  A growing number of products use layer 2 solutions to expand the capabilities
of primary blockchains like Ethereum, where computation is off-loaded from the
root chain, and the results are published to it in bulk. Those include
optimistic and zero-knowledge rollups, information oracles, and app-specific
chains. This work presents an analysis of layer 2 blockchain strategies
determining the optimal times for publishing transactions on the root chain.
There is a trade-off between waiting for a better layer 1 gas price and the
urgency to finalize layer 2 transactions. We present a model for the problem
that captures this trade-off, generalizing previous works, and we analyze the
properties of optimal publishing strategies. We show that such optimal
strategies hold a computable simple form for a large class of cost functions.
