Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: Infra-Bayesian haggling, published by hannagabor on May 20, 2024 on The AI Alignment Forum.PrefaceI wrote this post during my scholarship at MATS. My goal is to describe a research direction of the learning theoretic agenda (LTA). Namely, a natural infra-Bayesian learning algorithm proposal that arguably leads to Pareto-optimal solutions in repeated games. The idea originates from Vanessa, I'm expanding a draft of her into a more accessible description.The expected audience are people who are interested in ongoing work on LTA. It is especially suitable for people who are looking for a research direction to pursue in this area.IntroductionThere has been much work on the theory of agents who cooperate in the Prisoner's dilemma and other situations. Some call this behaviorsuperrationality. For example, functional decision theory (FDT) is a decision theory that prescribes such behavior. The strongest results so far are those coming from "modal combat", e.g. Critch. However, these results are of very limited scope: among other issues, they describe agents crafted for specific games, rather than general reasoners that produce superrational behavior in a "naturalized" manner (i.e. as a special case of the general rules of reasoning.)At the same time, understanding multi-agent learning theory is another major open problem. Attempts to prove convergence to game-theoretic solution concepts (a much weaker goal than superrationality) in a learning-theoretic setting are impeded by the so-called grain-of-truth problem (originally observed by Kalai and Lehrer, its importance was emphasized by Hutter).An agent can learn to predict the environment via Bayesian learning only if it assigns non-zero prior probability to that environment, i.e. its prior contains a grain of truth. What's the grain-of-truth problem? Suppose Alice's environment contains another agent, Bob. If Alice is a Bayesian agent, she can learn to predict Bob's behavior only if her prior assigns a positive probability to Bob's behavior.(That is, Alice's prior contains a grain of truth.) If Bob has the same complexity level as Alice, then Alice is not able to represent all possible environments. Thus, in general, Alice's prior doesn't contain a grain of truth. A potential solution based on "reflective oracles" was proposed by Leike, Taylor and Fallenstein. However it involves arbitrarily choosing a fixed point out of an enormous space of possibilities, and requires that all agents involved choose the same fixed point.Approaches to multi-agent learning in the mainstream literature (see e.g. Cesa-Bianchi and Lugosi) also suffer from restrictive assumptions and are not naturalized.Infra-Bayesianism (IB) was originally motivated by the problem of non-realizability, of which the multi-agent grain-of-truth problem is a special case. Moreover, it converges to FDT-optimal behavior in most Newcombian problems. Therefore, it seems natural to expect IB agents to have strong multi-agent guarantees as well, hopefully even superrationality.In this article, we will argue that an infra-Bayesian agent playing a repeated game displays a behavior dubbed "infra-Bayesian haggling". For two-player games, this typically (but, strictly speaking, not always) leads to Pareto-efficient outcome. The latter can be a viewed as a form of superrationality. Currently, we only have an informal sketch, and even that in a toy model with no stochastic hypotheses. However, it seems plausible that it can be extended to a fairly general setting.Certainly it allows for asymmetric agents with different priors and doesn't have any strong mutual compatibility condition. The biggest impediment to naturality is the requirement that the learning algorithm is of a particular type (namely, Upper Confidence Bound). However, we believe that it should be po...