Originally posted by Lyle Waldman:

What's the philosophy behind this? We all know that it will happen eventually, and we can deterministically define such a game state where it happens, so what's at issue here?

Another problem besides what has been stated so far is this: even if we are (virtually) guaranteed to reach the desired game state, if we cannot deterministically describe the loop, we cannot know all the intermediate game states that we will go through on the way to the desired outcome. So if we allow this sort of shortcut, what will happen when the Four Horsemen's opponent wants to interrupt the shortcut with Tormod's Crypt? Can he specify a certain game state in which, if and/or once reached, he wants to activate the Crypt (such as, for example, Emrakul and Blasting Station in the graveyard, with Emrakul's shuffle trigger on the stack)? How can we determine if the loop player's desired outcome or the opponent's desired interruption game state occurs first? Or should the opponent be able force the loop player to manually play through each iteration in this case to see if a game state in which he wants to interrupt just happens to come up?

Since I don't know how to multiquote, I'll just reply by name and hopefully everything works out.

@Sebastian: The opponent is free to say “I want to respond at some point, so please execute the loop manually”. This is true for any loop, not just loops of this kind. By this method, the opponent can determine if the required game state occurs. However, we only allow this interruption in a game state where the opponent actually does have a legitimate reason to interrupt; if the opponent is just disagreeing to the shortcut to be a jerk and take additional match time, we do not allow this.

@Charlotte: Define “never”. Given infinite time, it will eventually happen. Do we want a Magic game to be decided based on the inevitability of the heat death of the universe? I'm pretty sure that requires a degree in Physics much more advanced than any degree in Mathematics required by the statistical formulation of the problem.

@Mark, Paul, Shawn: If that's the philosophy, then fine. My personal opinion is that the argument is relatively simple and thus should be allowed. Here's a very short formulation of the proof that anyone should be able to understand, assuming they understand the notion of being “random” (which I presume all players should understand; if there's a player who doesn't understand the notion of “random”, then we have a bigger problem):

We assume the deck is random after each shuffle. As a result, for any posiiton in the deck, there is a non-zero chance of Emrakul being in the deck at that position after each shuffle. All we want is that Emrakul is at the bottom. Since Emrakul can be anywhere, Emrakul can be at the bottom. Thus eventually Emrakul will be at the bottom, and then the required game state occurs.

Sure, we gloss over the exact definition of “eventually” and push some probabalistic things under the rug, but this seems like an argument that pretty much anyone should be able to understand and agree with. Of course, the argument is different for Legacy since graveyard order matters; again, in Legacy, I agree that this shortcut can't be used at all.

Originally posted by Lyle Waldman:

@Sebastian: The opponent is free to say “I want to respond at some point, so please execute the loop manually”. This is true for any loop, not just loops of this kind. By this method, the opponent can determine if the required game state occurs. However, we only allow this interruption in a game state where the opponent actually does have a legitimate reason to interrupt; if the opponent is just disagreeing to the shortcut to be a jerk and take additional match time, we do not allow this.

Then where do we draw the line on how many iterations is acceptable for pace of play reasons? If Player A is executing the loop and trying to get to a certain gamestate, and Player B is waiting for a particular gamestate to interject with his Tormod's Crypt, how long are we willing to let them stare at each other and execute the loop before we ask them to move on in the game? That's precisely why the exact number of iterations needs to be expressed by the player executing the loop - otherwise both players could be sitting there doing that for the rest of the round instead of playing Magic.

Originally posted by Casey Brefka:

Lyle Waldman
@Sebastian: The opponent is free to say “I want to respond at some point, so please execute the loop manually”. This is true for any loop, not just loops of this kind. By this method, the opponent can determine if the required game state occurs. However, we only allow this interruption in a game state where the opponent actually does have a legitimate reason to interrupt; if the opponent is just disagreeing to the shortcut to be a jerk and take additional match time, we do not allow this.

Then where do we draw the line on how many iterations is acceptable for pace of play reasons? If Player A is executing the loop and trying to get to a certain gamestate, and Player B is waiting for a particular gamestate to interject with his Tormod's Crypt, how long are we willing to let them stare at each other and execute the loop before we ask them to move on in the game? That's precisely why the exact number of iterations needs to be expressed by the player executing the loop - otherwise both players could be sitting there doing that for the rest of the round instead of playing Magic.

I do have a well-thought-out response to that question, but I've been recommended not to try to argue alternative policies in public on this forum, so I'm going to end this thread of discussion without answering this question, unfortunately. If you'd like a real response to that question, we can take it to PM.

While the judge-l archives are possibly not accessible any more or not by all, but we have had these discussions an awful lot over time and they have all deteriorated into not very useful areas of discussion so I am going to close this thread. There have been sufficient answers explaining policy and why policy is as it is.