## Problem 156 — rank:90

**Title:** Evolution of evolvability

**Added binding assumptions (LaTeX):**

```latex
Define the mutation kernel and its normalization, including which background distribution weights beneficial effects. The relationship between a positive rare-modifier growth exponent and fixation above $1/N$ is model-dependent, especially with linkage or structure. Treat these as separate criteria unless their equivalence is proved under explicit exchangeability and weak-selection assumptions. Evolving mutation supply and direct replication costs enter the same demographic normalization.
```

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