Hi shesek,

Minimum fees may not be the right mechanism. However I disagree with the general idea that "if it's optimal for society to do X then they'll do X". There's plenty of examples where people fail to coordinate in the absence of a suitable framework, see the "free rider" problem with public goods or even the simple prisoner's dilemma. 

On Thu, Mar 2, 2023, 1:39 AM Nadav Ivgi <nadav@shesek.info> wrote:
Hi Giuseppe,

One side-effect this has is that until enough fees accumulate in the mempool to satisfy min_fees, the rational behaviour for miners would be to try and fork the chain tip, competing for the fees in the latest block (+whatever got into the mempool in the meanwhile and can fit in). This could lead to increased reorgs/orphan rates and chain instability. It could also lead to miners preferring to set their low_fee to zero, to avoid other miners from forking their blocks off.

I'm also not sure that this would actually change much. If humanity is willing to spend X BTC/day on mining fees, it doesn't really matter if it's spread out through fewer or more blocks.

shesek

On Wed, Mar 1, 2023 at 10:25 PM Giuseppe B via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org> wrote:
Hello everyone,

I'm relatively new here so what I'm proposing could have already been discussed, or may be flawed or inapplicable. I apologize for that.

I was picturing a situation where block rewards are almost zero, and the base layer is mainly used as a settlement layer for relatively few large transactions, since the majority of smaller ones goes through LN.

In such a case it may very well be that even if transaction amounts are very consistent, transaction fees end up being very small since there is enough space for everyone in a block. Users wouldn't mind paying higher fees as they know that that would increase the network security, however nobody wants to be the only one doing that. Miners would of course like being paid more. So everyone involved would prefer higher fees but they just stay low because that's the only rational individual choice.

Therefore I was imagining the introduction of a new protocol rule, min_fees, that would work like this: 
- the miner that gets to mine a block appends a min_fee field to the block, specifying the minimum fees that need to be contained in the following block in order for it to be valid.
- one can also mine an empty block and reset the min_fee, to avoid the chain getting stuck.

min_fees could either represent the total fees of the following block, or the minimal fee for each single transaction, as a percentage of the value transacted. Both seem to have some merits and some potential drawbacks. Of course min_fees=0 would correspond to the current situation.

It looks to me that this could have the potential to bring the equilibrium closer to a socially optimal one (as opposed to individually optimal), and to benefit the network security in the long term. Of course it's just a rough sketch and it would deserve a much deeper analysis. I was just interested in knowing if you think that the principle has some merit or if it's not even worth discussing it for some reason that I'm not considering.

Cheers,

Giuseppe.

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