## Problem 311 — rank:315

**Title:** Why spliceosomal introns persist

**Added binding assumptions (LaTeX):**

```latex
The marginal occupancy equation is valid for the specified marginal gain/loss intensities; if rates depend on other intron states, these intensities are conditional expectations under the joint process and need not close in $p_j$ alone. Correlated burst statistics require that joint transition law. The constant-rate equilibrium formula is established. Selection, gain supply and loss bias remain confounded without independently constraining their population-genetic mapping.
```

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