  We study shared sequencing for different chains from an economic angle. We
introduce a minimal non-trivial model that captures cross-domain arbitrageurs'
behavior and compare the performance of shared sequencing to that of separate
sequencing. While shared sequencing dominates separate sequencing trivially in
the sense that it makes it more likely that cross-chain arbitrage opportunities
are realized, the investment and revenue comparison is more subtle: In the
simple latency competition induced by First Come First Serve ordering, shared
sequencing creates more wasteful latency competition compared to separate
sequencing. For bidding-based sequencing, the most surprising insight is that
the revenue of shared sequencing is not always higher than that of separate
sequencing and depends on the transaction ordering rule applied and the
arbitrage value potentially realized.
