## Problem 289 — rank:191

**Title:** Origin of biological homochirality

**Added binding assumptions (LaTeX):**

```latex
Under exact mirror symmetry of initial and dynamical laws, two opposite prescribed global handedness outcomes have equal probability; when disjoint, either prescribed outcome has probability at most $1/2$. Reliable selection of a fixed sign therefore needs a modeled bias, while reliable emergence of either sign is a different criterion. Specify concentration floors, the sign conventions of every chemical class and joint stereochemical observations through subsequent processing.
```

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