## Problem 045 — rank:218

**Title:** Mechanistic model selection

**Added binding assumptions (LaTeX):**

```latex
A positive uniform separation is not implied merely by distinct mechanisms. Nested or intersecting observable-law families make the displayed infimum zero; even disjoint families can have touching closures. Specify margin-separated compact subfamilies for a uniform test, or formulate pointwise discrimination and sample-size-dependent power. Model rejection remains possible when every candidate is misspecified.
```

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