Close the logarithmic complexity gap

Determine whether the logarithmic gap between the upper and lower deterministic oracle-complexity bounds for finding an tangent-residual-accurate solution to a composite monotone inclusion problem can be eliminated.

Background

The paper establishes an upper bound of O~(ε−2/(3p−1))\widetilde{O}(\varepsilon^{-2/(3p-1)}) and a matching lower bound of Ω(ε−2/(3p−1))\Omega(\varepsilon^{-2/(3p-1)}) for deterministic ppth-order methods solving composite monotone inclusion problems under the tangent-residual criterion. The remaining discrepancy is logarithmic and arises from the bisection line search used by the Anchored Extra-Proximal Tensor method.

The authors explicitly identify closing this logarithmic discrepancy as an immediate open question, without resolving whether a method can attain the lower bound without the logarithmic overhead.

References

An immediate open question is whether the logarithmic gap between the upper and lower complexity bounds could be closed.

— Anchored Extra-Proximal Methods: Optimal Higher-Order Methods for Monotone Inclusion Problems  (2609.30212 - Jiang et al., 24 Sep 2026) in Conclusion section