The author&#x27;s goal for this design seems to be to increase mining decentralization, but there&#x27;s another big advantage to a blockless graphical ledger over a blockchain. By attaching proof-of-work to each transaction rather than to a block of multiple transactions, a blockless scheme asks miners to answer a simple cost-benefit question: does the payoff to putting the transaction in the ledger (in transaction fees and seignorage) exceed its cost (in hashing resources)?<p>Particularly when seignorage is zero, so that a miner&#x27;s only compensation for providing proof-of-work to a transaction is the fee it offers, this eliminates a free-rider problem created by blocks in a scheme like Bitcoin&#x27;s; as long as you can include as many transactions in a block as you like, the cost of including another one is nil, and so miners have an incentive to include every transaction that pays a non-zero fee, no matter how small [0]. That means the equilibrium price of putting a transaction into Bitcoin&#x27;s blockchain, for example, may never rise much above zero. That&#x27;s a real problem for the long-term security of the Bitcoin blockchain.<p>Per-transaction proof-of-work eliminates that problem by making both the cost and reward of adding a transaction to the ledger a function of the properties of each transaction, rather than of an arbitrary aggregate of transactions.<p>0. This isn&#x27;t true if there is a binding limit on the size of blocks, as there is now in the Bitcoin protocol. But a wholly arbitrary block-size limit is a terrible solution to this problem because it is unresponsive to economic factors. It may be possible that a non-zero equilibrium price of transacting could arise in response to other constraints (like the risk of &quot;orphaning&quot; a large block due to the increased time it takes to propagate around the network), as some people have argued in the course of Bitcoin&#x27;s ongoing block-size war.