Ricci Flow — Surface Geometry Smoothing

Hamilton's ∂g/∂t = −2 Ric(g): curvature-driven metric evolution on 2-manifolds

Surface & Flow

Curvature

Mean K̄
Max |K|
Gauss-Bonnet ∫K dA
∂g_{ij}/∂t = −2 R_{ij}
Normalized: ∂g/∂t = −2(Ric − r̄g)
For 2D: R = scalar curvature
Converges to constant curvature
Proof of Poincaré conjecture (Perelman)