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About this paper

Yuansi Chen, Yunbum Kook

The authors analyze Metropolis-corrected Dikin walks using high-probability acceptance control for total-variation mixing and a fourth-order bootstrap for pointwise acceptance and chi-square contraction. For bounded, full-dimensional polytopes with exponential targets, Lee–Sidford, Lewis-weight, and John metrics give a roughly O(d²) iteration bound in total variation. A scaled Lee–Sidford metric gives chi-square mixing in O(d² log²²(em) log((1∨χ²)/ε)), with logarithmic dependence on constraint count.

Key insights

  • It is possible to derive Total-Variation mixing bounds for MCMC algorithms by controlling Metropolis-Hastings acceptance probabilities only within a high-probability region of the state space, relaxing the need for global pointwise control.
  • A novel 'fourth-order bootstrap control' condition allows for self-consistent bounding of higher-order derivative terms of the local metric along proposal paths, which is crucial for establishing robust Average Self-Concordance without dimension-dependent scaling.
  • Combining existing metric regularity conditions with new analytical tools like the high-probability region acceptance and fourth-order bootstrap control enables a deeper and more precise understanding of Dikin walk convergence.

Summary by alphaXiv.

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