Note that some NP-hard optimization problems can be polynomial-time approximated up to some constant approximation ratio (in particular, those in APX) or even up to any approximation ratio (those in PTAS or FPTAS).
Unele probleme de optimizare NP-hard pot fi aproximate⁠(d) în timp polinomial până la un factor de aproximare constant (în special, cele din APX⁠(d)) sau chiar până la orice raport de aproximare (cele din PTAS⁠(d) sau FPTAS⁠(d)).