My current best-guess answer for what "HCH + annotated functional programming" and no indirection is:
Instead of initializing the tree with the generic question "what should the agent do next", you initialize the tree with the specific question you want an answer for. In the context of IDA, I think (??) this would be a question sampled from the distribution of questions you want the IDA agent to be able to answer well.
Is it fair to say the HCH + AFP part mainly achieves capability amplification, and the indirection part mainly achieves security amplification?
Edit: apparently I somehow asked the original question under a different account name that I've never used before? In case anyone finds this weird/confusing: both Liam Donovans are the same person, but this is the account I normally use.
I've been trying to understand IDA/Factored Evaluation at a deep level, and I find meta-execution especially confusing. The LW post says that it is "HCH + annotated functional programming + a level of indirection", but I'm not sure what the "level of indirection" is doing. To understand it better, I want to know what HCH + Annotated Functional Programming (without indirection) would look like, and how this differs from meta-execution. Any help is much appreciated!