This post contains some of my current best guesses at aspects of agent type signatures for which I expect there are useful Selection Theorems, as well as properties of selection optima which I expect are key to proving these type signatures.
This post assumes you have read the intro post on the Selection Theorem program. The intended audience is people who might work on the program, so these blurbs are intended to be link-heavy hooks and idea generators rather than self-contained explanations.
Aspects Of Agent Type Signature
These generally reflect my own current high-level thinking (though not all of the ideas are mine). For a different (and excellent, and better-written) take on similar questions from someone else, check out Mark and Evan’s Agents Over Cartesian World Models.
(A -> B) -> A
Scott Garrabrant’s post (A -> B) -> A provides the basic starting point for a Hofstadter-esque agent type signature. Breaking it down:
A represents the agent’s “actions”.
B represents the “outcomes” of those actions.
(A -> B) is the agent’s model of what outcomes result from an action. It’s a function which takes in actions, and spits out outcomes (that’s the arrow notation).
(A -> B) -> A is the full agent: it takes in the model (A -> B), and then outputs action A as a function of the model.
In pure abstract functional terms, the overall type signature is (A -> B) -> A. Lots of other type information is missing from this - there’s nothing about the types of the actions or the outcomes, for instance. But it seems like the right basic setup at a high level.
(A -> B) -> A + Abstraction
Generally speaking, low-level physical reality seems to be made of something like a giant causal network with symmetry. It doesn’t have any built-in “clouds” or “strange loops”. So, how do we get (A -> B) -> A structures in the physical world?
I expect that some chunks of the world naturally abstract into models with an agent-like type signature. In other words, approximately-all of the information about that chunk which propagates “far away” in the low-level causal network of the universe is summarized by a high-level model with an (A -> B) -> A signature.
This is the sort of “embedding” of agents for which I expect to find selection theorems.
World Models and Natural Abstractions
Humans’ world models sure do seem to have things in them - pencils, cars, other humans, etc. So a type signature for human world models (and, I expect, probably world models more generally) should give us some idea of what “things” are and how they correspond to structures in the world.
A different angle: to the extent that we expect to see roughly-Bayesian models (which is itself debatable, but at least better founded than EU maximization), what are the variables in those models, and how do they correspond to structures in the world?
This is another place where I expect the Natural Abstraction Hypothesis is relevant. Eventually, I expect to find selection theorems saying that agents evolve to reason using natural abstractions under a fairly broad range of conditions.
Goal Inputs
I’m surprised by just how much of a blindspot goal-inputs seem to be for today’s economists, AI researchers, etc. The coherence theorems usually cited to justify expected utility maximization models imply a quite narrow range of inputs to those utility functions: utilities are only over the outcomes on which agents can bet. Yet practitioners use utility functions over entire (unobservable) world states, world state trajectories, MDP states, etc, often without any way for the agent to bet on all of the outcomes.
Not that I think this is wrong; the inputs to human values seem to be abstract latent variables in humans’ world models, which are not things for which we can operationalize direct bets even in principle. (Indeed, this is arguably the fundamental barrier to making betting markets really useful.) The goal type signatures implied by the coherence theorems are not a good fit for realistic agenty syst...