FitnessSharing

Fitness sharing for the ISC global phase (§A.4). The raw fitness f (the penalized objective, minimized) is discounted by the niche size m so that members in crowded niches become less attractive: f_sh = f / m when f < 0 and f_sh = f · m when f ≥ 0 (both move f toward a worse — larger — value as m grows). The objective-estimate variance is scaled by the same m. Members not assigned to any niche form a single non-niched group whose size plays the role of m (triangular sharing).