Pool Hopping: The SIMPLE Solution! - page 2.

NickW

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Quote from: JoelKatz on July 13, 2011, 09:31:22 AM

Quote from: NickW on July 13, 2011, 09:26:31 AM

Defining in terms of time rather than shares is absolutely fine provided the period is long for the smaller pools.

It can be in shares or time. If the window contains more shares, it will likely also contain more found blocks, but they will be divided over the greater shares. The expected revenue per share will be precisely the same, and that's all that's needed.

If a time window has n shares and m blocks, the payout per share will be 50m/n. If later that time window has 2n shares submitted, it will be expected to find twice as many blocks. The payout will be 50(2m)/(2n) which is precisely the same.

I understand this completely. The reason smaller pools should have a longer window is to reduce variance. Non 24-7 miners in small pools with a small window (relative to average time to find a block) are going to have payouts all over the place.

Meni Rosenfeld

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Quote from: JoelKatz on July 13, 2011, 09:42:15 AM

Quote from: Meni Rosenfeld on July 13, 2011, 09:32:37 AM

Quote from: JoelKatz on July 13, 2011, 09:24:53 AM

Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

In a nutshell, if an SMPPS pool with no fees runs long enough, with probability 1 it will eventually reach a point of such unluckiness that its payouts will be miniscule. Miners will leave and the pool will never recover. At that payment miners with pending payments will never receive them.

I don't understand why you say this. With SMPPS, every submitted share has precisely the same expected payout regardless of the past performance of the pool.

Only if you assume people are willing to wait arbitrarily long for their rewards.

They don't have to wait arbitrarily long. They only have to wait until the SMPPS pool accumulates whatever the number of shares chosen for N is. At that point, they will get whatever payment their share is going to generate.

Quote

The lower the pool's current balance, the longer it will take to get the full payout, and people will lose patience. Add to this the fact that people will fear the collapse of the pool, a self-fulfilling prophecy which will prevent ever getting the payment. When the pool is in the red, massive abandonment is a schelling focal point.

I don't follow you. What do you mean by the "pool's current balance"?

The way a SMPPS pool works is this: People submit shares to the pool. The pool tries to find blocks. When it finds a block, it pays out on each of the N shares received prior to finding that block, paying 50/N bitcoins. N can be chosen large enough so that most shares pay out.

You do have to wait until the pool finds a block to get paid though. So this won't work very well for very small pools. But once a pool is large enough to find a block at least once a day, there's no reason to think it would shrink.

You're talking about PPLNS. I was talking about SMPPS. PPLNS is a great method as I've mentioned here and elsewhere.

Quote from: JoelKatz on July 13, 2011, 09:43:03 AM

Quote from: Meni Rosenfeld on July 13, 2011, 09:40:16 AM

No, it will make the pool vulnerable to hopping based on pool hashrate fluctuations. It is more profitable to mine for the pool when the current hashrate is higher than the average over the current window.

No it won't. When the hashrate is higher, the number of shares per window will be higher, resulting in lower payouts per block found. Of course more block will be found, equaling things out perfectly.

Read carefully. I said "current hashrate > average hash rate over the window". The number of shares per window depends on the average hashrate over the window, not the current hashrate. Meanwhile, the chance your share will be included in a payout does depend on the current hashrate.

JoelKatz

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Quote from: Meni Rosenfeld on July 13, 2011, 09:40:16 AM

No, it will make the pool vulnerable to hopping based on pool hashrate fluctuations. It is more profitable to mine for the pool when the current hashrate is higher than the average over the current window.

No it won't. When the hashrate is higher, the number of shares per window will be higher, resulting in lower payouts per block found. Of course more block will be found, equaling things out perfectly.

JoelKatz

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Democracy is vulnerable to a 51% attack.

Quote from: Meni Rosenfeld on July 13, 2011, 09:32:37 AM

Quote from: JoelKatz on July 13, 2011, 09:24:53 AM

Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

In a nutshell, if an SMPPS pool with no fees runs long enough, with probability 1 it will eventually reach a point of such unluckiness that its payouts will be miniscule. Miners will leave and the pool will never recover. At that payment miners with pending payments will never receive them.

I don't understand why you say this. With SMPPS, every submitted share has precisely the same expected payout regardless of the past performance of the pool.

Only if you assume people are willing to wait arbitrarily long for their rewards.

They don't have to wait arbitrarily long. They only have to wait until the SMPPS pool accumulates whatever the number of shares chosen for N is. At that point, they will get whatever payment their share is going to generate.

Quote

The lower the pool's current balance, the longer it will take to get the full payout, and people will lose patience. Add to this the fact that people will fear the collapse of the pool, a self-fulfilling prophecy which will prevent ever getting the payment. When the pool is in the red, massive abandonment is a schelling focal point.

I don't follow you. What do you mean by the "pool's current balance"?

The way a SMPPS pool works is this: People submit shares to the pool. The pool tries to find blocks. When it finds a block, it pays out on each of the N shares received prior to finding that block, paying 50/N bitcoins. N can be chosen large enough so that most shares pay out.

You do have to wait until the pool finds a block to get paid though. So this won't work very well for very small pools. But once a pool is large enough to find a block at least once a day, there's no reason to think it would shrink.

Meni Rosenfeld

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Quote from: NickW on July 13, 2011, 09:26:31 AM

Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

Quote from: NickW on July 13, 2011, 08:09:56 AM

Correct me if I'm wrong, but I believe crossing pool boundaries would mean the "window" could be as long as you wanted. Even 24 hours.

First, defining the window in terms of units of time is bad. You need to define it in terms of number of shares.

But yes, I guess in the multiple-payment variant, you could make the window long. But this will also mean you'll have to make sure you're handling difficulty changes properly.

In the single-payment variant, the window must be less than the difficulty by some margin.

Defining in terms of time rather than shares is absolutely fine

No, it will make the pool vulnerable to hopping based on pool hashrate fluctuations. It is more profitable to mine for the pool when the current hashrate is higher than the average over the current window.

Meni Rosenfeld

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Quote from: JoelKatz on July 13, 2011, 09:24:53 AM

Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

In a nutshell, if an SMPPS pool with no fees runs long enough, with probability 1 it will eventually reach a point of such unluckiness that its payouts will be miniscule. Miners will leave and the pool will never recover. At that payment miners with pending payments will never receive them.

I don't understand why you say this. With SMPPS, every submitted share has precisely the same expected payout regardless of the past performance of the pool.

Only if you assume people are willing to wait arbitrarily long for their rewards. The lower the pool's current balance, the longer it will take to get the full payout, and people will lose patience. Add to this the fact that people will fear the collapse of the pool, a self-fulfilling prophecy which will prevent ever getting the payment. When the pool is in the red, massive abandonment is a schelling focal point.

JoelKatz

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Democracy is vulnerable to a 51% attack.

Quote from: NickW on July 13, 2011, 09:26:31 AM

Defining in terms of time rather than shares is absolutely fine provided the period is long for the smaller pools.

It can be in shares or time. If the window contains more shares, it will likely also contain more found blocks, but they will be divided over the greater shares. The expected revenue per share will be precisely the same, and that's all that's needed.

If a time window has n shares and m blocks, the payout per share will be 50m/n. If later that time window has 2n shares submitted, it will be expected to find twice as many blocks. The payout will be 50(2m)/(2n) which is precisely the same.

NickW

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Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

Quote from: NickW on July 13, 2011, 08:09:56 AM

Correct me if I'm wrong, but I believe crossing pool boundaries would mean the "window" could be as long as you wanted. Even 24 hours.

First, defining the window in terms of units of time is bad. You need to define it in terms of number of shares.

But yes, I guess in the multiple-payment variant, you could make the window long. But this will also mean you'll have to make sure you're handling difficulty changes properly.

In the single-payment variant, the window must be less than the difficulty by some margin.

Defining in terms of time rather than shares is absolutely fine provided the period is long for the smaller pools. It also means it's always constant (in time) even when the hash rate of the pool fluctuates. A window which is always constant and defined by time makes it much simpler for the average miner to understand. Payments are not calculated by a miner's proportional time in a pool, but by the proportion of the shares they submitted in the window to the total number of shares in the window. The Window still slides with the discovery of a new block in that pool.

Yes, it would have to involve calculating payment from the same shares more than once if blocks are found over a much shorter period than the window. I'd think it may even be best to have a window longer than the expected time to find a block to decrease payout variance. You would not have to make any adjustments for difficulty changes.

I don't see a single-payment variant working well with this method.

JoelKatz

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Democracy is vulnerable to a 51% attack.

Quote from: Meni Rosenfeld on July 13, 2011, 08:58:51 AM

In a nutshell, if an SMPPS pool with no fees runs long enough, with probability 1 it will eventually reach a point of such unluckiness that its payouts will be miniscule. Miners will leave and the pool will never recover. At that payment miners with pending payments will never receive them.

I don't understand why you say this. With SMPPS, every submitted share has precisely the same expected payout regardless of the past performance of the pool.

Meni Rosenfeld

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Activity: 2058

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Quote from: iopq on July 13, 2011, 08:07:36 AM

Quote from: Meni Rosenfeld on July 13, 2011, 07:20:17 AM

IMO SMPPS is a bad method.

why is that? the only problem I see is that an unlucky pool will get a bad reputation for delaying payments for shares a long time

In a nutshell, if an SMPPS pool with no fees runs long enough, with probability 1 it will eventually reach a point of such unluckiness that its payouts will be miniscule. Miners will leave and the pool will never recover. At that point miners with pending payments will never receive them. So, the claim that "you will get your due reward eventually" is refuted based on the pool's inevitable collapse.

Quote from: NickW on July 13, 2011, 08:09:56 AM

Correct me if I'm wrong, but I believe crossing pool boundaries would mean the "window" could be as long as you wanted. Even 24 hours.

First, defining the window in terms of units of time is bad. You need to define it in terms of number of shares.

But yes, I guess in the multiple-payment variant, you could make the window long. But this will also mean you'll have to make sure you're handling difficulty changes properly.

In the single-payment variant, the window must be less than the difficulty by some margin.

JoelKatz

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Democracy is vulnerable to a 51% attack.

Quote from: NickW on July 13, 2011, 08:09:56 AM

Correct me if I'm wrong, but I believe crossing pool boundaries would mean the "window" could be as long as you wanted. Even 24 hours.

I believe that's correct, which is actually pretty nice.

There could still be 'jackpot' rounds if multiple blocks are found within the window. But there is no way to know that a share is more or less likely to be in the jackpot before you work for it, so that provides no incentive to pool hop. Every share submitted has precisely the same chance to be part of the payoff for any number of found blocks.

NickW

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iopq

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Quote from: Meni Rosenfeld on July 13, 2011, 07:20:17 AM

IMO SMPPS is a bad method.

why is that? the only problem I see is that an unlucky pool will get a bad reputation for delaying payments for shares a long time

JoelKatz

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Democracy is vulnerable to a 51% attack.

Quote from: NickW on July 13, 2011, 05:43:19 AM

Quote from: JoelKatz on July 12, 2011, 05:38:14 PM

Maybe I'm missing something, but I don't see why this prevents or even discourages pool hopping. The reason you would want to leave a proportional pool is because once there are a large number of shares trying to earn the current block, each share you add is expected to be worth less. With this scheme, you still have the same incentive to leave a pool if it has gone a long time without finding a block.

There is no incentive to leave after a long time not finding a block. All results prior to the time window are thrown away, and there is no way of telling if your shares will be in the window or not while mining.

There is an incentive to leave after a long time not finding a block. You know that your future shares will payoff at most 50/N. Once the pool finds a block, there's a chance that future blocks will pay off more than that. So the incentive to leave is that you know the payoff for any shares submitted will be below the pool's average payoff.

And there is no penalty. If the pool soon finds a block, all of your existing shares will payoff (or not payoff) just the same if you leave the pool as if you keep mining for it.

Quote from: JoelKatz on July 12, 2011, 05:38:14 PM

First, by leaving, you have no effect on the value of the shares you have already submitted. They'll either be part of the last N shares or they won't. So you'll still get paid the same for the work already done.

And your new shares are still worth less. This will be a block where >N shares will be submitted in total, while in some blocks

I think you’re missing the point that the each share submitted during the window is worth more than the expected value of a single share in a normal proportional system, even if the window is the full length. Each share in the window is worth more than double (essentially triple) the expected value of a single share otherwise.

Right. And all your past shares have the same probability to be in the window or not in the window if you leave the pool or if you stay. So that's not a reason not to pool hop. And your future shares have no higher probability to be in the window just because the pool hasn't found a block. So that's not a reason not to pool hop.

In other words, this scheme provides no reason not to pool hop.

But it does provide a reason to pool hop. A share found soon after the pool finds a block has a chance at being in a 50/[

Quote from: JoelKatz on July 12, 2011, 05:38:14 PM

So this does nothing to discourage pool hopping. With this scheme, it is still to the miner's advantage to leave a proportional pool and submit to a pay-per-share pool if the proportional pool has gone a long time without solving a block.

No it’s not. The risk you are taking by continuing to submit to the "windowed" pool is that the shares you are submitting are worth much more than shares at a normal proportional or PPS pool, provided that they are inside the window.

But those shares have the same chance to be in the window as always. And they have no chance to be in a 50/[

Quote from: JoelKatz on July 12, 2011, 05:38:14 PM

Worse, if N is large, it actually encourages pool hopping because there's a good chance that joining the pool right after it finds a block will bring a 'jackput' 50/[

This still needs some proper mathematical calculations, but I’m pretty sure the "jackpot" payout for very short rounds is cancelled out by the fact that any hopper trying to do this will then have all of their shares from the start of the round dropped as soon as a particular round is longer than the window.

No, not at all. The jackpot rounds are pure win for people who submit shares during them. Pool hoppers will only want to participate when there's a chance for a jackpot since those rounds will pay above average. As soon as there is no chance for a jackpot, there's an incentive to pool hop, since those shares have no chance at being in a jackpot round and will have an expected payout below average.

As has been said, the N shares must cross a round boundary. There must be no jackpots.

Topic: Pool Hopping: The SIMPLE Solution! - page 2. (Read 7909 times)