Gowers, Green, Manners, and Tao (Annals '25) recently resolved Marton's polynomial Freiman–Ruzsa conjecture. We give an algorithmic counterpart to their result: given uniform sampling and membership-oracle access to a set $A \subseteq \mathbb{F}_2^n$ with doubling constant at most $K$, our algorithm outputs a subspace of size at most $|A|$ whose ... more >>>