## Problem 019 — rank:216

**Title:** Establishment of cell polarity

**Added binding assumptions (LaTeX):**

```latex
Use a closed fixed membrane and constant cytosolic volume, or include geometric dilution and area-transport terms. Define sites as connected components of a fixed-resolution superlevel set after a declared persistence filter. To evaluate the probability, supply a random initial condition or a nonexplosive molecule-level law with the same conservation rule; a deterministic PDE without randomness does not define a nontrivial probability.
```

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