Active Inference, The Learn Arc — Part 25: Session §4.3 — Expected Free Energy, Introduced Concretely

Series: The Learn Arc — 50 posts teaching Active Inference through a live BEAM-native workbench. ← Part 24: Session 4.2 . This is Part 25. The session Chapter 4, §3. Session title: EFE intro . Route: /learn/session/4/s3_efe_intro . Chapter 3 gave you G(π) in abstract terms. Session 4.3 shows how the matrices from Sessions 4.1–4.2 — your A, the C you're about to define, and the belief Q(s) you maintain — combine into a number the agent can actually compute. This is the bridge from "the theory pre