  In a Proof-of-Work blockchain such as Bitcoin mining hashrate is increasing
in the block reward. An increase in hashrate reduces network vulnerability to
attack (a reduction in security cost) while increasing carbon emissions and
electricity cost (an increase in externalities cost). This implies a tradeoff
in total cost at different levels of hashrate and the existence of a hashrate
interval where total cost is minimized. Targeted Nakamoto is a Proof-of-Work
protocol augmentation that incentivizes miners to hone in on a target hashrate
interval. When hashrate is above target a ceiling is placed on the block reward
a miner can receive. When hashrate is below target a floor is placed underneath
the miner's block reward. Monetary neutrality is maintained by a proportional
increase in spending potential among addresses holding UTXO's to match a
deduction from total block reward when the ceiling is operative and a
proportional reduction in spending potential among addresses holding UTXO's to
match an increase over the total block reward when the floor is binding.
