## Problem 107 — rank:139

**Title:** Representation drift

**Added binding assumptions (LaTeX):**

```latex
Constrain $B_t$ to predict independently measured behavior with a fixed nonzero performance requirement; otherwise $B_t=0$ for every day gives perfect stability and zero compensation. Fix neuron registration, output scales and the admissible synaptic-change class. Null-space drift and readout adaptation may coexist and may remain observationally equivalent without perturbation.
```

**Direct edits:** 0. **Fresh external checks:** None; supplied sources retained as provenance.