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Formalization of Feedback-Efficient Intelligence

This is my first attempt to formalize the ideas in my blog plost on April 21, 2025. I'm not super mathy, but this is the gist of it.

1. Definitions

  • \( E \): the environment (a partially observable stochastic dynamical system)
  • \( \pi \): the agent’s policy mapping histories to actions, or put more simply, the agent
  • \( \hat{M}_t \): the agent’s learned internal latent model of \( E \) at time \( t \)
  • \( \delta_t \): drift error of \( \hat{M}_t \), i.e., true and internal prediction distributions
  • \( F_t \): feedback from the environment at time \( t \)
  • \( U_t \): utility or task performance at time \( t \)
  • \( I_t = I(F_t ; \Delta \hat{M}_t) \): mutual information between feedback and model update
  • \( \eta_{t} = \frac{I_t}{\Delta U_t} \): feedback efficiency—feedback per unit performance gain at time \( t \)

2. Axiom: Drift in Internal Representations

Unbounded Drift Axiom:

If an internal model is not continually recalibrated with external feedback, then:

\[ \lim_{t \to \infty} \delta_t = \infty \]

(under finite precision and chaotic/stochastic environments)

3. Theorem: No Self-Sufficient Intelligence

Nonzero Feedback Theorem:

No intelligent system can maintain bounded error \( \delta_t < \varepsilon \) without cumulative feedback:

\[ \int_0^\infty \|F_t\| \, dt > 0 \quad \forall \varepsilon > 0 \]

4. Intelligence as Feedback Efficiency

Define feedback needed per unit of utility improvement:

\[ \eta_{t}(\pi) = \limsup_{t \to \infty} \frac{I(F_t ; \Delta \hat{M}_t)}{\Delta U_t} \]

Then agent \( \pi \) is more intelligent than agent \( \pi' \) over task class \( T \) at time \( t \) if:

\[ \eta_{t}^{T}(\pi) < \eta_{t}^{T}(\pi') \]

5. Corollary: The Singularity is Asymptotic

Even self-improving superintelligences cannot reach perfect intelligence (i.e., \( \eta = 0 \)) due to irreducible environmental entropy:

\[ \forall \pi \in \mathcal{A}_{\text{phys}}, \quad \forall t, \quad \eta_{t}(\pi) > 0 \]

Here, \( \mathcal{A}_{\text{phys}} \) denotes the set of all physically realizable agents, that is, agents embedded in environments with bounded memory, finite energy, and nonzero entropy.

6. Model Compression View

  • \( D_{\mathrm{KL}}(P_{E_{t}} \| \hat{P_{t}}) \): divergence between true and internal prediction distributions at time \( t \), where \( \hat{P_{t}} \) is the internal model at time \( t \) and \( P_{E_{t}} \) is the true probability distribution at time \( t \)

Define a new quantity \( \xi_{t} \), which captures the agent’s compression inefficiency. That is, how much model error remains per bit of feedback about the model at time \( t \):

\[ \xi_{t} = \frac{D_{\mathrm{KL}}(P_{E_{t}} \| \hat{P_{t}})}{I(F_t ; \hat{M_{t}})} \]

In contrast to \( \eta_{t} \), which quantifies feedback cost per performance gain, \( \xi_{t} \) quantifies model accuracy per bit of feedback. Both reflect intelligence in different regimes: outer utility vs inner alignment.

Interpretation

This reframes intelligence not as raw computational power or self-sufficiency, but as the ability to compress reality, updating latent models with minimal feedback. The lower the feedback efficiency \( \eta_{t} \), the more intelligent the agent in a task-general sense. The lower the compression inefficiency \( \xi_{t} \), the more precisely it internalizes external structure. In both views, intelligence is fundamentally defined by how efficiently error is reduced per bit of external signal.