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arxiv: 2604.04823 · v1 · submitted 2026-04-06 · 🧮 math.PR · math.ST· stat.TH

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Rapid convergence of tempering chains to multimodal Gibbs measures

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Pith reviewed 2026-05-10 19:40 UTC · model grok-4.3

classification 🧮 math.PR math.STstat.TH
keywords spectral gaptempering chainsGibbs measuresmultimodal distributionsMetropolis random walksLyapunov functionsMarkov chain Monte Carloconvergence rates
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The pith

Parallel and simulated tempering chains achieve polynomial lower bounds on spectral gaps for multimodal Gibbs measures.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that tempering chains built from Metropolis random walks at harmonically spaced temperatures have spectral gaps bounded below by polynomials in the inverse of the low target temperature. The bounds are of order 11 for parallel tempering and 12 for simulated tempering. These results hold for a broad class of potentials and do not require any explicit description of the energy landscape or barrier structure. A reader would care because the polynomial scaling guarantees that the chains mix in polynomial time even when the target distribution has many well-separated modes.

Core claim

We study the spectral gaps of parallel and simulated tempering chains targeting multimodal Gibbs measures. In particular, we consider chains constructed from Metropolis random walks that preserve the Gibbs distributions at a sequence of harmonically spaced temperatures. We prove that their spectral gaps admit polynomial lower bounds of order 11 and 12 in terms of the low target temperature. The analysis applies to a broad class of potentials, beyond mixture models, without requiring explicit structural information on the energy landscape. The main idea is to decompose the state space and construct a Lyapunov function based on a suitably perturbed potential, which allows us to establish lower

What carries the argument

State space decomposition combined with a Lyapunov function constructed from a suitably perturbed potential, used to bound the local spectral gaps of the tempering chains.

Load-bearing premise

The state space can be decomposed and a suitably perturbed potential can be constructed to yield lower bounds on the local spectral gaps for the broad class of potentials considered.

What would settle it

A concrete potential in the considered class for which the spectral gap of either tempering chain decays faster than any polynomial in the inverse low temperature would disprove the claimed bounds.

read the original abstract

We study the spectral gaps of parallel and simulated tempering chains targeting multimodal Gibbs measures. In particular, we consider chains constructed from Metropolis random walks that preserve the Gibbs distributions at a sequence of harmonically spaced temperatures. We prove that their spectral gaps admit polynomial lower bounds of order $11$ and $12$ in terms of the low target temperature. The analysis applies to a broad class of potentials, beyond mixture models, without requiring explicit structural information on the energy landscape. The main idea is to decompose the state space and construct a Lyapunov function based on a suitably perturbed potential, which allows us to establish lower bounds on the local spectral gaps.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

0 major / 1 minor

Summary. The manuscript proves that the spectral gaps of parallel and simulated tempering chains, built from Metropolis random walks targeting multimodal Gibbs measures at harmonically spaced temperatures, admit polynomial lower bounds of orders 11 and 12 in the low target temperature. The result is claimed to hold for a broad class of potentials without requiring explicit structural information on the energy landscape. The central technique is a state-space decomposition combined with a Lyapunov function constructed from a suitably perturbed potential, which yields lower bounds on the local spectral gaps.

Significance. If the central claims hold, the work supplies rigorous polynomial-in-temperature mixing guarantees for tempering algorithms on multimodal targets. Such bounds are valuable because they are independent of barrier heights and apply beyond the mixture-model setting that dominates much of the existing literature. The use of standard Markov-chain tools (drift conditions via Lyapunov functions) is a methodological strength, and the generality of the potential class strengthens the result's applicability to statistical physics and Bayesian sampling.

minor comments (1)
  1. [Abstract / Introduction] The abstract states that the bounds are of order 11 and 12 but does not immediately indicate which chain (parallel vs. simulated tempering) receives which exponent; a single clarifying sentence in the introduction would improve readability.

Simulated Author's Rebuttal

0 responses · 0 unresolved

We thank the referee for their positive assessment of the manuscript and for recommending acceptance. We are pleased that the referee highlights the value of polynomial spectral gap bounds that hold without explicit energy landscape structure.

Circularity Check

0 steps flagged

No significant circularity

full rationale

The paper establishes polynomial lower bounds on spectral gaps via an analytic proof that decomposes the state space and constructs a Lyapunov function from a perturbed potential. This relies on standard Markov chain drift conditions and does not reduce to fitted parameters, self-referential definitions, or load-bearing self-citations. The derivation is self-contained against external mathematical benchmarks and does not invoke any of the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

The result rests on standard Markov chain spectral theory plus a domain-specific construction of a state-space decomposition and perturbed potential; no free parameters or new entities are introduced.

axioms (2)
  • standard math Standard spectral gap theory for reversible Markov chains
    Used to relate spectral gap to convergence rate.
  • domain assumption Existence of a suitable state-space decomposition and perturbed potential yielding local gap bounds
    Central technical step stated in the abstract.

pith-pipeline@v0.9.0 · 5392 in / 1186 out tokens · 41668 ms · 2026-05-10T19:40:46.104985+00:00 · methodology

discussion (0)

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Reference graph

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