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They are not mining on the wrong head. They are mining on the current head. If they find a block it will be accepted as the new head and the withheld block will

They are not mining on the wrong head. They are mining on the current head. If they find a block it will be accepted as the new head and the withheld block will be rejected, so it's not wasted mining time at all.

palata 9mo ago
Not an expert, but I have two thoughts: 1. They don't have to wait until another miner finds a block, they can just wait "for some time" and then release their block. All that time gives them the edge for the next block. 2. My understanding is that if two different blocks are found concurrently for the same head, then the network waits for the next block to select which "new head" is accepted. I.e. when there are competing chains, the longer chain wins. So I could imagine that a strategy could be to wait until some other miner announces their block and release yours precisely at that time, hence creating two competing chains. But you presumably have an edge because you have already been mining for a while on top of your block.
- copirate 9mo ago
  There's no edge. Having spent time mining in the past doesn't increase your odds of finding a block in the future.
  - adwn 9mo ago
    The idea is that you can start with the next head earlier than all the others, giving you an edge in being the first to find the next block.
    - copirate 9mo ago
      But what do they gain by doing that? What's the edge? Starting earlier doesn't give you any advantage.
      - palata 9mo ago
        > Starting earlier doesn't give you any advantage It's a race. Starting earlier obviously gives an advantage?!
        copirate 9mo ago
        No it's not a race, it's a lottery. It would be like saying you've an edge if you start earlier at the roulette.
        palata 9mo ago
        I think you're confused. In a lottery, the more tickets you buy, the higher your chances to have the winning number. If we played with a roulette and said "the goal is to be the first to have a winning number at the roulette" and I could try 50 times before you started, obviously I would be more likely to win our game, wouldn't I?
        copirate 9mo ago
        > In a lottery, the more tickets you buy, the higher your chances to have the winning number. Yes, and it's exactly the same in bitcoin with the hashing power. Each hash is a ticket. > If we played with a roulette and said "the goal is to be the first to have a winning number at the roulette" and I can try 50 times before you start, obviously I am more likely to win our game, am I not? In bitcoin the goal is not to be the first. The goal is to find a winning hash that's on a chain that will not be abandoned. As soon as a new block is propagated you start mining on the new head. It doesn't change anything that you previously worked on another chain. The time spent on the previous chain is not wasted, unless finding a block wouldn't have got you the reward. There is a kind of a race if 2 blocks are found simultaneously. But that's not really what this discussion is about, and in this case the outcome depends mostly on network connectivity.
        palata 9mo ago
        It is precisely what this discussion is about. From the article: > The key idea behind this strategy, called Selfish Mining, is for a pool to keep its discovered blocks private, thereby intentionally forking the chain. The honest nodes continue to mine on the public chain, while the pool mines on its own private branch. If the pool discovers more blocks, it develops a longer lead on the public chain, and continues to keep these new blocks private. When the public branch approaches the pool's private branch in length, the selfish miners reveal blocks from their private chain to the public. > In bitcoin the goal is not to be the first. The goal is to find a winning hash that's on a chain that will not be abandoned. The goal is to be the first (or very close to the first), because it makes it much more likely that your chain will not be abandoned. If you wait 2 days before you reveal your block, obviously it will be abandoned...
svara 9mo ago
You can determine statistically whether you have found a block relatively early, and conversely whether other miners are unlikely to find one soon. So you can get a head start on the next block from the likely new head block you've found. It only works on average of course, you might be the one wasting resources if someone else published a block while you're withholding yours, but the trick is for you to gain an edge on average. Now what happens if everyone is doing that calculation? That's where you need to do the game theory analysis (which I haven't and don't claim to understand).
- copirate 9mo ago
  > You can determine statistically whether you have found a block relatively early, and conversely whether other miners are unlikely to find one soon. Finding a block relatively early doesn't affect the odds of others finding a block soon. The odds are always the same, each hash is an independent event. I don't see why withholding would get you an edge on average. If the others find a block while you're withholding, you lose your reward. If you find another block before them, you get the rewards of 2 blocks, exactly like if the same happened but you didn't withhold. The only way for you to have an advantage is if you find a 2nd block at the same time as another one finds one on the other chain. You can then publish a height of 2 vs a height of 1, so you win. But to do that you have to first put your first block reward at high risk by withholding it. I don't think the odds are in your favor here.
  - svara 9mo ago
    Yeah, I was thinking about this wrong. I don't think it works. Edit: I think the strategy does work, but a little differently: if you withhold a block and someone else finds one while you do so, you can still publish yours and win a race with a certain probability, i.e. the expected loss is not as high as one might think. Then, if you do that and if you have enough hash power, you can end up mining a private chain ahead of the public one often enough, so that the loss you take is less than the loss others take through the hash power they are wasting because of you doing this.

palata 9mo ago

Not an expert, but I have two thoughts: 1. They don't have to wait until another miner finds a block, they can just wait "for some time" and then release their block. All that time gives them the edge for the next block. 2. My understanding is that if two different blocks are found concurrently for the same head, then the network waits for the next block to select which "new head" is accepted. I.e. when there are competing chains, the longer chain wins. So I could imagine that a strategy could be to wait until some other miner announces their block and release yours precisely at that time, hence creating two competing chains. But you presumably have an edge because you have already been mining for a while on top of your block.

copirate 9mo ago
There's no edge. Having spent time mining in the past doesn't increase your odds of finding a block in the future.
- adwn 9mo ago
  The idea is that you can start with the next head earlier than all the others, giving you an edge in being the first to find the next block.
  - copirate 9mo ago
    But what do they gain by doing that? What's the edge? Starting earlier doesn't give you any advantage.
    - palata 9mo ago
      > Starting earlier doesn't give you any advantage It's a race. Starting earlier obviously gives an advantage?!
      - copirate 9mo ago
        No it's not a race, it's a lottery. It would be like saying you've an edge if you start earlier at the roulette.
        palata 9mo ago
        I think you're confused. In a lottery, the more tickets you buy, the higher your chances to have the winning number. If we played with a roulette and said "the goal is to be the first to have a winning number at the roulette" and I could try 50 times before you started, obviously I would be more likely to win our game, wouldn't I?
        copirate 9mo ago
        > In a lottery, the more tickets you buy, the higher your chances to have the winning number. Yes, and it's exactly the same in bitcoin with the hashing power. Each hash is a ticket. > If we played with a roulette and said "the goal is to be the first to have a winning number at the roulette" and I can try 50 times before you start, obviously I am more likely to win our game, am I not? In bitcoin the goal is not to be the first. The goal is to find a winning hash that's on a chain that will not be abandoned. As soon as a new block is propagated you start mining on the new head. It doesn't change anything that you previously worked on another chain. The time spent on the previous chain is not wasted, unless finding a block wouldn't have got you the reward. There is a kind of a race if 2 blocks are found simultaneously. But that's not really what this discussion is about, and in this case the outcome depends mostly on network connectivity.
        palata 9mo ago
        It is precisely what this discussion is about. From the article: > The key idea behind this strategy, called Selfish Mining, is for a pool to keep its discovered blocks private, thereby intentionally forking the chain. The honest nodes continue to mine on the public chain, while the pool mines on its own private branch. If the pool discovers more blocks, it develops a longer lead on the public chain, and continues to keep these new blocks private. When the public branch approaches the pool's private branch in length, the selfish miners reveal blocks from their private chain to the public. > In bitcoin the goal is not to be the first. The goal is to find a winning hash that's on a chain that will not be abandoned. The goal is to be the first (or very close to the first), because it makes it much more likely that your chain will not be abandoned. If you wait 2 days before you reveal your block, obviously it will be abandoned...

svara 9mo ago

You can determine statistically whether you have found a block relatively early, and conversely whether other miners are unlikely to find one soon. So you can get a head start on the next block from the likely new head block you've found. It only works on average of course, you might be the one wasting resources if someone else published a block while you're withholding yours, but the trick is for you to gain an edge on average. Now what happens if everyone is doing that calculation? That's where you need to do the game theory analysis (which I haven't and don't claim to understand).

copirate 9mo ago
> You can determine statistically whether you have found a block relatively early, and conversely whether other miners are unlikely to find one soon. Finding a block relatively early doesn't affect the odds of others finding a block soon. The odds are always the same, each hash is an independent event. I don't see why withholding would get you an edge on average. If the others find a block while you're withholding, you lose your reward. If you find another block before them, you get the rewards of 2 blocks, exactly like if the same happened but you didn't withhold. The only way for you to have an advantage is if you find a 2nd block at the same time as another one finds one on the other chain. You can then publish a height of 2 vs a height of 1, so you win. But to do that you have to first put your first block reward at high risk by withholding it. I don't think the odds are in your favor here.
- svara 9mo ago
  Yeah, I was thinking about this wrong. I don't think it works. Edit: I think the strategy does work, but a little differently: if you withhold a block and someone else finds one while you do so, you can still publish yours and win a race with a certain probability, i.e. the expected loss is not as high as one might think. Then, if you do that and if you have enough hash power, you can end up mining a private chain ahead of the public one often enough, so that the loss you take is less than the loss others take through the hash power they are wasting because of you doing this.