Marginals Before Conditionals
- URL: http://arxiv.org/abs/2603.10074v1
- Date: Tue, 10 Mar 2026 05:51:01 GMT
- Title: Marginals Before Conditionals
- Abstract summary: We construct a minimal task that isolates conditional learning in neural networks.<n>The model learns the marginal P(A | B) first, producing a plateau at exactly log K, before acquiring the full conditional.
- Score: 0.15229257192293197
- License: http://creativecommons.org/licenses/by/4.0/
- Abstract: We construct a minimal task that isolates conditional learning in neural networks: a surjective map with K-fold ambiguity, resolved by a selector token z, so H(A | B) = log K while H(A | B, z) = 0. The model learns the marginal P(A | B) first, producing a plateau at exactly log K, before acquiring the full conditional in a sharp, collective transition. The plateau has a clean decomposition: height = log K (set by ambiguity), duration = f(D) (set by dataset size D, not K). Gradient noise stabilizes the marginal solution: higher learning rates monotonically slow the transition (3.6* across a 7* η range at fixed throughput), and batch-size reduction delays escape, consistent with an entropic force opposing departure from the low-gradient marginal. Internally, a selector-routing head assembles during the plateau, leading the loss transition by ~50% of the waiting time. This is the Type 2 directional asymmetry of Papadopoulos et al. [2024], measured dynamically: we track the excess risk from log K to zero and characterize what stabilizes it, what triggers its collapse, and how long it takes.
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