  We consider the social welfare that can be facilitated by a constant function
market maker (CFMM). When there is sufficient liquidity available to the CFMM,
it can approximate the optimal social welfare when all users transactions are
executed. When one of the agent has the role of proposing the block, and
blockspace is scarce, they can obtain higher expected utility than otherwise
identical agents. This gives a lower bound on the maximal extractable value
exposed when blockspace is scarce.
