Taxonomy of transaction sequencing mechanisms 2.0

This post presents "Taxonomy 2.0," an overview of sequencing mechanisms and how they affect transaction execution fairness, and it argues that sequencing rules can be applied at different levels of the EVM application stack, each with its own trade-offs and fairness guarantees. It builds on a Flashbots forum taxonomy from Quintus that classifies sequencing rules by runtime complexity. The post lists six ordering mechanisms used by sequencers in practice and notes that verifiable sequencing rules provide provable execution price guarantees, although a Condorcet cycle can arise when transactions contain several swaps. It reports that 18.7% of DEX trades in the first four months of 2024, per Dune data, were placed in multi-swap transactions.