Site percolation on ℤ²:
p_c ≈ 0.5927 (no exact form).

At criticality, the cluster
hull converges to SLE₆
(Smirnov 2001, Fields Medal).

Fractal dim: d_f = 91/48 ≈ 1.896
Hull dim: d_H = 7/4 = 1.75

Critical exponents:
ν = 4/3, β = 5/36, γ = 43/18