read about what a riffle shuffle is here: > http://en.wikipedia.org/wiki/Shuffling As a poker dealer, I do a lot of rifle shuffling, usually with 100% plastic cards. Let me tell you I'll never do it with collectible cards, not even in plastic sleeves. I want my cards to stay in good shape and this is definitely a way to hurt them. A lot. And a good deck costs a lot more than a pack of bicycle cards, doesn't it (as a matter of facts a deck of good non-plastic cards costs about the price of a booster, so you can afford to change it once in a poker night) ?! -------- Orpheus

[ quoted text not captured ] Yeah, I'm totally wrong on that n/2 comment. So you're probably right that it's closer to 2^n, which would mean after log2 k (k being number of cards in the deck) shuffles it could be anywhere, right? That changes things and more or less removes my one point of contention. I still plan to overhand shuffle in between riffles, because it still feels to me like the top of the deck isn't randomized enough otherwise, but I can see that it's more likely just a feeling than anything having to do with the mathematics.

[ quoted text not captured ] > anything having to do with the mathematics.- Hide quoted text - I'd say that's pretty reasonable. Most people don't have really really good shuffling, and my own breaks down at the top few cards occasionally. But if you did have really really good riffle shuffling (which is generally what mathematicians concern themselves with), you probably wouldn't need to do that. Likewise, pile shuffling is a pretty bad mechanism for randomization on its own, but it can separate cards that were stuck together and allow your normal randomisation techniques to work better. -witness1

Orpheus <orphe...@NOSPAMfree.fr> wrote: > ira...@gmail.com wrote: > For a 90-card deck, 10 reasonably good riffle > shuffles should be sufficient. >> >> You can read about what a riffle shuffle is here: >> http://en.wikipedia.org/wiki/Shuffling > > As a poker dealer, I do a lot of rifle shuffling, > usually with 100% plastic cards. > > Let me tell you I'll never do it with collectible cards, > not even in plastic sleeves. Especially since playing cards are single-cut printed cards, whereas CCG cards are mostly dual-layered (i.e. a two-card 'sandwich'). > I want my cards to stay in good shape and this is definitely a way to > hurt them. A lot. And a good deck costs a lot more than a pack of > bicycle cards, doesn't it (as a matter of facts a deck of good > non-plastic cards costs about the price of a booster, so you can > afford to change it once in a poker night) ?! I would disagree that riffle shuffling CCG cards hurts them "a lot", as I have been riffle shuffling MtG and VTES cards for literally decades and they are just beat around the corners, and very far from unplayable. Perhaps my riffle shuffle is more gentle than normal. Kevin M., Prince of Las Vegas "Know your enemy, and know yourself; in one-thousand battles you shall never be in peril." -- Sun Tzu, *The Art of War* "Contentment... Complacency... Catastrophe!" -- Joseph Chevalier [ quoted text not captured ]

Kevin M. wrote: > Orpheus <orphe...@NOSPAMfree.fr> wrote: >> ira...@gmail.com wrote: >> For a 90-card deck, 10 reasonably good riffle >> shuffles should be sufficient. >>> >>> You can read about what a riffle shuffle is here: >>> http://en.wikipedia.org/wiki/Shuffling >> >> As a poker dealer, I do a lot of rifle shuffling, >> usually with 100% plastic cards. >> >> Let me tell you I'll never do it with collectible cards, >> not even in plastic sleeves. > > Especially since playing cards are single-cut printed cards, whereas > CCG cards are mostly dual-layered (i.e. a two-card 'sandwich'). > >> I want my cards to stay in good shape and this is definitely a way to >> hurt them. A lot. And a good deck costs a lot more than a pack of >> bicycle cards, doesn't it (as a matter of facts a deck of good >> non-plastic cards costs about the price of a booster, so you can >> afford to change it once in a poker night) ?! > > I would disagree that riffle shuffling CCG cards hurts them "a lot", > as I have been riffle shuffling MtG and VTES cards for literally > decades and they are just beat around the corners, and very far from > unplayable. Perhaps my riffle shuffle is more gentle than normal. > > Kevin M., Prince of Las Vegas Perhaps, Kevin. But even the "bent around the corners" part doesn't bode well with me... Anyway, when you do have plastic sleeves, the lateral shuffle (don't know the real english name) is efficient enough. Or you can just make several rows and columns, rinse and repeat, and it works fine too. Orpheus -- "Cynicism isn't maturity. Callousness isn't strength. Pretending you don't care so you don't have to try isn't "winning" What you do with your life matters." Luther Manning.

Orpheus <orphe...@NOSPAMfree.fr> wrote: > Kevin M. wrote: >> Orpheus <orphe...@NOSPAMfree.fr> wrote: >>> ira...@gmail.com wrote: >>> For a 90-card deck, 10 reasonably good riffle >>> shuffles should be sufficient. >>>> >>>> You can read about what a riffle shuffle is here: >>>> http://en.wikipedia.org/wiki/Shuffling >>> >>> As a poker dealer, I do a lot of rifle shuffling, >>> usually with 100% plastic cards. >>> >>> Let me tell you I'll never do it with collectible cards, >>> not even in plastic sleeves. >> >> Especially since playing cards are single-cut printed cards, whereas >> CCG cards are mostly dual-layered (i.e. a two-card 'sandwich'). >> >>> I want my cards to stay in good shape and this is definitely a way >>> to hurt them. A lot. And a good deck costs a lot more than a pack of >>> bicycle cards, doesn't it (as a matter of facts a deck of good >>> non-plastic cards costs about the price of a booster, so you can >>> afford to change it once in a poker night) ?! >> >> I would disagree that riffle shuffling CCG cards hurts them "a lot", >> as I have been riffle shuffling MtG and VTES cards for literally >> decades and they are just beat around the corners, and very far from >> unplayable. Perhaps my riffle shuffle is more gentle than normal. > > Perhaps, Kevin. But even the "bent around the corners" part doesn't > bode well with me... In 15+ years of playing CCGs, I have never encountered "bent around the corners" cards. > Anyway, when you do have plastic sleeves, the lateral shuffle (don't > know the real english name) is efficient enough. Or you can just make > several rows and columns, rinse and repeat, and it works fine too. I have found anything other than brand-new sleeves near-impossible to shuffle and very user-unfriendly. I'd humbly suggest that if you believe your VTES cards will be devalued by shuffling them then you might be in need of some help. ;) Kevin M., Prince of Las Vegas [ quoted text not captured ]

On Nov 15, 9:48 am, Blooded Sand <sandm...@gmail.com> wrote: > So my original point was that I riffle shuffle 3 times, mixed > with 3 overhand shuffles. Is this not sufficient enough to > make it random? because at a certain point, more shuffling > will actually result in a less random result. Strange, but true. > All i want to do is start from a sufficiently homogenized > position, and then shuffle. Players generally prefer even distribution of cards. However, as LSJ pointed out, a random result need not be the same as an even result. It is actually surprising the extent to which clumping tends to occur in random results. I have a vague recollection of players complaining about the results obtained by the computerized shuffler on JOL. The difference was, of course, that the JOL shuffler was truly random -- unlike their own usual efforts. An illustration of this is the famous birthday problem. Put 23 people together, and it is more than 50% likely that 2 or more will share the same birthday. Put 57 people together, and it is more than 99% likely, and there will probably be multiple pairings. An "even distribution", would result in everyone having birthdays 6 or 7 days apart, but such a result is astronomically unlikley. > Why is this any different from > taking your deck after play and making sure there are > no clumps? Deliberate unclumping is cheating, unless you shuffle sufficiently afterwards to ensure normal chances of re-clumping. I am sure a certain amount of unconscious "cheating" often occurs. For instance, if a player is satisifed with the even distribution of his cards in the first round of a tournament, he may decide that his deck is already well "randomized" and give it only the most cursory of shuffles going into the second round. If, however, he runs into clumping in his first round, he is more likely to do a vigorous shuffle before the second round.

On Nov 15, 11:32 am, LSJ <vtes...@white-wolf.com> wrote: > This false perception comes from a common > misunderstanding of what "random" is. Random doesn't > mean that the various categories of cards in the deck will > be uniformly distributed through the deck. It means that > each possible ordering of the deck, including the ones in > which each group of cards in the various > categories are clumped together, is equally likely. I suspect such misperceptions are less common among poker players. When they are dealt a hand of 4 aces, they are less likely to curse a bad shuffle, and more likely to sing the praises of Lady Luck.

>>> I would disagree that riffle shuffling CCG cards hurts them "a lot", >>> as I have been riffle shuffling MtG and VTES cards for literally >>> decades and they are just beat around the corners, and very far from >>> unplayable. Perhaps my riffle shuffle is more gentle than normal. >> >> Perhaps, Kevin. But even the "bent around the corners" part doesn't >> bode well with me... > > In 15+ years of playing CCGs, I have never encountered "bent around > the corners" cards. "Beat" is the word you used. Thank you to point out that english is you first language and not mine. That was useful. >> Anyway, when you do have plastic sleeves, the lateral shuffle (don't >> know the real english name) is efficient enough. Or you can just make >> several rows and columns, rinse and repeat, and it works fine too. > > I have found anything other than brand-new sleeves near-impossible to > shuffle and very user-unfriendly. Depends on the sleeves, and how you shuffle them. Some are bad, yes. It's also a business so you can buy new ones from time to time. Better than ruining my cards anyday. > I'd humbly suggest that if you believe your VTES cards will be > devalued by shuffling them then you might be in need of some help. ;) Such humility forces one's admiration. So you don't care in which condition the cards you get are, and it has no influence over the price you pay for them ? Good for you. Cards can be ruined by too much bad shuffling, that's a fact. No help needed, thanks. Anyway I don't care that much about the "value", I just like my cards mint or close enough. And preferably flat (riffle shuffles tend to bend the cards). -- [ quoted text not captured ]

"Kevin M." <you...@imaspammer.org> wrote in message news:gfsltu$ia1$1...@aioe.org... > I have found anything other than brand-new sleeves near-impossible to > shuffle and very user-unfriendly. Cut cards a few times, pile shuffle, cut cards a few times, pile shuffle, cut cards a few time. This creates total randomness, as verified by the fact that I can easily get totally screwed by card clumping, insanely bad distributions, and other forms of deranged ordering. Whether I started from a perfectly sorted deck or a carefully weaved one, doesn't matter. It works. The main downside (assuming you're not trying to cheat, of course) is that it takes a bit of time. Opponents and judges tend to get impatient. If I have time between games, I try to do at least one of the pile shuffles ahead of time. Fred

On Nov 15, 1:05 pm, Chris Berger <ark...@ugcs.caltech.edu> wrote: > On Nov 15, 11:32 am, LSJ <vtes...@white-wolf.com> wrote: > > > If I take those > > > cards I played during the game and put them in pseudo-random spots in > > > the deck instead of just stacking them on top, I believe that it would > > > take still fewer shuffles to sufficiently randomize. > > > Nah, since you know the positions of those insertions as well as the distance > > between those various insertions. > > But you don't know the exact position of the insertions any better > than if you overhand shuffled. Theoretically, when you overhand > shuffle, you "know" that the top, say, 15 cards are now the bottom 15, > the next 27 are now the next 27 from the bottom, etc... If you don't > count where you insert the cards into the deck, and assuming you > insert them face down without looking at them, it's very close to > random. Suppose the 7 cards you know about include a Fame and a Bum's Rush. These are cards that work well together, and ideally you would like to see them together. After inserting, you need to shuffle them enough so there is the normal chance that this will occur. If, after insterting, you KNOW that the Fame and the Bum's Rush are NOT side by side (or that they ARE side by side) then the result is not random. Still, I'm not sure its entirely wrong to say that the less you know about the contents of a deck, the less shuffling you need do to completely lose track of what you know. For instance, if you have seen only one card, the only thing you need do is place it back in the deck, and then cut the deck enough times so that you have no clue as to where that card is.

On Nov 18, 3:48 pm, jwjbwhe...@gmail.com wrote: > Still, I'm not sure its entirely wrong to say that the less you know > about the contents of a deck, the less shuffling you need do to > completely lose track of what you know. For instance, if you have > seen only one card, the only thing you need do is place it back in the > deck, and then cut the deck enough times so that you have no clue as > to where that card is. Eliminating your knowledge of the order is not the same as randomizing the order. -witness1

[ quoted text not captured ] In the ultimate scheme of things, there is no such thing as random. No matter how much I shuffle, God will always know the order the cards are in, and will know precisely how I put them in that order. But it suffices if I find a method to make sure that every mortal concerned (not just me) has no basis for knowing or guessing the order of the cards. Eliminating all relevant knowledge is the key. If I shuffle a "deck" of only 3 cards, it will be impossible to shuffle successfully unless I allow myself to lose track of which card is which.

[ quoted text not captured ] This is not actually correct. If I sort my deck alphabetically, and stick it in a box, and pull it out a month later, the mere fact that I've forgotten that I sorted the deck does not mean it's sufficiently randomized. Knowledge of the deck's order is unrelated to whether the deck is randomized. The key is that no matter what order it started in, the randomization method could result in any of the n! possible orderings with (approximately) equal probability. -witness1

[ quoted text not captured ] In that case, your method has failed to achieve the stated goal. As soon as you start drawing cards, you and everyone else at the table will have a basis for guessing the order of the remaining cards. It will be an observable fact that the cards drawn so far are in alphabetical order. > Knowledge of the deck's order is unrelated to whether the deck is > randomized. Lack of any basis for knowledge or guesswork is the sole basis for "random". > The key is that no matter what order it started in, the > randomization method could result in any of the n! possible orderings > with (approximately) equal probability. Lack of knowledge is the basis for equal "probability". If the only information I have about the seven horses, in a horserace, are their names, then, from my point of view, each horse is equally likely to win.