2025/12/10 by Marumo, Naoki
#65K05 #65K10 #90C26 #90C30 #90C53 #FOS: Mathematics #Optimization and Control (math.OC)
paper · doi:10.48550/arxiv.2512.09439
We propose a quasi-Newton-type method for nonconvex optimization with Lipschitz continuous gradients and Hessians. The algorithm finds an ε-stationary point within O(d1/4 ε-13/8) gradient evaluations, where d is the problem dimension. Although this bound includes an additional logarithmic factor compared with the best known complexity, our method is parameter-free in the sense that it requires no prior knowledge of problem-dependent parameters such as Lipschitz constants or the optimal value. Moreover, it does not need the target accuracy ε or the total number of iterations to be specified in advance. The result is achieved by combining several key ideas: momentum-based acceleration, quartic regularization for subproblems, and a scaled variant of the Powell-symmetric-Broyden (PSB) update.