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I've been trying to understand why PoS is an improvement over PoW. To me PoS seems like a weaker requirement on network control than PoW. Since PoW requires pos

I've been trying to understand why PoS is an improvement over PoW. To me PoS seems like a weaker requirement on network control than PoW. Since PoW requires possession of actual physical hardware and electricity it should be more difficult to obtain than a virtual currency. To me moving from PoW to PoS is analogous to moving off of the gold standard and placing trust in the value of the currency with whomever possesses it.

pwaai 9y ago
As I understand it, it's designed to create price inflation that benefits those holding large amounts of Ether. Please feel free to correct me in case I'm wrong.
- acoye 9y ago
  Yeah, why would smaller holders of ether would be excluded from PoS? Security probably. But it sucks that the small holders cant profit from their property. Maybe there is a need to create a "cooperative" of sorts hodling the eth of many users and running PoS thus rewarding the owners. (like a pool but safety would be way more of an issue compared to PoW)
  - atentaten 9y ago
    There will be validator pools available for those with small amounts of ETH
    - acoye 9y ago
      It feels a bit more risky than mining in a pool don't you think? If a validator pool is hacked you loose your stake. The equivalent in PoW world would be someone breaking in and leaving with all the GPUs of all the users of a pool, what I would consider not dooable for a large enough pool.
      - tuxxy 9y ago
        That's not how it works. When you stake your Ethereum, it gets locked up and can't be withdrawn. When your staking time is up, then you can withdraw it. Smart contracts could be used so that multisignature wallets could be used which would prevent a hacker from taking funds provided to the mining pool. I think a few friends and I are going to start a validator pool when time comes to switch over.
        m-i-l 9y ago
        The validator pool sounds very interesting. Any experience of validator nodes for existing live PoS systems, in particular the costs of running (bandwidth costs, likely datacentre hosting costs, etc) vs rewards?
        acoye 9y ago
        I would like to know too. I know some PoS coins are there but I do not know of existing validator pools.
        m-i-l 9y ago
        The only PoS system in live and large scale active use from I have read so far (still got a lot of reading to do though so could be missing lots) is NEO, and from what I can gather the validator nodes need a stake of 1000 GAS which is currently a little over USD30K, so there isn't such a compelling case for a validator pool compared with the proposed 1500ETH with current market value of over USD1M for the Ethereum proposal.
        PeterisP 9y ago
        A malicious (or pwned) pool operator could do false validation, which would sacrifice all the coins that other people have staked.
      - m-i-l 9y ago
        With a mining pool people could lose their coins which were mined but not transferred to their own wallets.
Agebor 9y ago
This is a good source about it: https://medium.com/@jonchoi/ethereum-casper-101-7a851a4f1eb0 https://medium.com/@jonchoi/ethereum-casper-101-7a851a4f1eb0 Main reasons are deducing centralization and more control for protocol designers to fine-tune incentives and punishments, to increase security.
- ibgib 9y ago
  > protocol designers to fine-tune incentives and punishments This is an interesting phrasing of one of the questions I have about the "decentralized" aspect of cryptocurrencies. I get that the context of the term is that it attempts to bypass the centralization of a fiat currency. But isn't it still centralized to those who develop the protocol itself? Or is the agreement of the community a requirement of the protocol? My heuristic seems to be that the precise protocol implementation decisions are analogous to the precise laws enacted by the centralized governments who provide the value behind mainstream fiat currencies.
  - int_19h 9y ago
    > Or is the agreement of the community a requirement of the protocol? It is, obviously, because if there's no agreement, then nobody (or not enough people to matter) adopt said protocol.
    - ibgib 9y ago
      Yes, I instinctively agree with you. But what about sink investments? Also, what about borderline protocol implementation improvements? Death of a thousand papercuts...that kind of thing? Does keeping the algorithm source in the open, which allows for forks when opportunity presents itself...is that pretty much the optimal strategy against any transaction protocol being abused?
  - Agebor 9y ago
    - is the agreement of the community a requirement of the protocol? Yes. Always with a choice of creating your own rules and convincing other to switch to them. Decentralization in this context would mean different rules for every participant, which is not something that we want - an extreme example of individualism where everyone has different beliefs, so a group cannot accomplish anything.
techman9 9y ago
PoW comes with huge energy and computation requirements that can make scaling infeasibly difficult. It's possible, but challenging, to design a PoS system that is secure and does not consolidate power in the hands of those that own the most currency. This document[0] has a good description of the arguments for PoS and an overview of the theory behind it. [0] https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ
- jacobush 9y ago
  I was with you up until "possible, but challenging". How...
  - techman9 9y ago
    How is it possible or how is it challenging? The FAQ document describes both. It relies on a principle called "Weak Subjectivity" that Vitalik describes in detail here: https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity/ https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov... I'll admit, that I don't have a complete understanding of the theory behind PoS systems, and there are certainly tradeoffs between PoW and PoS, but Vitalik makes the arguments that the benefits of lower energy consumption and quicker transaction fees outweigh the weakened guarantees. Whether you agree with him depends on your values with respect to Cryptocurrency.
- runeks 9y ago
  > PoW comes with huge energy and computation requirements that can make scaling infeasibly difficult. In what way does the energy requirements of PoW have an effect on scaling?
sillysaurus3 9y ago
It is a much weaker requirement than PoW. Part of the reason PoS (a fitting acronym) is successful is because people are hysterical about Bitcoin's energy usage over time. Rightly so. Bitcoin uses a lot of energy, and it's fair to worry. But throughout history, people have always capitalized on fears to get something. Careful that you read these proposals with a skeptical eye. There was an excellent comment on HN that unfortunately I can't dig up anymore, but it went into detail about why PoS has all kinds of subtle issues. Basic issues, like who gets what, can end up with weak guarantees. It's important to remember that Bitcoin, for all its flaws, is almost unkillable. The sole way a government can kill it -- any government -- is to invest >$2B into getting >51% hash power, then launching coordinated malicious doublespends for the purpose of shattering faith in bitcoin. That's it. There's no other way. PoS weakens those guarantees, and before this gets pushed through, it's good to understand in detail what the tradeoffs are, and game out whether that could give centralization any advantages. (And if they say there are no tradeoffs and PoS confers no advantage to centralization compared to PoW, maybe research it and decide for yourself.) This whole auto-drop-my-comments-to-the-bottom censorship is really tiring and just a way to discourage certain people from contributing to HN. I've been a member here since day 2 of the launch of Startup News, and this feels quite unfair. My pleas for reversing this decision have gone unanswered, so I have no idea what to do about it other than rant periodically until I get banned. Nothing good will come of that, but it's just a completely bogus situation. (Yeah, moderation is hard, and I respect that, but jeez. My comments all start out at the bottom and stay there.) </rant>
- RoboTeddy 9y ago
  Weird, this seems like a valuable comment. I wonder what's going on. I hope you keep commenting. Government regulation could drive Bitcoin underground inside a given country. Wouldn't be hard to imagine globalized regulation, a la the US treasury sanctions list. It'd be tough to enforce a ban on cryptocurrency, but doesn't strike me as impossible. It's not hard to take out exchanges like Coinbase. Then could do sting operations to try to catch people willing to transact with Bitcoin in person, etc. One exception: it might be very difficult to enforce a ban on using cryptocurrency to purchase services that are purely digital and don't require identity. No way to run a sting.
konschubert 9y ago
One important point is tat Proof-Of-Work is based on destroying value (electricity) in order to prevent centralization of control. If (!) Proof-Of-Stake is able to achieve the same thing without the costs associated with PoW, then it is simply more efficient. This means that the same value (secured cryptocurrenty) can be obtained at a much lower cost. From a macroeconomic perspective, it is clear that equal results at lower cost must benefit the participants of the economy.
- magnetic 9y ago
  > From a macroeconomic perspective, it is clear that equal results at lower cost must benefit the participants of the economy. Maybe not if that costs is directly related to the security of the network. It takes a certain amount of money $X to control 51% of a POW network. If X is large, it's very hard for any one entity to perform a 51% attack. If X is small, the security bar is low as it becomes more accessible for entities to attack the network. It seemed to me that the high cost of securing the network was the main security feature.
  - konschubert 9y ago
    No, the cost is NOT a necessary requirement for creating a secure network. Capital/stake is. What you say is true for Proof-of-work: The more capital-intensive mining is, the harder the network is to attack. One can say that PoW currencies are secured by a display of capital investment into mining. The stake is the electricity and hardware deprecation that goes into mining a block. Cost is used as a proxy for capital. Proof-of-work takes the middle men out of this: You proof your capital investment (your stake) directly within the protocol.
    - magnetic 9y ago
      > What you say is true for Proof-of-work: The more capital-intensive mining is, the harder the network is to attack. Well I did say "It takes a certain amount of money $X to control 51% of a POW network." Not sure why there is an argument around PoS. Did you mean PoS in your last sentence? It isn't clear to me that PoS is much different, in the sense that you can imagine attacking the network by gaining a larger stake, enough to be "calling the shots on the truth" (ie silencing other stakeholders). There are other comments along these lines so I won't repeat the arguments here.
PretzelPirate 9y ago
It isn't a core tenant of PoW that the resources needed to participate are hard to get, it just so happens that if it is profitable to 'mine', the hardware needed will become scarce. That actually creates a problem, much like in the Bitcoin PoW algorithm, that its easy for the hardware production and ownership to become centralized. PoW also requires large energy consumption as participants will inevitably enter a race to compute the fastest. PoS has the benefit that you still lock away capital, much like in PoW, but rather than backing that capital by money put into hardware and electricity, you cut out the middle man and base the capital off of the value of the network token. Pos also has added security benefits. Vitalik Buterin explains this very well: If someone attacks a PoW blockchain by getting 51+% of the hashing power, the network's only response to recover from the attack is to change the hashing algorithm. This will likely force the network to abandon ASICs since hardware wouldn't exist, and move (at least temporarily) to general-purpose CPUs/GPUs. As soon as the hashing can be done with general purpose computers, the game is over, and the attacker can attack forever without any extra loss of capital, other than electricity. PoS has the benefit that the network can simply cause the attacker to lose their funds and no longer have a stake. If the attacker wants to continue the attack, they have to buy more of the network token to be equal to 51% of the staked value. This will cause a price increase. Each time the attacker attacks, the network will force them to lose their stake, and their money. The attacker won't be able to keep this going forever.
- castratikron 9y ago
  Couldn't another response to someone attacking with 51% mining be to physically destroy their hardware? The Kuwait oil fires were a result of someone wanting to limit control of wealth production.
  - Mtinie 9y ago
    > Couldn't another response to someone attacking with 51% mining be to physically destroy their hardware? Sure, if you can identify the location of the hardware and you happen to be a sovereign nation that can field the matériel required, who also doesn't have a problem instigating an international incident. Now, if you're a single entity or a cartel of entities with the financial and technical resources to launch a majority of hash rate attack, you'll have considered what vectors a counter-attacker would attempt to come at you with. For example, I expect the (simplistic) response to the hypothetical risk vector of "a physical assault on our mining hardware" to be migrated by distributing hardware across a number of data centers and pooling mining computations. Solved blocks are then propagated to the network through a single, obfuscated network node.
AlexCoventry 9y ago
It does mitigate the risk of geographic centralization. It's not good for BTC security that a majority of the mining power is under the jurisdiction of a single nation state.
- konschubert 9y ago
  In the end, it will end up wherever electricity and hardware is cheap...
EGreg 9y ago
PoS doesn't require the network to use more electricity than 3/4 of all the world's countries on something useless and stupid.
companyhen 9y ago
The issue with PoS is that it just makes the rich richer, the more coin you already have, the more reward you'll get. That's why I like NEM's PoI (proof of importance) and Nebulas PoD (proof of devotion) algorithms as a more fair staking method
- api 9y ago
  PoW does that too since mining hardware costs money and is a constant arms race.
- mbrock 9y ago
  In a capitalist system, wealthy nodes will always use their wealth to earn interest.
- GordonS 9y ago
  I've never heard of those algorithms you mention, are you able to give a brief description of them and how they are superior to PoS?
  - companyhen 9y ago
    PoI - https://themerkle.com/what-is-proof-of-importance/ https://themerkle.com/what-is-proof-of-importance/ PoD - https://medium.com/research-center/nebulas-nas-ico-analysis-a-decentralized-search-engine-for-the-blockchain-441dc027a7c5 https://medium.com/research-center/nebulas-nas-ico-analysis-... I'm not too familiar yet as I just started reading about it recently, but these two links should help you understand. They're short reads.
    - GordonS 9y ago
      Hmm, PoI seems almost identical to PoS, but with a 'weighting' calculation to determine 'importance' instead of using the raw value. PoD also seems also identical to PoS, but with a kind of 'gamification' element, whereby the amount staked can give you extra network privileges. TBH, at least after a quick look, both PoI and PoD seem like they are PoS systems, just with some extra bells and whistles that could be added to any PoS system.

pwaai 9y ago

As I understand it, it's designed to create price inflation that benefits those holding large amounts of Ether. Please feel free to correct me in case I'm wrong.

acoye 9y ago
Yeah, why would smaller holders of ether would be excluded from PoS? Security probably. But it sucks that the small holders cant profit from their property. Maybe there is a need to create a "cooperative" of sorts hodling the eth of many users and running PoS thus rewarding the owners. (like a pool but safety would be way more of an issue compared to PoW)
- atentaten 9y ago
  There will be validator pools available for those with small amounts of ETH
  - acoye 9y ago
    It feels a bit more risky than mining in a pool don't you think? If a validator pool is hacked you loose your stake. The equivalent in PoW world would be someone breaking in and leaving with all the GPUs of all the users of a pool, what I would consider not dooable for a large enough pool.
    - tuxxy 9y ago
      That's not how it works. When you stake your Ethereum, it gets locked up and can't be withdrawn. When your staking time is up, then you can withdraw it. Smart contracts could be used so that multisignature wallets could be used which would prevent a hacker from taking funds provided to the mining pool. I think a few friends and I are going to start a validator pool when time comes to switch over.
      - m-i-l 9y ago
        The validator pool sounds very interesting. Any experience of validator nodes for existing live PoS systems, in particular the costs of running (bandwidth costs, likely datacentre hosting costs, etc) vs rewards?
        acoye 9y ago
        I would like to know too. I know some PoS coins are there but I do not know of existing validator pools.
        m-i-l 9y ago
        The only PoS system in live and large scale active use from I have read so far (still got a lot of reading to do though so could be missing lots) is NEO, and from what I can gather the validator nodes need a stake of 1000 GAS which is currently a little over USD30K, so there isn't such a compelling case for a validator pool compared with the proposed 1500ETH with current market value of over USD1M for the Ethereum proposal.
      - PeterisP 9y ago
        A malicious (or pwned) pool operator could do false validation, which would sacrifice all the coins that other people have staked.
    - m-i-l 9y ago
      With a mining pool people could lose their coins which were mined but not transferred to their own wallets.

Agebor 9y ago

This is a good source about it: https://medium.com/@jonchoi/ethereum-casper-101-7a851a4f1eb0 https://medium.com/@jonchoi/ethereum-casper-101-7a851a4f1eb0 Main reasons are deducing centralization and more control for protocol designers to fine-tune incentives and punishments, to increase security.

ibgib 9y ago
> protocol designers to fine-tune incentives and punishments This is an interesting phrasing of one of the questions I have about the "decentralized" aspect of cryptocurrencies. I get that the context of the term is that it attempts to bypass the centralization of a fiat currency. But isn't it still centralized to those who develop the protocol itself? Or is the agreement of the community a requirement of the protocol? My heuristic seems to be that the precise protocol implementation decisions are analogous to the precise laws enacted by the centralized governments who provide the value behind mainstream fiat currencies.
- int_19h 9y ago
  > Or is the agreement of the community a requirement of the protocol? It is, obviously, because if there's no agreement, then nobody (or not enough people to matter) adopt said protocol.
  - ibgib 9y ago
    Yes, I instinctively agree with you. But what about sink investments? Also, what about borderline protocol implementation improvements? Death of a thousand papercuts...that kind of thing? Does keeping the algorithm source in the open, which allows for forks when opportunity presents itself...is that pretty much the optimal strategy against any transaction protocol being abused?
- Agebor 9y ago
  - is the agreement of the community a requirement of the protocol? Yes. Always with a choice of creating your own rules and convincing other to switch to them. Decentralization in this context would mean different rules for every participant, which is not something that we want - an extreme example of individualism where everyone has different beliefs, so a group cannot accomplish anything.

techman9 9y ago

PoW comes with huge energy and computation requirements that can make scaling infeasibly difficult. It's possible, but challenging, to design a PoS system that is secure and does not consolidate power in the hands of those that own the most currency. This document[0] has a good description of the arguments for PoS and an overview of the theory behind it. [0] https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ https://github.com/ethereum/wiki/wiki/Proof-of-Stake-FAQ

jacobush 9y ago
I was with you up until "possible, but challenging". How...
- techman9 9y ago
  How is it possible or how is it challenging? The FAQ document describes both. It relies on a principle called "Weak Subjectivity" that Vitalik describes in detail here: https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity/ https://blog.ethereum.org/2014/11/25/proof-stake-learned-lov... I'll admit, that I don't have a complete understanding of the theory behind PoS systems, and there are certainly tradeoffs between PoW and PoS, but Vitalik makes the arguments that the benefits of lower energy consumption and quicker transaction fees outweigh the weakened guarantees. Whether you agree with him depends on your values with respect to Cryptocurrency.
runeks 9y ago
> PoW comes with huge energy and computation requirements that can make scaling infeasibly difficult. In what way does the energy requirements of PoW have an effect on scaling?

sillysaurus3 9y ago

It is a much weaker requirement than PoW. Part of the reason PoS (a fitting acronym) is successful is because people are hysterical about Bitcoin's energy usage over time. Rightly so. Bitcoin uses a lot of energy, and it's fair to worry. But throughout history, people have always capitalized on fears to get something. Careful that you read these proposals with a skeptical eye. There was an excellent comment on HN that unfortunately I can't dig up anymore, but it went into detail about why PoS has all kinds of subtle issues. Basic issues, like who gets what, can end up with weak guarantees. It's important to remember that Bitcoin, for all its flaws, is almost unkillable. The sole way a government can kill it -- any government -- is to invest >$2B into getting >51% hash power, then launching coordinated malicious doublespends for the purpose of shattering faith in bitcoin. That's it. There's no other way. PoS weakens those guarantees, and before this gets pushed through, it's good to understand in detail what the tradeoffs are, and game out whether that could give centralization any advantages. (And if they say there are no tradeoffs and PoS confers no advantage to centralization compared to PoW, maybe research it and decide for yourself.) This whole auto-drop-my-comments-to-the-bottom censorship is really tiring and just a way to discourage certain people from contributing to HN. I've been a member here since day 2 of the launch of Startup News, and this feels quite unfair. My pleas for reversing this decision have gone unanswered, so I have no idea what to do about it other than rant periodically until I get banned. Nothing good will come of that, but it's just a completely bogus situation. (Yeah, moderation is hard, and I respect that, but jeez. My comments all start out at the bottom and stay there.) </rant>

RoboTeddy 9y ago
Weird, this seems like a valuable comment. I wonder what's going on. I hope you keep commenting. Government regulation could drive Bitcoin underground inside a given country. Wouldn't be hard to imagine globalized regulation, a la the US treasury sanctions list. It'd be tough to enforce a ban on cryptocurrency, but doesn't strike me as impossible. It's not hard to take out exchanges like Coinbase. Then could do sting operations to try to catch people willing to transact with Bitcoin in person, etc. One exception: it might be very difficult to enforce a ban on using cryptocurrency to purchase services that are purely digital and don't require identity. No way to run a sting.

konschubert 9y ago

One important point is tat Proof-Of-Work is based on destroying value (electricity) in order to prevent centralization of control. If (!) Proof-Of-Stake is able to achieve the same thing without the costs associated with PoW, then it is simply more efficient. This means that the same value (secured cryptocurrenty) can be obtained at a much lower cost. From a macroeconomic perspective, it is clear that equal results at lower cost must benefit the participants of the economy.

magnetic 9y ago
> From a macroeconomic perspective, it is clear that equal results at lower cost must benefit the participants of the economy. Maybe not if that costs is directly related to the security of the network. It takes a certain amount of money $X to control 51% of a POW network. If X is large, it's very hard for any one entity to perform a 51% attack. If X is small, the security bar is low as it becomes more accessible for entities to attack the network. It seemed to me that the high cost of securing the network was the main security feature.
- konschubert 9y ago
  No, the cost is NOT a necessary requirement for creating a secure network. Capital/stake is. What you say is true for Proof-of-work: The more capital-intensive mining is, the harder the network is to attack. One can say that PoW currencies are secured by a display of capital investment into mining. The stake is the electricity and hardware deprecation that goes into mining a block. Cost is used as a proxy for capital. Proof-of-work takes the middle men out of this: You proof your capital investment (your stake) directly within the protocol.
  - magnetic 9y ago
    > What you say is true for Proof-of-work: The more capital-intensive mining is, the harder the network is to attack. Well I did say "It takes a certain amount of money $X to control 51% of a POW network." Not sure why there is an argument around PoS. Did you mean PoS in your last sentence? It isn't clear to me that PoS is much different, in the sense that you can imagine attacking the network by gaining a larger stake, enough to be "calling the shots on the truth" (ie silencing other stakeholders). There are other comments along these lines so I won't repeat the arguments here.

PretzelPirate 9y ago

It isn't a core tenant of PoW that the resources needed to participate are hard to get, it just so happens that if it is profitable to 'mine', the hardware needed will become scarce. That actually creates a problem, much like in the Bitcoin PoW algorithm, that its easy for the hardware production and ownership to become centralized. PoW also requires large energy consumption as participants will inevitably enter a race to compute the fastest. PoS has the benefit that you still lock away capital, much like in PoW, but rather than backing that capital by money put into hardware and electricity, you cut out the middle man and base the capital off of the value of the network token. Pos also has added security benefits. Vitalik Buterin explains this very well: If someone attacks a PoW blockchain by getting 51+% of the hashing power, the network's only response to recover from the attack is to change the hashing algorithm. This will likely force the network to abandon ASICs since hardware wouldn't exist, and move (at least temporarily) to general-purpose CPUs/GPUs. As soon as the hashing can be done with general purpose computers, the game is over, and the attacker can attack forever without any extra loss of capital, other than electricity. PoS has the benefit that the network can simply cause the attacker to lose their funds and no longer have a stake. If the attacker wants to continue the attack, they have to buy more of the network token to be equal to 51% of the staked value. This will cause a price increase. Each time the attacker attacks, the network will force them to lose their stake, and their money. The attacker won't be able to keep this going forever.

castratikron 9y ago
Couldn't another response to someone attacking with 51% mining be to physically destroy their hardware? The Kuwait oil fires were a result of someone wanting to limit control of wealth production.
- Mtinie 9y ago
  > Couldn't another response to someone attacking with 51% mining be to physically destroy their hardware? Sure, if you can identify the location of the hardware and you happen to be a sovereign nation that can field the matériel required, who also doesn't have a problem instigating an international incident. Now, if you're a single entity or a cartel of entities with the financial and technical resources to launch a majority of hash rate attack, you'll have considered what vectors a counter-attacker would attempt to come at you with. For example, I expect the (simplistic) response to the hypothetical risk vector of "a physical assault on our mining hardware" to be migrated by distributing hardware across a number of data centers and pooling mining computations. Solved blocks are then propagated to the network through a single, obfuscated network node.

AlexCoventry 9y ago

It does mitigate the risk of geographic centralization. It's not good for BTC security that a majority of the mining power is under the jurisdiction of a single nation state.

konschubert 9y ago
In the end, it will end up wherever electricity and hardware is cheap...

EGreg 9y ago

PoS doesn't require the network to use more electricity than 3/4 of all the world's countries on something useless and stupid.

companyhen 9y ago

The issue with PoS is that it just makes the rich richer, the more coin you already have, the more reward you'll get. That's why I like NEM's PoI (proof of importance) and Nebulas PoD (proof of devotion) algorithms as a more fair staking method

api 9y ago
PoW does that too since mining hardware costs money and is a constant arms race.
mbrock 9y ago
In a capitalist system, wealthy nodes will always use their wealth to earn interest.
GordonS 9y ago
I've never heard of those algorithms you mention, are you able to give a brief description of them and how they are superior to PoS?
- companyhen 9y ago
  PoI - https://themerkle.com/what-is-proof-of-importance/ https://themerkle.com/what-is-proof-of-importance/ PoD - https://medium.com/research-center/nebulas-nas-ico-analysis-a-decentralized-search-engine-for-the-blockchain-441dc027a7c5 https://medium.com/research-center/nebulas-nas-ico-analysis-... I'm not too familiar yet as I just started reading about it recently, but these two links should help you understand. They're short reads.
  - GordonS 9y ago
    Hmm, PoI seems almost identical to PoS, but with a 'weighting' calculation to determine 'importance' instead of using the raw value. PoD also seems also identical to PoS, but with a kind of 'gamification' element, whereby the amount staked can give you extra network privileges. TBH, at least after a quick look, both PoI and PoD seem like they are PoS systems, just with some extra bells and whistles that could be added to any PoS system.