[abeppu]

> simply list all structures and pick the structure with the index of the integer

This sounds like to decode a single item you have to do work proportional to the cardinality of the set? Optimal space efficiency comes at a high computational overhead?

[qazxcvbnm]

Yeah, its a theoretical general connection. Once you’ve pinned down the specific structure and know how many structures to skip by virtue of knowing how to count them, it becomes a somewhat practical algorithm.