Sebastijan Veselic

Authored papers (1)

• Active inference on discrete state-spaces: a synthesis2020ⓒ 212

  Active inference on discrete state-spaces, formalized as partially observable Markov decision processes (POMDPs) with likelihood matrix A, transition matrix B, and prior D, unifies perception, planning, decision-making, learning, and structure learning under two objective functions: variational free energy (an upper bound on surprise minimized during state estimation) and expected free energy G(π) (minimized during policy selection). The synthesis derives neuronal dynamics from first principles via gradient descent on free energy, showing that state estimation corresponds to a softmax function of accumulated prediction errors—equations interpretable as membrane potentials mapping to firing rates—and that these dynamics coincide exactly with variational message passing, while the Bethe approximation yields belief propagation. Policy selection follows Q(π) = σ(−G(π)), where G decomposes into risk (KL divergence between predicted and preferred states) and ambiguity (expected entropy of outcomes given states), formally subsuming KL control, expected utility theory, and optimal Bayesian design as special cases. Learning of A follows Dirichlet parameter accumulation **a** = a + Σ(oτ ⊗ sτ), which is formally equivalent to Hebbian plasticity, while structure learning proceeds via Bayesian model reduction (BMR) for simplification and Bayesian model expansion for concept acquisition, with the marginal approximation implemented in `spm_MDP_VB_X.m` identified as the most biologically plausible free energy approximation. The paper argues this implies that biological cognition—from saccadic sampling at ~4 Hz to dopaminergic precision encoding γ—is fully accountable as free energy minimization, and that the outstanding challenge is identifying the evidence-maximizing generative model an agent actually employs, which would constitute a complete structure learning roadmap.

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Recent mentions (1)

• papers-typed

  dacosta_2020_active_inference_discrete.md