partial deck shuffling acceptable?

garbageaggro

But Jaco's shuffle already presumed the deck is sufficiently randomized.

Khahan

@joshuabrooks If you look at the link @JACO posted it explains that the requirement is to discourage cheating.

From a mathematical perspective, I'm not sure why JACO's shuffle is allowed, if the intent of the rule is to discourage cheating. They explicitly say cutting is not sufficient in JACO's link. If I were in charge, I would only allow shuffles which, if performed sufficiently many times, converge to the uniform distribution. JACO's shuffle will never do that. Cutting your opponent's deck at a random location would, although the convergence is incredibly slow. Alas, mathematicians are not in charge of the DCI.

I'm 100% sure why JACO's shuffle is allowed - because its an FNM event which has the REL as our proxie tournaments and in that level REL simple cuts all the up to full shuffles are legal to do.

JACO

It's as simple as this: if your opponent has sufficiently randomized their deck as they are required to do so before presenting to you, and you further randomize it so no cards are known, it's still randomized. There is not going to be some Magic formula for how much of the deck to shuffle how many times to further randomize it if they have already done so. It is either randomized so no card locations are known, or it is not. If you cannot wrap your head around that you do not understand the purpose of the rules.

diophan

@JACO It says in the forum you linked to that the purpose of the rule is to discourage cheating at competitive+ REL. Even in vintage there are instances of people who take advantage of the casual/good natured mentality of the format by using shuffling cheats.

Your shuffling technique does not do that. I understand perfectly well that a distribution approximating the uniform distribution does not need to have a transformation applied to it which would bring a non-uniform distribution to uniform.

@Khahan JACO said he's used this at GPs.

@JACO

It's about a bigger picture, called "Tournamnet Integrity."

While you may not be gaining an advantage by doing this in a competative tournamnet, your opponent could cheat by stacking their deck with cards that aren't good in the matchup on the bottom part of their deck. Then you, doing your half shuffle, are not randomizing their deck and are essentially helping your opponent cheat. You are facilitating their cheating, which not only hurts you, but allows for a player with less integrity advancing in the tournamnet, an overall loss for all the players who play by the rules.

If I know how you are going to shuffle, I can cheat you. By definition, you are not acting randomly, you are acting deliberatly and that allows for cheating. Which ruins the tournaments integrity.

You are making an assumption that you're opponents deck is randomized. For tournament integrity, you must make sure it is randomized.

It's a matter of ethics. Your half shuffle is an unethical shuffle. Please shuffle properly, for everyone else in the tournament. Forget about how it affects you and your opponent only, each match matters in a tournament. Please give it as much reverence as it deserves.

JACO

@gkraigher said:

@JACO

It's about a bigger picture, called "Tournamnet Integrity."

While you may not be gaining an advantage by doing this in a competative tournamnet, your opponent could cheat by stacking their deck with cards that aren't good in the matchup on the bottom part of their deck. Then you, doing your half shuffle, are not randomizing their deck and are essentially helping your opponent cheat. You are facilitating their cheating, which not only hurts you, but allows for a player with less integrity advancing in the tournamnet, an overall loss for all the players who play by the rules.

If I know how you are going to shuffle, I can cheat you. By definition, you are not acting randomly, you are acting deliberatly and that allows for cheating. Which ruins the tournaments integrity.

You are making an assumption that you're opponents deck is randomized. For tournament integrity, you must make sure it is randomized.

It's a matter of ethics. Your half shuffle is an unethical shuffle. Please shuffle properly, for everyone else in the tournament. Forget about how it affects you and your opponent only, each match matters in a tournament. Please give it as much reverence as it deserves.

Greg, I await your next post, where I am indicted for helping facilitate the wars in Iraq and Afghanistan, because I did not explicitly vote for Al Gore, and against George Bush (/sarcasm). At no point do you know how I'm going to shuffle, because I don't know how I'm going to shuffle each time - which is part of the point. I don't just grab half the deck every time. Sometimes I grab the full deck and count my opponent's card and then shuffle part of it, sometimes I grab the top 30 cards, sometimes I grab the top 58 cards, sometimes I grab the top 15 cards and shuffle repeatedly, and sometimes cut after that (again, random, and unpredictable). The point is it is random, in line with the rules, and entirely to help prevent shuffle hacks. It is much more difficult to hack someone when you do not know how they will randomize or manipulate your deck afterwards. I expect my opponent to sufficiently randomize their deck, and watch my opponent shuffle, and if I feel they do not present a sufficiently randomized deck at any point I'm going to ask them to shuffle more, and if they refuse, I will call a judge (which is exactly what the rules allude to).

@diophan said:

@JACO It says in the forum you linked to that the purpose of the rule is to discourage cheating at competitive+ REL. Even in vintage there are instances of people who take advantage of the casual/good natured mentality of the format by using shuffling cheats.

Your shuffling technique does not do that. I understand perfectly well that a distribution approximating the uniform distribution does not need to have a transformation applied to it which would bring a non-uniform distribution to uniform.

Ryan, understood about the Competitive + Professional REL differences (and those that seek to manipulate the tournament gaming experience at any level), and my actions are definitely done with that explicitly in mind. As I mentioned above, at every level (FNM, GP, etc.) I watch my opponent shuffle each time, and if I feel they have not sufficiently randomized the deck I will ask them to shuffle a bit more before they even present. I try to practice and play with Competitive REL mindset as well, so the routine each time I play cards is the same, and so my opponent can expect a good baseline of courtesy and professionalism. Whatever I do on top, which I do not plan ahead of time, is merely randomizing a randomized deck exclusively to prevent any shuffle hacks my opponent may be using that I'm missing (which is why you should never just simply cut a deck, because no matter how vigilant you remain, you will not catch everything). A good parallel to this is "trust, but verify."

@JACO

Now you are being ridiculous. The rules are in place for a reason, sometimes you might know why they are, other times you don't.

You've acknowledged that you understand the comprehensive rules, so not playing by those rules is no longer a matter of ignorance, but of ethics.

There's a great situation that comes up a lot: you have chains of Mephistopheles (a replacement effect) and your opponent casts brainstorm.

An unethical player, ignorant to the rules, might try to allow their opponent to forget the replacement effect, creating an invalid game state where you get to look at their hand and make them discard a card for having an extra card in hand.

In reality, if you knowingly allowed this to happen, you are the player cheating...not your opponent.

A judge would investigate and determine what to happen, both players would get a warning, but you could get a DQ for knowingly not following the rules.

There are rules to this game. It's not a manner of do I want to play by the rules this time or not, or how much of not playing by the rules can I get away with. Play by the rules.

Aelien

On a related matter: If you cast Mind's Desire do you shuffle and present your deck to cut before every reveal, do you just shuffle once at the beginning, and then if it becomes relevant or do you just shuffle and then cut/minor shuffle before every following reveal? I have seen everything mentioned practiced before.

@JACO I find this conversation interesting and wish to clarify that I am not trying to insinuate anything. A concern I would have is if you are watching the opponent shuffle and you see the bottom card (or really any card) of their deck, your shuffle no longer serves to randomize the deck. Even if the card is in the shuffled portion of the deck, you are aware of this fact and therefore have some knowledge of the deck's order. How do you approach or have you approached such situations?

10drills

I just don't understand how you translate "your opponent's deck" to mean "however many cards from your opponent's deck you feel like picking up that day." But I guess we all interpret things differently.

GrandpaBelcher

https://www.youtube.com/watch?v=dzMZkT8WIJQ

JACO

@gkraigher apologies in advance if this seems combative, you are talking about two different things. Allowing an illegal game state and then trying to scum your opponent for advantage is still illegal, and trying to stretch this to that is unwise. Aside from a few fallacious claims you have done nothing to dispel the notion that randomly shuffling a randomized deck is illegal. There is nothing in the IPG, Tournament Rules, Judges Wiki, etc. on exactly how to shuffle your opponent's deck after they present (other than not to pile shuffle beyond once, because it's not sufficiently randomizing), intentionally. The onus is on the original player to sufficiently randomize their deck before presenting, every time, and the penalties and remedies presented are specifically on them as well. There are plenty of ways to get to a sufficiently randomized deck before presenting to your opponent, which is part of the reason why it is not more explicitly outlined. It is then a binary. Is it sufficiently randomized? Yes, or no. If yes, present to your opponent. If not, randomize further, and then repeat the question and proceed.

You then pick up the sufficiently randomized deck as presented, and whether you shuffle it 1 or 100 times, it is still sufficiently randomized. It is still a binary. Sufficiently randomized, or not. Judges are not going to sit at every table to legislate how many times you shuffle at this point, how many times you do an overhand shuffle to what percentage of the cards, how many times you do a perfect side shuffle to what percentage of the cards, and so on. It is still in a binary - sufficiently randomized, or not. The reason we do it again after being presented, in whatever method we do, is solely to prevent cheating, as I have already stated, and in line with the intent of the rules. Trust, but verify.

@ChubbyRain said:

@JACO I find this conversation interesting and wish to clarify that I am not trying to insinuate anything. A concern I would have is if you are watching the opponent shuffle and you see the bottom card (or really any card) of their deck, your shuffle no longer serves to randomize the deck. Even if the card is in the shuffled portion of the deck, you are aware of this fact and therefore have some knowledge of the deck's order. How do you approach or have you approached such situations?

That's a good question for anybody, and one which is not addressed by anybody else here (because you can manipulate the deck with dozens of shuffles and still keep X cards toward the bottom, reducing the chance they will be drawn). At any point, if you or your opponent become aware of the location of contents of a single or more card that is supposed to be randomized in the deck while they present, it is no longer sufficiently randomized, and they need to randomize further. You should immediately ask your opponent to shuffle with their cards face down and away so as to not reveal this. I doubt a majority of people do that, because they think they can use the information, but that is neither legal nor sporting. I have definitely told my opponent I have seen their Tinker or Ancestral on the bottom of the deck because of their shuffling, and told them to shuffle more face down before presenting. I have also watched plenty of opponents look at their own decks while side shuffling, and asked them to stop, because it is not even close to random. Frankly, I just don't think a lot of Magic players (or people in this thread) understand what "sufficiently randomized" means.

10drills

@JACO I mentioned potentially seeing their cards already, yesterday. You speak as though you would tell your opponent to shuffle in a different manner, but you fail to realize that if you don't tell them that, how are they to know whether or not you saw something once you've chosen to randomize their deck in a suspicious manner? If you did not say anything to me, I'm going to assume you're doing it that way for a reason, and probably one I should be calling a judge for. None of your arguments make sense to me. You continue to defend this method based on the deck already being sufficiently randomized, but there are a lot of factors involved outside of the mathematical ones that make this seem EXTREMELY shady. I don't think there's any world where you're going to convince me this is perfectly okay.

Khahan

@SeanOhh said:

@JACO I mentioned potentially seeing their cards already, yesterday. You speak as though you would tell your opponent to shuffle in a different manner, but you fail to realize that if you don't tell them that, how are they to know whether or not you saw something once you've chosen to randomize their deck in a suspicious manner? If you did not say anything to me, I'm going to assume you're doing it that way for a reason, and probably one I should be calling a judge for. None of your arguments make sense to me. You continue to defend this method based on the deck already being sufficiently randomized, but there are a lot of factors involved outside of the mathematical ones that make this seem EXTREMELY shady. I don't think there's any world where you're going to convince me this is perfectly okay.

Its only shady if you are a shady person who thinks this way. Sorry, but that's the way I see it. If you are honest and don't look for ways to cheat the system to begin with - none of the arguments being made against JACO hold any water at all. JACO flat out stated if he sees a card or something happens that the deck is not sufficiently randomized he'll ask his opponent shuffle in a different way.

I'm going to be blunt here - the arguments being made against his method are simply ridiculousness from over-thinking or over-analyzing the situation. I applaud JACO for taking the time to have a discussion about and explain it - but nothing he can say will suffice, ever. Because the arguments he is trying to counter are so hypothetical and situational that the people making them can just make them over and over with little tweaks, little things added, come from a different angle or just ignore what JACO or anybody else has said.

You get a deck from an opponent, it is randomized. If you don't feel its randomized, you either call a judge if think there is something underhanded going on or you ask your opponent to shuffle a bit more. Once that is done and you are satisfied it is truly random, you could pile shuffle, riffle shuffle, cut in half, play 52 (or 60) card pick up, shuffle 1/3, 1/2 or 1/10 of the deck or take the top card and put it on the bottom - as long you do nothing to try and gain knowledge of any particular card position its still random. There is no facilitating a cheater. There is no side stepping the rules. Can we please stop making stuff up for the sake of having a discussion? There is absolutely nothing in JACO's post to justify a few people piling on insinuating he's a cheater.

10drills

@Khahan this is extremely naive. I'm not targeting him specifically, I don't know him personally but I do know of him. But to just flat out trust everyone is ridiculous. My position on the matter comes from having seen cheaters cheat. You never know who it's going to be. I've had a person I would consider a friend attempt to cheat. I just won't let it happen to me if at all possible. Nobody should be doing anything that could be conceived as cheating, even if it's completely on the up and up. I'm just making the argument that this could EASILY be seen as cheating, so it shouldn't be done, nor should it be allowed.

@Khahan

I don't think Jaco is a cheater. I'd never say that because he is not, my argument is rather different:

Jaco is lazily not shuffling his opponents decks in every situation where he should.
this creates an environment where cheaters could take advantage of the situation.
if someone was able to cheat Jaco, the integrity of the entire tournament is compromised.
therefore, lazily shuffling creates an environment where cheaters could flourish, so knowingly allowing this in competitive play is unethical.

JACO

@SeanOhh said:

@JACO I mentioned potentially seeing their cards already, yesterday. You speak as though you would tell your opponent to shuffle in a different manner, but you fail to realize that if you don't tell them that, how are they to know whether or not you saw something once you've chosen to randomize their deck in a suspicious manner? If you did not say anything to me, I'm going to assume you're doing it that way for a reason, and probably one I should be calling a judge for. None of your arguments make sense to me. You continue to defend this method based on the deck already being sufficiently randomized, but there are a lot of factors involved outside of the mathematical ones that make this seem EXTREMELY shady. I don't think there's any world where you're going to convince me this is perfectly okay.

You have the right attitude, and should always remain vigilant, as I said above. But the scenarios you are concerned about are the same no matter how your opponent shuffles after you have presented, whether you realize it or not, so this is kind of irrelevant (it's a matter of honesty if cards are accidentally revealed and one player does not realize it, because there is no way for a judge to know/enforce what you may have seen or not seen). If they see your Ancestral Recall on the bottom as you shuffle or present your deck, and they say nothing, and then side shuffle and overhand shuffle the "full deck" 100 times, it is still quite easy to keep that Ancestral Recall on the bottom of the deck, without you knowing whether or not they saw anything. I'd be happy to demonstrate that for anybody who wishes to see in person. Either the deck is sufficiently randomized, or it is not. If either player knows the location of one or more cards after shuffling it is not sufficiently randomized. End of story. The onus is on the player shuffling their deck to sufficiently randomize it, and then whoever is presented the deck basically does whatever anti-cheat shuffling measures are appropriate. Best practice in any case is to shuffle with card face down and away from both players, whether you are talking about your own deck or your opponent's deck. Owen Turtenwald does a pretty good job of this if anybody is seeking video of what I mean (which I've tried to get better at myself over the years). This is not hard.

10drills

@JACO Believe it or not, I do understand what you're saying. But to me, the way you do it is just a more blatant version of the same thing. Not a "if you did it right, this is fine" situation. It's almost like you just want to show off some randomization knowledge at any chance you get (which by all means, go for it, I'll still call a judge).

FirstLevelMagic

@diophan said:

Cutting your opponent's deck at a random location would, although the convergence is incredibly slow.

You nerd sniped me with this and I went off to calculate how many cuts it would take - and it turns out you will never approach randomization, at least, not with a single-point cut, as successively cutting a deck of N cards at a single point can only result in N possible permutations of the deck, independent of the number of cuts, not N! permutations. You're basically just moving which card is the top without changing the card order at all (or, alternatively, it's like you're pointing at a wheel of cards, in some order, and the random cut just changes what card in the wheel you're pointing at).

@Evoclipse For mind's desire resolution in paper I've always asked my opponent what they want to do while I'm shuffling. I've never had an opponent want a full shuffle between each flip, it's always been either 'flip them until it matters' or 'cut between each flip'.

@JACO if OP asked you to just shuffle the whole deck when paired, would you? That seems like a sane solution to me. Edit: I met you at champs last year, although I doubt you'd remember me as it was pretty quick, but the impression I got then made me wonder if OP even reasonably asked.

rikter

I honest to god cant believe that this is STILL going on, or that @JACO hasnt thrown his hands in the air and just stopped.

I dont know what the hell Jaco did to OP, but my experiences with him, and Im sure many others, are overwhelmingly positive. If he wants to scoop to him, let him.

Have we beaten this dead horse to a pulp yet?