computo ergo sum

2026-10-09 · chapter Yang–Mills and the mass gapPart 10 Towards a proof of the mass gap — building the first step of the staircaseProposition 4.5, conditions (H1)–(H4), dependency graph · Kiichi, Shiori and Rin

The whole book Contents and reading orders
  1. Part 0 Entrance — how to read this book
  2. 0-01 How to read this book
  3. 0-02 One picture
  4. 0-03 Reading the problem statement word by word
  5. 0-04 Four dimensions in mathematics and four dimensions in physics
  6. Part 1 Mathematical preparation
  7. 1-01 Vector spaces and linear maps
  8. 1-02 What a group is
  9. 1-03 Lie groups and Lie algebras
  10. 1-04 SU(2) and SU(3)
  11. 1-05 Manifolds and tangent spaces
  12. 1-06 Differential forms and the exterior derivative
  13. 1-07 Vector bundles and connections
  14. 1-08 Probability and measure
  15. 1-09 Probability in infinite dimensions
  16. 1-10 Hilbert spaces and self-adjoint operators
  17. 1-11 Fourier analysis and distributions
  18. 1-12 Detour: what happens only in four dimensions
  19. Part 2 Physical preparation
  20. 2-01 Lagrangians and the action
  21. 2-02 The idea of a field
  22. 2-03 Electromagnetism is a gauge theory
  23. 2-04 Special relativity and spacetime
  24. 2-05 The bones of quantum mechanics
  25. 2-06 The harmonic oscillator and creation and annihilation
  26. 2-07 The idea of the path integral
  27. 2-08 Statistical mechanics and phase transitions
  28. 2-09 Detour: the gap and the correlation length in the Ising model
  29. 2-10 The relaxation time and the dynamical exponent z
  30. Part 3 Yang–Mills theory (classical)
  31. 3-01 The gauge principle
  32. 3-02 Non-abelian gauge fields
  33. 3-03 The action and the equations
  34. 3-04 Gauge theory as geometry
  35. 3-05 Instantons and topology
  36. 3-06 Detour: Donaldson and exotic R⁴
  37. 3-07 Yang–Mills inside the Standard Model
  38. Part 4 Quantisation
  39. 4-01 Canonical quantisation and the Hamiltonian
  40. 4-02 The path integral and Euclideanisation
  41. 4-03 Perturbation theory and Feynman diagrams
  42. 4-04 Divergences and renormalisation
  43. 4-05 The algebra of divergences
  44. 4-06 Asymptotic freedom
  45. 4-07 Dimensional transmutation and Λ
  46. 4-08 Gauge fixing and Faddeev–Popov
  47. 4-09 The axioms of quantum field theory
  48. 4-10 The Osterwalder–Schrader axioms and reconstruction
  49. 4-11 The definition of the mass gap
  50. 4-12 Detour: the perturbation series diverges
  51. Part 5 Lattice gauge theory
  52. 5-01 Wilson's lattice
  53. 5-02 The strong-coupling expansion
  54. 5-03 Reflection positivity and the transfer matrix
  55. 5-04 The infinite-volume limit and the cluster expansion
  56. 5-05 Weak coupling and the continuum limit
  57. 5-06 How U(1) differs from the non-abelian case
  58. 5-07 The Monte Carlo method
  59. 5-08 Measuring glueballs and the string tension
  60. 5-09 What to hold fixed when taking the limit
  61. 5-10 Lattice gauge theory with finite groups
  62. 5-11 Detour: Bakry–Émery and one-link integration
  63. Part 6 Constructive field theory
  64. 6-01 What constructive field theory is
  65. 6-02 Solvability in two dimensions and the Yang–Mills measure
  66. 6-03 Constructing scalar fields
  67. 6-04 The cluster expansion
  68. 6-05 The sequence of renormalisation group steps
  69. 6-06 Ultraviolet stability of three-dimensional Yang–Mills
  70. 6-07 Four dimensions
  71. 6-08 Triviality of φ⁴ in four dimensions
  72. 6-09 Stochastic quantisation and regularity structures
  73. 6-10 Where four dimensions stops
  74. 6-11 Obstacles other than divergence
  75. 6-12 Detour: "if 1/0 is given a symbol"
  76. Part 7 From the side of physics
  77. 7-01 How physics sees it
  78. 7-02 Mechanisms of confinement
  79. 7-03 The string picture
  80. 7-04 Large N
  81. 7-05 String theory and extra dimensions
  82. 7-06 How extra dimensions become invisible
  83. 7-07 Where gauge fields come from
  84. 7-08 Holography
  85. 7-09 The mass gap becomes geometry
  86. 7-10 Back to four dimensions
  87. 7-11 Supersymmetry and Seiberg–Witten
  88. 7-12 The sentence that plays the role of an equivalence principle
  89. 7-13 Where the way physics digs parts from mathematics
  90. Part 8 A dictionary of two languages — the physical and the mathematical view
  91. 8-01 How to read the dictionary
  92. 8-02 Dictionary A
  93. 8-03 Dictionary B
  94. 8-04 Dictionary C
  95. 8-05 The physical counterparts of our assumptions
  96. Part 9 Where things stand, and open tasks
  97. 9-01 How far the world has come
  98. 9-02 Where the two ways of digging part
  99. 9-03 Candidates for new concepts
  100. 9-04 The list of open tasks
  101. 9-05 Common misconceptions
  102. Part 10 Towards a proof of the mass gap — building the first step of the staircase
  103. 10-00 Entrance — the staircase, and the random walk, the ruler and the clock
  104. 10-01 The line of construction and Assumption H
  105. 10-02 Roads tried on the four-dimensional lattice, and walls
  106. 10-03 The four steps of the staircase — why we start from 0+1 dimensions
  107. 10-04 The path measure of the double well, and kinks
  108. 10-05 The statement of the first step — four conditions and Proposition 4.5
  109. 10-06 (H1) Local Poincaré within a phase
  110. 10-07 The map of (H2) — seven routes and the seam of the ring
  111. 10-08 What computer-assisted means — the conditions on the chain inside the window
  112. 10-09 The sector framework and the three strands of route 5
  113. 10-10 The list of detour plans — types of breakage
  114. 10-11 (H3)(H4) and the constant of the core
  115. 10-12 The integrated table and the dependency graph
  116. 10-13 Lean statements and the limits of machine checking
  117. 10-14 Reconciliation — the numbers of the record and the known numbers
  118. 10-15 What remains and its cost — the distance to a theorem
  119. 10-16 What is not claimed
  120. 10-17 Insights and small questions
  121. Part 11 Further considerations — beyond Assumption H, and other views
  122. 11-00 Further considerations — entrance
  123. 11-01 One form that obstructs H — a nearly conserved global quantity
  124. 11-02 Choosing the ruler and the coordinates again — the length at which conservation breaks
  125. 11-03 Two ways to repair H — the sector H and the local H
  126. 11-04 Which H the one-sided bridge needs
  127. 11-05 Making time continuous — the Hamiltonian lattice and the vacuum measure
  128. 11-06 Paying with rarity instead of convexity — renormalisation on groups and log-Sobolev
  129. 11-07 Because it is four dimensions — the dimensionless coupling and topology
  130. 11-08 Questions, and what is not claimed
  131. 11-A1 Table of notation for Part 11
  132. Appendices
  133. A-01 Table of notation
  134. A-02 Glossary
  135. A-03 Guide to the literature
  136. A-04 Lean and machine checking
  137. A-05 How this book was made
  138. A-06 Index of assumptions

The statement of the first step — four conditions and Proposition 4.5

What this chapter shows — We split the upper side CP≤Kξ2S0/ℏC_P\le K\xi^2S_0/\hbar for the path measure of the double well into four conditions (H1)–(H4). Condition (H3) reduces infinitely long paths to boxes of length CξC\xi, condition (H4) controls the gap inside a box, and conditions (H1)(H2) enter (H4) as the fast part inside the box. On top of this we state, as one line of argument, how R=CP/ξ2R=C_P/\xi^2 is squeezed into 1≤R≤K′/ℏ1\le R\le K'/\hbar and the power form of H follows, adding for each step "what it uses and which grade it has". At the end of the chapter the steps of Proposition 4.5 are collected in a table of the five grades and a dependency graph.

Prerequisite chapters — 10-03 §05 (the power form of H and the shape of Proposition 4.5), 10-04 (the path measure, kinks, Proposition L), 1-10 §07–§09 (Poincaré inequalities), 10-00 §01 (the labels of the five grades).

Said first — The level is [Y3]. Proposition 4.5 is algebra on top of four conditions, and every one of the four conditions leaves assumption rows. This chapter does not say that the first step is closed. It names what would have to be shown to close it. This part is a study that chose Assumption H as its foothold, and the split into four conditions is one way of building within it. Other views are treated in Part 11.

The order of this chapter
  1. The splitting of the variance — the algebra of splitting into two valleys, and why that alone is not enough for long paths
  2. The parts shown — the algebra of the splitting, the convex core, the reduced plateau, the diffusion coefficient of kinks
  3. The statements of the four conditions — for which measure, which constant, uniform in what
  4. Proposition 4.5 as one line — reduction to the box → inside the box → CP≤Kξ2S0/ℏC_P\le K\xi^2S_0/\hbar → R≤K′/ℏR\le K'/\hbar → the power form of H
  5. The distance from known theorems — where they reach and where they do not (Table 1)
  6. The table of the five grades — the rows of the steps of Proposition 4.5 (Table 2)
  7. The dependency graph — checking by the numbers that there is no circle
  8. A ℏ\hbar that fits all, and where the four conditions stand — a guide to 10-06–10-12

01

The splitting of the variance — the algebra of splitting into two valleys

The setting is as in 10-04 §01. The lattice is ε=12\varepsilon=\tfrac12, the action SlatS_{\rm lat}, the measure μ∝e−Slat/ℏ\mu\propto e^{-S_{\rm lat}/\hbar}, the Dirichlet form E(f)=(ℏ/ε)∑iE∣∂if∣2\mathcal E(f)=(\hbar/\varepsilon)\sum_i\mathbb E|\partial_if|^2, CP=sup⁡fVar⁡(f)/E(f)C_P=\sup_f\operatorname{Var}(f)/\mathcal E(f), the diffusion coefficient of kinks D=ℏ/S0D=\hbar/S_0, and S0=2/3S_0=2/3. We take T→∞T\to\infty first and then ℏ→0\hbar\to0.

The first tool for building the upper side is the algebra of splitting the measure into two parts. Split the space of configurations in two (for example by the sign of the smoothed value of the path) and write μ=Z+μ++Z−μ−\mu=Z_+\mu_++Z_-\mu_- (Z±≥0Z_\pm\ge0, Z++Z−=1Z_++Z_-=1, and μ±\mu_\pm the measures restricted to each part and normalised). Then for every ff

Var⁡μf=Z+Var⁡μ+f+Z−Var⁡μ−f+Z+Z−(Eμ+f−Eμ−f)2(1)\operatorname{Var}_\mu f=Z_+\operatorname{Var}_{\mu_+}f+Z_-\operatorname{Var}_{\mu_-}f+Z_+Z_-\bigl(\mathbb E_{\mu_+}f-\mathbb E_{\mu_-}f\bigr)^2 \tag{1}

holds Proved here (the identity for the variance of a mixture. Put m±=Eμ±fm_\pm=\mathbb E_{\mu_\pm}f and m=Z+m++Z−m−m=Z_+m_++Z_-m_-, split Eμ(f−m)2\mathbb E_\mu(f-m)^2 on each part into f−m±f-m_\pm and m±−mm_\pm-m, and use Z+(m+−m)2+Z−(m−−m)2=Z+Z−(m+−m−)2Z_+(m_+-m)^2+Z_-(m_--m)^2=Z_+Z_-(m_+-m_-)^2).

Suppose that each of the three terms on the right-hand side has the following inequality.

Var⁡μ±f≤Cloc E±(f),(Eμ+f−Eμ−f)2≤Cmd E(f),Z+E+(f)+Z−E−(f)≤E(f)(2)\operatorname{Var}_{\mu_\pm}f\le C_{\rm loc}\,\mathcal E_\pm(f),\qquad \bigl(\mathbb E_{\mu_+}f-\mathbb E_{\mu_-}f\bigr)^2\le C_{\rm md}\,\mathcal E(f),\qquad Z_+\mathcal E_+(f)+Z_-\mathcal E_-(f)\le\mathcal E(f) \tag{2}

The first is local Poincaré inside a valley, the second is the "transport of the mean difference", which controls the difference of the means of the two valleys by the Dirichlet form, and the third is the additivity of the form. Since Z+Z−≤14Z_+Z_-\le\tfrac14,

CP ≤ Cloc+Cmd4(3)C_P\ \le\ C_{\rm loc}+\frac{C_{\rm md}}{4} \tag{3}

holds Proved here Leansplit_poincare_le (assumptions: Z++Z−=1Z_++Z_-=1, Z±≥0Z_\pm\ge0, the splitting formula (1), the two local Poincaré inequalities, the mean difference, additivity of the form, non-negative constants). The splitting formula (1) has the same form as Lemma 2.4 of Menz–Schlichting Cited (the skeleton of the Poincaré version of finite-dimensional Eyring–Kramers).

Of the two constants in (3), ClocC_{\rm loc} later becomes condition (H1) and CmdC_{\rm md} becomes condition (H2). But (3) cannot be applied to long paths as it stands.

For long paths, one coarse variable is not enough. (1) is a split of the form "take one slow variable (which valley the path is in) and treat the rest as fast". When the path is much longer than the correlation length (T≫ξT\gg\xi), long-wave fluctuations of the density of kinks form a continuous band, and the Poincaré constant of the conditional measure with one valley fixed stays of the same size as ξ2/D\xi^2/D (the Glauber band of 10-04 §05). That is, ClocC_{\rm loc} does not become O(1)O(1). So instead of taking a number of slow variables proportional to the volume, we cut the problem into boxes of length CξC\xi. This is condition (H3) (reduction to the box) and (H4) (the gap inside the box), and (H1)(H2) are used inside the box (§04).

02

The parts shown — the algebra of the splitting, the convex core, the reduced plateau, the diffusion coefficient

First we list the parts of the construction of the upper side that can be said without assumption rows.

(a) The algebra of the splitting. (1)–(3) are as in §01 Proved here.

(b) The convex core. For the measure restricted to the convex region deep in a valley, {xi≥a ∀i}\{x_i\ge a\ \forall i\} (a>1/3a\gt1/\sqrt3), the Hessian of the action is at least εκa\varepsilon\kappa_a (κa=(3a2−1)/2\kappa_a=(3a^2-1)/2), so Bakry–Émery on a convex region gives CP≤2/(3a2−1)C_P\le2/(3a^2-1) uniformly in the length, ℏ\hbar and the boundary Proved here (the lower bound on the curvature) Cited (Bakry–Émery on a convex region, Theorem 1.2 of Kolesnikov–Milman). The proof and the Lean statement are in 10-04 §06. But excursions out of the core have smaller action than a kink, and exponentially many of them fit in an interval of length ξ\xi, so the convex core alone does not give (H1).

(c) The two-state value of the reduced plateau. On a short ring (T≪ξT\ll\xi) the path that moves between valleys is one pair of kinks, and the separation ℓ\ell of the pair becomes the one slow coordinate. In the one-dimensional model that keeps only ℓ\ell (ℓ\ell moves with diffusion coefficient 2D2D, with an atom of a valley at each end and the plateau weight π(ℓ)\pi(\ell) in between), we control the mean difference by the Cauchy–Schwarz inequality, write the difference of the values at the two ends of ℓ\ell as ∫f′(ℓ) dℓ\int f'(\ell)\,d\ell, and

(f(right valley)−f(left valley))2 ≤ ∫dℓπ(ℓ)⋅∫π(ℓ) f′(ℓ)2 dℓ(4)\bigl(f(\text{right valley})-f(\text{left valley})\bigr)^2\ \le\ \int\frac{d\ell}{\pi(\ell)}\cdot\int\pi(\ell)\,f'(\ell)^2\,d\ell \tag{4}

gives a value of the form Cmd/4=J/(4D)C_{\rm md}/4=J/(4D), with equality nearly attained by the sign test function Proved here ((4) is the Cauchy–Schwarz inequality) Leanreduced_two_state_value (assumptions: 0<T0\lt T, 0<D0\lt D, J=4ξ2I/TJ=4\xi^2I/T, with II the integral of the plateau weight). The reduced model itself (that everything other than ℓ\ell may be thrown away) is an assumption of the model, and this value is "a value on the reduced model" Assumption.

(d) The diffusion coefficient of kinks. The position of a single kink moves with diffusion coefficient D=ℏ/S0D=\hbar/S_0. At the level of the process of a single interface, this is a copy of the coefficient of a known theorem Cited ((9) of 10-04 §03). It is not a statement about the gap of the whole path.

These four are all. The remaining parts, namely that local Poincaré inside a valley is uniform in the length and in ℏ\hbar, that transport along the family of flat saddles is uniform in the dimension, the reduction of long paths to boxes, and the gap inside a box, lie outside the assumptions of known theorems (§05). We name them as four conditions.

03

The statements of the four conditions — for which measure, which constant, uniform in what

We write the four conditions making three things explicit: the measure, the constant and the uniformity. All are statements about the 0+1-dimensional double well V=(x2−1)2/8V=(x^2-1)^2/8, the lattice ε=12\varepsilon=\tfrac12 and the Dirichlet form E\mathcal E. "Uniform" means that for some ℏ0>0\hbar_0\gt0 with ℏ∈(0,ℏ0]\hbar\in(0,\hbar_0], the constant does not depend on ℏ\hbar (does not grow as ℏ→0\hbar\to0).

Condition (H1) Local Poincaré within a phase

Measure: the measure of the phase without kinks. The measure μ(+)=μ(⋅∣xi≥0 ∀i)\mu^{(+)}=\mu(\cdot\mid x_i\ge0\ \forall i) restricted to configurations in which the path stays on the side of one valley, for example to configurations with xi≥0x_i\ge0 at every site (reflected at the wall xi=0x_i=0). Constant: the Poincaré constant ClocC_{\rm loc} of μ(+)\mu^{(+)}, that is, Var⁡μ(+)f≤Cloc E(f)\operatorname{Var}_{\mu^{(+)}}f\le C_{\rm loc}\,\mathcal E(f). Uniformity: Cloc=O(1)C_{\rm loc}=O(1) uniformly in ℏ\hbar and in the length of the path. For use inside the box, the version (H1seg) for scraps with end values (length ≤Cξ\le C\xi) is needed, and it must also be uniform in the end values.

Condition (H2) Transport along the family of flat saddles

Measure: the conditional measure of configurations in the tube around the family of kink–antikink pairs (the family of saddles, parametrised by the centre XX and separation ℓ\ell of the pair, along which the action is almost flat). Constant: the constant of transport of the mean difference along that family from valley to valley (of the type of CmdC_{\rm md} in (2)), and the Poincaré constant inside the tube. Uniformity: uniform in the number of sites of the path (the dimension) and in ℏ\hbar. For use inside the box it becomes two rows: Poincaré in the tube uniform in tube length ≤Cξ\le C\xi (H2tube), and Poincaré of the core inside the tube (the interval that stays near the top) uniform in the core length kk (T0′P).

Condition (H3) Reduction to the box dynamics

Measure: the measure μ\mu on the lattice line Z\mathbb Z with T=∞T=\infty, and the conditional measure μBa,b\mu_B^{a,b} with the values (a,b)∈R2(a,b)\in\mathbb R^2 on both neighbours of a box BB of length LL sites (Lε=CξL\varepsilon=C\xi) fixed. Constants: Cbox(L):=sup⁡a,b∈RCP(μBa,b)C_{\rm box}(L):=\sup_{a,b\in\mathbb R}C_P(\mu_B^{a,b}) and the constant cMc_M of mixing between boxes. Statement: CP(μ)≤Cbox(L)/cMC_P(\mu)\le C_{\rm box}(L)/c_M. Uniformity: cMc_M depends only on lengths in units of ξ\xi (CC and the fraction of overlap of the boxes), not on ℏ\hbar or the boundary values.

Condition (H4) The gap inside the box

Measure: the conditional measure μBa,b\mu_B^{a,b} of a box of length CξC\xi. The number of kinks in the box is O(1)O(1) on average (the density of kinks is 1/(2ξ)1/(2\xi), so the expectation is C/2C/2). Constant: the gap 1/CP(μBa,b)1/C_P(\mu_B^{a,b}). Statement: 1/CP(μBa,b)≥c D/(Cξ)21/C_P(\mu_B^{a,b})\ge c\,D/(C\xi)^2, that is, Cbox≤K4(Cξ)2/DC_{\rm box}\le K_4(C\xi)^2/D (K4=1/cK_4=1/c). Uniformity: cc is uniform in ℏ\hbar and in all boundary values (a,b)(a,b) (it may depend on CC).

The four are not conditions of the same weight. (H3) is the step that "moves the problem of long paths to a problem of boxes", (H4) is the step that "splits the inside of a box into slow variables (the arrangement of kinks) and fast variables", and (H1)(H2) are statements on the side of those fast variables. The next section puts into one line the place where (H1)(H2) enter (H4).

To be precise, the conditions named (H1)–(H4) are different from Assumption H (the power statement, 10-01 §05). Assumption H is a statement on the side of the conclusion, and (H1)–(H4) are conditions put in place to derive it in the first step (10-03 §05).

04

Proposition 4.5 as one line

Proposition 4.5 (conditional)

For the path measure of the 0+1-dimensional double well (lattice ε=12\varepsilon=\tfrac12, taking T→∞T\to\infty first), assume conditions (H1)–(H4) and the premise rows of Step 0 below. Then as ℏ→0\hbar\to0

CP ≤ K ξ2 S0ℏ=K ξ2D(K depends only on the constants of the conditions, not on ℏ )(5)C_P\ \le\ K\,\xi^2\,\frac{S_0}{\hbar}=K\,\frac{\xi^2}{D}\qquad(K\ \text{depends only on the constants of the conditions, not on}\ \hbar\ \text{}) \tag{5}

holds, hence 1≤R=CP/ξ2≤KS0/ℏ1\le R=C_P/\xi^2\le KS_0/\hbar, and the power form of H, ln⁡CP/ln⁡ξ→2\ln C_P/\ln\xi\to2, follows.

(5) is the same formula as (15) of 10-04 §05 and (3) of 10-03 §05. Below, each step is given with "what it uses" and its grade.

Step 0 The premise rows

That the measure μ\mu with T=∞T=\infty is uniquely determined (simplicity of the principal eigenvalue, from the positivity of the integral kernel of the transfer operator) Assumption (the original source for the version with a positive kernel on R\mathbb R has not been checked; the same row as in 10-04 §01). The relation between CP(T)C_P(T) of the finite ring and CPC_P of the measure with T=∞T=\infty (the step of the limit), and the regularity of the functions used in the steps below (conditional measures, smoothness of the kink coordinates) Assumption. These three are premises placed outside Proposition 4.5, and they are counted as assumption rows in the integrated table (10-12) too.

Step 1 Reduction to the box — condition (H3) in the form of Proposition H3

Cover the line Z\mathbb Z by boxes of length LL sites. Neighbouring boxes overlap in ll sites (l≤L/3l\le L/3), and the boxes are divided alternately into an even family EE and an odd family OO. Let GE\mathcal G_E be the σ\sigma-algebra generated by the values at the sites outside the even family, define GO\mathcal G_O in the same way, and let the maximal correlation of the two σ\sigma-algebras be

calt:=sup⁡{corr⁡μ(F,G): F∈L2(GE), G∈L2(GO)}(6)c_{\rm alt}:=\sup\bigl\{\operatorname{corr}_\mu(F,G):\ F\in L^2(\mathcal G_E),\ G\in L^2(\mathcal G_O)\bigr\} \tag{6}

.

Lemma TP (two projections). If c=c(G1,G2)<1c=c(\mathcal G_1,\mathcal G_2)\lt1, then for all f∈L2(μ)f\in L^2(\mu), Var⁡f≤(1−c)−1(EVar⁡(f∣G1)+EVar⁡(f∣G2))\operatorname{Var}f\le(1-c)^{-1}\bigl(\mathbb E\operatorname{Var}(f\mid\mathcal G_1)+\mathbb E\operatorname{Var}(f\mid\mathcal G_2)\bigr).

Proved here Proof. Put f~=f−Ef\tilde f=f-\mathbb Ef and ai=E[f∣Gi]−Efa_i=\mathbb E[f\mid\mathcal G_i]-\mathbb Ef. Then s:=∥a1∥2+∥a2∥2=⟨f~,a1+a2⟩≤∥f~∥ ∥a1+a2∥s:=\|a_1\|^2+\|a_2\|^2=\langle\tilde f,a_1+a_2\rangle\le\|\tilde f\|\,\|a_1+a_2\|, while ∥a1+a2∥2≤s+2c∥a1∥∥a2∥≤(1+c)s\|a_1+a_2\|^2\le s+2c\|a_1\|\|a_2\|\le(1+c)s. Hence s≤(1+c)∥f~∥2s\le(1+c)\|\tilde f\|^2, and adding EVar⁡(f∣Gi)=∥f~∥2−∥ai∥2\mathbb E\operatorname{Var}(f\mid\mathcal G_i)=\|\tilde f\|^2-\|a_i\|^2 gives at least (1−c)∥f~∥2(1-c)\|\tilde f\|^2. ∎ Leantwo_proj_var (assumption: A+B≤(1+c)VA+B\le(1+c)V. The geometry of the projections is outside Lean).

The product over boxes. Even boxes are L−2l≥1L-2l\ge1 sites apart, so by the Markov property of the nearest-neighbour interaction they are mutually independent under GE\mathcal G_E. The variance of a function of independent components is at most the sum of the conditional variances component by component (of the Efron–Stein type), so

EVar⁡(f∣GE) ≤ Cbox(L)∑B∈EEB(f)(7)\mathbb E\operatorname{Var}(f\mid\mathcal G_E)\ \le\ C_{\rm box}(L)\sum_{B\in E}\mathcal E_B(f) \tag{7}

holds Proved here (the Markov property and the variance inequality for independent products; the proof is placed in 10-11). The same holds for the odd family. Each site lies in the even family at most once and in the odd family at most once, and only the overlaps lie in both.

Averaging over shifts. Shift the arrangement of boxes by ll at a time, in n=⌊(L−l)/l⌋n=\lfloor(L-l)/l\rfloor ways. Every shift has the same caltc_{\rm alt}, and the overlap sites are disjoint between shifts. Applying Lemma TP and (7) to each shift and averaging gives

CP(μ) ≤ (1+1n)Cbox(L)1−calt(8)C_P(\mu)\ \le\ \Bigl(1+\frac1n\Bigr)\frac{C_{\rm box}(L)}{1-c_{\rm alt}} \tag{8}

Proved here Leanbox_two_family, box_shift_average (assumptions: the two-family inequality for each shift, Cbox≥0C_{\rm box}\ge0, the sum of the forms on the overlaps at most E\mathcal E). This is Proposition H3, and cMc_M of (H3) corresponds to (1−calt)/(1+1/n)(1-c_{\rm alt})/(1+1/n). This step uses only Poincaré inequalities, not the logarithmic Sobolev inequality.

One assumption row remains in (8): that the alternating maximal correlation calt<1c_{\rm alt}\lt1 is uniform in ℏ\hbar (row (MIXalt)). Its value is read as calt≈0.73c_{\rm alt}\approx0.73 at C=2C=2 and overlap θ=l/L=14\theta=l/L=\tfrac14 Reading (a family value copied from the closed formula for the two-state telegraph chain; not a proof of an upper bound). The type of the reduction to the box has the same form as the box dynamics for Glauber dynamics of discrete spins (Propositions 3.4 and 3.5 of Martinelli's lectures) Cited (discrete spins, in the form of a total-variation coupling; here rewritten in one dimension, in L2L^2, in the form of maximal correlation).

Step 2 Inside the box — condition (H4) in the form of Proposition H4, and where (H1)(H2) enter

Fix a box BB (Lε=CξL\varepsilon=C\xi) and boundary values (a,b)(a,b). Let the slow variable inside the box be YY = the arrangement of kinks (the number of kinks, and the position of each kink defined by projection onto the manifold of kinks). Splitting the variance by YY gives

Var⁡f=EVar⁡(f∣Y)+Var⁡(E[f∣Y])(9)\operatorname{Var}f=\mathbb E\operatorname{Var}(f\mid Y)+\operatorname{Var}\bigl(\mathbb E[f\mid Y]\bigr) \tag{9}

Proved here (the identity for conditional expectations).

First term = the fast side. (H1) and (H2) enter here. By the nearest-neighbour Markov property, the conditional measure with YY fixed splits into a product of the following parts. (i) Scraps of the phase without kinks between kinks (length ≤Cξ\le C\xi, with values at both ends). (ii) The tube around each kink or kink pair, and the core inside it (the interval that stays near the top). The Poincaré constant of a product measure is the maximum of the constants of the components (the variance inequality for independent products), so

EVar⁡(f∣Y) ≤ Cloc E(f),Cloc=max⁡(C(H1seg), C(H2tube), C(T0P′))(10)\mathbb E\operatorname{Var}(f\mid Y)\ \le\ C_{\rm loc}\,\mathcal E(f),\qquad C_{\rm loc}=\max\bigl(C_{\rm (H1^{seg})},\ C_{\rm (H2^{tube})},\ C_{\rm (T0'_P)}\bigr) \tag{10}

Proved here (the Poincaré constant of a product measure is the maximum of the constants of the components. That it splits into a product depends on how YY is defined, and its regularity is included in the row of Step 0). The constant of (i) is the scrap version of condition (H1), and the constants of (ii) are the tube and core rows of condition (H2) Assumption (all three are assumption rows).

Second term = the slow side. Longitudinal transport along the family of saddles enters here. E[f∣Y]\mathbb E[f\mid Y] is a function of YY alone, and its fluctuations relax by the diffusion of kink positions and by the creation and annihilation of kink pairs. The Dirichlet form EY\mathcal E_Y on YY has mobility per kink of the form D=ℏ/S0D=\hbar/S_0 (row (Mob): the projection formula, 10-04 §03). Here we put two rows.

ckgc_{\rm kg} of (KG) comes from reading in the continuum limit the closed formula for the gap of the Glauber box with fixed ends, (1−γ)+γ(1−cos⁡(π/(L+1)))(1-\gamma)+\gamma(1-\cos(\pi/(L+1))),

Dξ2+π2DLτ2=(C2+π2)D(Cξ)2(Lτ=Cξ)(11)\frac{D}{\xi^2}+\frac{\pi^2D}{L_\tau^2}=\bigl(C^2+\pi^2\bigr)\frac{D}{(C\xi)^2}\qquad(L_\tau=C\xi) \tag{11}

which gives ckg=C2+π2c_{\rm kg}=C^2+\pi^2 Proved here (the algebra of (11)) Leankg_constant (assumption: Cξ≠0C\xi\ne0). The first term D/ξ2D/\xi^2 is the creation and annihilation of pairs, and the second is the diffusion of kink positions. When a boundary value is near the top, half a kink can sit at the end of the box (corresponding to a free end), and in the sup⁡\sup including that case ckg=cff(C)c_{\rm kg}=c_{\rm ff}(C), read as 7.177.17 at C=2C=2 Reading (a family value obtained from lattice values of the gap of the free-end box of the one-dimensional Ising model).

Combining (9)(10) with (KG)(X) gives

Cbox ≤ Cloc+(1+χ) Ckg ≤ K4 (Cξ)2D,K4=1+χckg(1−ηKG)+Cloc D(Cξ)2(12)C_{\rm box}\ \le\ C_{\rm loc}+(1+\chi)\,C_{\rm kg}\ \le\ K_4\,\frac{(C\xi)^2}{D},\qquad K_4=\frac{1+\chi}{c_{\rm kg}(1-\eta_{\rm KG})}+C_{\rm loc}\,\frac{D}{(C\xi)^2} \tag{12}

Proved here LeanH4_two_scale (assumptions: the inequality of decomposition (9), first term ≤ClocE\le C_{\rm loc}\mathcal E, (KG) ≤CkgEY\le C_{\rm kg}\mathcal E_Y, (X), Ckg≥0C_{\rm kg}\ge0), H4_gap_form (assumptions: D>0D\gt0, Cξ≠0C\xi\ne0, ckg>0c_{\rm kg}\gt0, ηKG<1\eta_{\rm KG}\lt1, 1+χ≥01+\chi\ge0, the two inequalities above). This is Proposition H4.

The second term of K4K_4 is ClocC_{\rm loc} multiplied by D/(Cξ)2D/(C\xi)^2, and D/ξ2=ℏ/(S0ξ2)D/\xi^2=\hbar/(S_0\xi^2) is of size e−441.6/e−1328.6/e−4433.1e^{-441.6}/e^{-1328.6}/e^{-4433.1} at the three values of ℏ\hbar (ℏ=3⋅10−3/10−3/3⋅10−4\hbar=3\cdot10^{-3}/10^{-3}/3\cdot10^{-4}) Reading (Table 2 of 10-04 §07). Unless ClocC_{\rm loc} grows exponentially in ℏ\hbar, this term vanishes as ℏ→0\hbar\to0. In this sense the demand of (H1) for Cloc=O(1)C_{\rm loc}=O(1) is a demand with room to spare.

A note on where (H2) goes. In the two-valley split of §01, (H2) was the mean-difference constant CmdC_{\rm md} itself. In the box split, the direction along the family of saddles (the kink positions) was taken as the slow variable YY, so transport in that direction is handled by (KG) and (X) of the second term, and what remains in (H2) is the Poincaré of the tube and the core with YY fixed. In this book the tube and core rows are counted as rows of (H2), and (KG)(X) as rows of (H4) (the same counting as the integrated table, 10-12).

Step 3 Composition — CP≤Kξ2S0/ℏC_P\le K\xi^2S_0/\hbar

Putting (12) into CboxC_{\rm box} of (8) and using Lε=CξL\varepsilon=C\xi and D=ℏ/S0D=\hbar/S_0 gives

CP(μ) ≤ K ξ2 S0ℏ,K=(1+1n)C2K41−calt(13)C_P(\mu)\ \le\ K\,\xi^2\,\frac{S_0}{\hbar},\qquad K=\Bigl(1+\frac1n\Bigr)\frac{C^2K_4}{1-c_{\rm alt}} \tag{13}

Proved here LeanH3_H4_compose (assumptions: the conclusion (8) of Proposition H3, the conclusion Cbox≤K4(Cξ)2/DC_{\rm box}\le K_4(C\xi)^2/D of Proposition H4, D=ℏ/S0D=\hbar/S_0, n>0n\gt0, ℏ>0\hbar\gt0, S0>0S_0\gt0, calt<1c_{\rm alt}\lt1). That KK does not depend on ℏ\hbar is the uniformity of caltc_{\rm alt}, χ\chi, ηKG\eta_{\rm KG}, ckgc_{\rm kg} and ClocC_{\rm loc}, that is, the very content of the assumption rows.

Putting in the values of the reduced model (χ=ηKG=0\chi=\eta_{\rm KG}=0, n=3n=3, θ=14\theta=\tfrac14) gives K≈2.76K\approx2.76 at C=2C=2 (the sup⁡\sup including boundary values at the top), 1.431.43 (ends on the well side only), and K≈1.78K\approx1.78 at C=4C=4 Reading (family values, not upper bounds on KK) LeanK_ff_C2, K_ff_C4 (assumptions: the measured values of cffc_{\rm ff} and caltc_{\rm alt}; arithmetic only). The value is the same at the three values of ℏ\hbar because ℏ\hbar does not enter the reduced model.

Step 4 Squeezing the ratio RR — 1≤R≤K′/ℏ1\le R\le K'/\hbar

Dividing (13) by ξ2\xi^2 gives R=CP/ξ2≤KS0/ℏ=:K′/ℏR=C_P/\xi^2\le KS_0/\hbar=:K'/\hbar Proved here (division). From below, Proposition L (10-04 §04) gives R≥1R\ge1 Proved here (continuous time, T→∞T\to\infty; the proof is placed in 10-04). Together,

1 ≤ R ≤ K′ℏ,K′=KS0(14)1\ \le\ R\ \le\ \frac{K'}{\hbar},\qquad K'=KS_0 \tag{14}

. Proposition L is a lower bound that uses no conditions, and the left inequality of (14) does not depend on (H1)–(H4).

Step 5 The power form of H — ln⁡CP/ln⁡ξ→2\ln C_P/\ln\xi\to2

ln⁡CP/ln⁡ξ=2+ln⁡R/ln⁡ξ\ln C_P/\ln\xi=2+\ln R/\ln\xi, and (14) gives 0≤ln⁡R≤ln⁡K′+ln⁡(1/ℏ)0\le\ln R\le\ln K'+\ln(1/\hbar). The remaining input is how the ruler grows, ln⁡ξ≥s/ℏ\ln\xi\ge s/\hbar (for some s>0s\gt0 and small ℏ\hbar), which comes from ξ∝ℏ1/2eS0/ℏ\xi\propto\hbar^{1/2}e^{S_0/\hbar}. The semiclassical leading term of the continuum model is a copy of a known formula Cited, and for the lattice model it is a reading that ln⁡ξ−S0lat/ℏ−12ln⁡ℏ\ln\xi-S_0^{\rm lat}/\hbar-\tfrac12\ln\hbar settles to a constant, −0.774/−0.777/−0.778-0.774/-0.777/-0.778, at the three values of ℏ\hbar Reading (10-04 §07). On this input

0 ≤ ln⁡Rln⁡ξ ≤ ℏ(ln⁡K′+ln⁡(1/ℏ))s ⟶ 0(ℏ→0)(15)0\ \le\ \frac{\ln R}{\ln\xi}\ \le\ \frac{\hbar\bigl(\ln K'+\ln(1/\hbar)\bigr)}{s}\ \longrightarrow\ 0\qquad(\hbar\to0) \tag{15}

and the power form of H follows Proved here Leanpower_H_of_kink_ratio (assumptions: 0<K0\lt K, 0<s0\lt s, 0<δ0\lt\delta, and 1≤R≤K/ℏ1\le R\le K/\hbar and s/ℏ≤ln⁡ξs/\hbar\le\ln\xi for 0<ℏ<δ0\lt\hbar\lt\delta. KK in Lean is K′K' in the text).

Checking the single line

Shrinking Steps 1–5 to one line gives

(H1seg), (H2tube), (T0P′)⏟Cloc → (9)(10), (KG), (X)  Cbox≤K4(Cξ)2D⏟Proposition H4 → Proposition H3, (MIXalt)  CP≤Kξ2S0ℏ → Proposition L  1≤R≤K′ℏ → ln⁡ξ≥s/ℏ  power form of H(16)\underbrace{\mathrm{(H1^{seg})},\ \mathrm{(H2^{tube})},\ \mathrm{(T0'_P)}}_{C_{\rm loc}}\ \xrightarrow{\ (9)(10),\ \mathrm{(KG)},\ \mathrm{(X)}\ }\ \underbrace{C_{\rm box}\le K_4\tfrac{(C\xi)^2}{D}}_{\text{Proposition H4}}\ \xrightarrow{\ \text{Proposition H3},\ \mathrm{(MIX_{alt})}\ }\ C_P\le K\tfrac{\xi^2S_0}{\hbar}\ \xrightarrow{\ \text{Proposition L}\ }\ 1\le R\le\tfrac{K'}{\hbar}\ \xrightarrow{\ \ln\xi\ge s/\hbar\ }\ \text{power form of H} \tag{16}

. Of the inputs written above the arrows, the assumption rows are (H1seg), (H2tube), (T0′P), (KG), (X), (MIXalt) and the premises of Step 0, and the rest are elementary algebra, known theorems or readings.

Here we also check that the statements of the assumption rows do not contain the quantities of the conclusion. The quantities of the conclusion are CP(μ)C_P(\mu) of the whole measure with T=∞T=\infty and the ratio RR. (H1seg), (H2tube) and (T0′P) are constants of the measures of scraps, tubes and cores, (KG) is a constant of the reduced gas, (X) is a comparison of forms, and (MIXalt) is a quantity of correlation. None of them contains CP(μ)C_P(\mu) or RR. A form that puts the conclusion among the premises (a circle of dependence) does not appear in the way these steps are built (for how to check this, see 10-13).

To be precise, the conclusion of Proposition 4.5 is the first-step statement that "the relaxation time CPC_P of Langevin dynamics grows as a power of ξ2\xi^2". CPC_P is a different quantity from the gap of the transfer operator (the tunnelling splitting), and even if every row of Proposition 4.5 were in place, the statements from the second step on would not follow (10-01 §08, 10-03 §06).

05

The distance from known theorems

Within the range searched, no known theorem gives the upper bound (5) of Proposition 4.5. Table 1 summarises how far nearby theorems reach and where they stop.

Table 1 Where known theorems reach and where they do not (the grade is the grade of the row that cites the theorem)
Known theoremWhere it reachesWhere it does notGrade
The Poincaré version of Eyring–Kramers (Bovier–Gayrard–Klein; Menz–Schlichting Lemma 2.4, Theorems 2.9 and 2.12)For a Morse function at fixed dimension, from the splitting of the variance, local Poincaré and transport of the mean difference up to the asymptotics of the gap and the prefactorThe constants are not uniform in the dimension. Degenerate families of saddles such as translation of a kink are outside the assumptionsCited
Eyring–Kramers for the stochastic Allen–Cahn equation on a fixed interval (Di Gesù–Le Peutrec; Brooks–Di Gesù)Asymptotics of the gap with the length of the interval fixed below the bifurcation thresholdThe regime with infinite interval length and the translation family are stated by the authors themselves in the text to be out of scopeCited
Transition times of short paths (Berglund–Gentz Theorem 2.6)The mean time to move between valleys for T<2π2T\lt2\pi\sqrt2 (uniform saddle)Long paths (T≫ξT\gg\xi)Cited
Diffusion of a single interface (Bertini–Brassesco–Buttà Theorem 2.1)That the position of a single kink approaches Brownian motion with diffusion coefficient DD (at the level of the process)Not a statement about the spectral gap of the whole pathCited
A criterion uniform in the volume (Bauerschmidt–Dagallier Theorem 2.1)Applies directly to the lattice of paths and gives an upper bound uniform in the volumeThe value is CP≤ecξC_P\le e^{c\xi} with c≈1.4→1.8c\approx1.4\to1.8 (ε=0.25\varepsilon=0.25, ℏ=0.4→0.1\hbar=0.4\to0.1), doubly exponential in ℏ\hbar. It does not reach the power form of HCited (theorem) Reading (value)
Box dynamics (Propositions 3.4 and 3.5 of Martinelli's lectures)For discrete spins, the type that controls the whole gap by the box dynamics and the gap inside the boxUnbounded spins, sup⁡\sup over boundary values. Step 1 borrows only the type, rewritten in one dimension in the L2L^2 formCited (type)

As the last three rows of Table 1 show, the known tools sit at the two ends, "a single kink" and "an upper bound uniform in the volume but coarse", and what lies between them (an upper bound on long paths sharp up to the diffusion time ξ2/D\xi^2/D of the kink gas) is the place of Proposition 4.5. The Bauerschmidt–Dagallier bound becoming ecξe^{c\xi} is read as follows: the criterion looks at a single quantity, the susceptibility, so it cannot distinguish slow but local relaxation from slow and global relaxation, and ξ\xi enters the exponent Reading.

06

The table of the five grades — the rows of the steps of Proposition 4.5

We put the steps of §04 into one table in the format of the five grades (10-00 §01). Each row has one grade, and the column of machine checking is outside the grades. The symbols of the rows correspond to the numbers of the nodes of the dependency graph in §07.

Table 2 The rows of the steps of Proposition 4.5 ("—" in the range of ℏ\hbar marks an assumption row not shown at any ℏ\hbar)
RowStatement (one line)GradeGroundsRange of ℏ\hbarMachine checking
P0Uniqueness of the measure with T=∞T=\infty, the step of the limit, regularityAssumption§04 Step 0 (the original source for the principal eigenvalue of a positive kernel on R\mathbb R is unchecked)——
H1s(H1seg) Poincaré of scraps without kinks uniform in the length, the end values and ℏ\hbarAssumption§03, (10) of §04 Step 2. The node propositions for the ring version are in 10-06——
H2t(H2tube) Poincaré of the tube uniform in length ≤Cξ\le C\xiAssumption§03, (10)——
T0P(T0′P) Poincaré of the core uniform in the core lengthAssumption§03, (10). The proposition with an assumption at the lower end of the window is in 10-09 and 10-11——
KG(KG) The box gap of the reduced kink gas ≥ckg(1−ηKG)D/(Cξ)2\ge c_{\rm kg}(1-\eta_{\rm KG})D/(C\xi)^2Assumption§04 Step 2 (the assumption that it falls into the Glauber type)——
X(X) Cross term EY(E[f∣Y])≤(1+χ)E(f)\mathcal E_Y(\mathbb E[f\mid Y])\le(1+\chi)\mathcal E(f)Assumption§04 Step 2——
MIX(MIXalt) calt<1c_{\rm alt}\lt1 uniformly in ℏ\hbarAssumption§04 Step 1——
MobMobility of a single kink D=ℏ/S0D=\hbar/S_0Cited§02 (d), 10-04 §03 (a copy of the coefficient of a theorem at the level of the process)ℏ→0\hbar\to0—
TPLemma TP (two projections)Proved hereProof in §04 Step 1Independent of ℏ\hbartwo_proj_var (assumption: A+B≤(1+c)VA+B\le(1+c)V)
ESConditional independence of even boxes and the product variance inequality (7)Proved here§04 Step 1 (proof in 10-11)Independent of ℏ\hbar—
H3Proposition H3: (8) CP≤(1+1/n)Cbox/(1−calt)C_P\le(1+1/n)C_{\rm box}/(1-c_{\rm alt})Proved here§04 Step 1 (TP, ES, averaging over shifts)Independent of ℏ\hbarbox_two_family, box_shift_average (assumptions: two-family inequality, Cbox≥0C_{\rm box}\ge0, sum over overlaps ≤E\le\mathcal E)
DECDecomposition of the variance (9) and into a product (10)Proved here§04 Step 2 (the product decomposition depends on how YY is defined; regularity is in P0)Independent of ℏ\hbar—
KGcckg=C2+π2c_{\rm kg}=C^2+\pi^2 (the algebra of (11))Proved here§04 Step 2 (the closed Glauber formula is inside (KG))Independent of ℏ\hbarkg_constant (assumption: Cξ≠0C\xi\ne0)
H4Proposition H4: (12) Cbox≤K4(Cξ)2/DC_{\rm box}\le K_4(C\xi)^2/DProved here§04 Step 2Independent of ℏ\hbarH4_two_scale, H4_gap_form (assumptions are the rows of §04 Step 2)
P45Proposition 4.5: (13) CP≤Kξ2S0/ℏC_P\le K\xi^2S_0/\hbarProved here§04 Step 3ℏ→0\hbar\to0H3_H4_compose (assumptions: (8), (12), D=ℏ/S0D=\hbar/S_0, n,ℏ,S0>0n,\hbar,S_0\gt0, calt<1c_{\rm alt}\lt1)
KvK≈2.76/1.43K\approx2.76/1.43 (C=2C=2), 1.781.78 (C=4C=4)Reading§04 Step 3 (reduced model, χ=ηKG=0\chi=\eta_{\rm KG}=0, family values)Independent of ℏ\hbarK_ff_C2, K_ff_C4 (assumptions: measured values; arithmetic only)
LProposition L: R≥1R\ge1Proved here10-04 §04Every ℏ\hbarlocal_rayleigh_ratio_le_one (the skeleton of the finite sum only; the assumptions are in Table 3 of 10-04)
Rb(14) 1≤R≤K′/ℏ1\le R\le K'/\hbarProved here§04 Step 4ℏ→0\hbar\to0—
Xiln⁡ξ≥s/ℏ\ln\xi\ge s/\hbar (ξ∝ℏ1/2eS0/ℏ\xi\propto\hbar^{1/2}e^{S_0/\hbar})Reading§04 Step 5 (the continuum leading term is Cited, the values of the lattice model are Reading)Read at three points; ℏ→0\hbar\to0 from the leading term—
PHThe power form of H: ln⁡CP/ln⁡ξ→2\ln C_P/\ln\xi\to2Proved here(15) of §04 Step 5ℏ→0\hbar\to0power_H_of_kink_ratio (assumptions: 0<K,s,δ0\lt K,s,\delta, 1≤R≤K/ℏ1\le R\le K/\hbar, s/ℏ≤ln⁡ξs/\hbar\le\ln\xi)

The "Proved here" rows of Table 2 are all algebra that takes assumption rows as input. That "Proved here" rows line up does not mean that the conclusion of Proposition 4.5 has been shown. The conclusion becomes unconditional only when every "Assumption" row and the "Reading" row (Xi) have been replaced.

07

The dependency graph — checking by the numbers that there is no circle

We turn the rows of Table 2 into a list of numbered nodes. The format is common to this part (the integrated graph of 10-12 is the same), and the numbers of the premises to the right of "⟸" are always placed smaller than the number of the conclusion on the left. The leaves (assumptions, known results, readings) have small numbers, and the conclusion has the largest number.

[01] ASM P0        uniqueness of the T=∞ measure, limit step, regularity     ħ: —
[02] ASM (H1seg)   Poincaré of scraps without kinks                         ħ: —
[03] ASM (H2tube)  Poincaré of the tube (length ≤ Cξ)                       ħ: —
[04] ASM (T0'P)    Poincaré of the core (uniform in core length)            ħ: —
[05] ASM (KG)      box gap of the reduced kink gas                          ħ: —
[06] ASM (X)       cross term ℰ_Y ≤ (1+χ)ℰ                                  ħ: —
[07] ASM (MIXalt)  alternating maximal correlation c_alt < 1               ħ: —
[08] CIT Mob       mobility of a single kink D = ħ/S₀                       ħ→0
[09] RDG Xi        ln ξ ≥ s/ħ (ξ ∝ ħ^½ e^(S₀/ħ))                            three points, leading term
[10] PRV TP        lemma of two projections                                 independent of ħ
                   Lean two_proj_var (assumption: A+B ≤ (1+c)V)
[11] PRV ES        conditional independence of even boxes, product variance (7) ⟸ [01]   independent of ħ
[12] PRV DEC       decomposition of variance (9), into a product (10) ⟸ [01]   independent of ħ
[13] PRV KGc       c_kg = C²+π² (algebra of (11))                           independent of ħ
                   Lean kg_constant (assumption: Cξ ≠ 0)
[14] PRV Prop H3   (8) ⟸ [07][10][11]                                       independent of ħ
                   Lean box_two_family, box_shift_average (assumptions: two-family inequality, C_box ≥ 0, sum over overlaps ≤ ℰ)
[15] PRV Prop H4   (12) ⟸ [02][03][04][05][06][08][12][13]                  independent of ħ
                   Lean H4_two_scale, H4_gap_form (assumptions: decomposition, C_loc, (KG), (X), D > 0, η < 1 and others)
[16] PRV Prop 4.5  (13) C_P ≤ Kξ²S₀/ħ ⟸ [08][14][15]                        ħ→0
                   Lean H3_H4_compose (assumptions: (8), (12), D = ħ/S₀, n, ħ, S₀ > 0, c_alt < 1)
[17] PRV Prop L    R ≥ 1 ⟸ [01]                                             every ħ
                   Lean local_rayleigh_ratio_le_one (skeleton of the finite sum only)
[18] PRV (14)      1 ≤ R ≤ K'/ħ ⟸ [16][17]                                  ħ→0
[19] PRV power H   ln C_P / ln ξ → 2 ⟸ [09][18]                             ħ→0
                   Lean power_H_of_kink_ratio (assumptions: 0 < K, s, δ; 1 ≤ R ≤ K/ħ; s/ħ ≤ ln ξ)

How to check. In every row with "⟸", look to see that the numbers on the right are smaller than the number on the left. [11] and [12] use only [01], [14] uses [07][10][11], [15] uses [02]–[06][08][12][13], [16] uses [08][14][15], [17] uses [01], [18] uses [16][17], and [19] uses [09][18]. Every row keeps the rule. If the rule is kept, following the premises always lowers the number and eventually reaches a leaf, so there is no circle.

Among the leaves, "Assumption" covers the seven [01]–[07], "Cited" is [08], and "Reading" is [09]. The conclusion [16] of Proposition 4.5 depends on all of [01]–[08] (on [01] also through [11][12]), and the power form of H [19] depends further on [09]. Only Proposition L [17] depends on nothing but [01] and does not use (H1)–(H4).

To be precise, this graph is the dependency of the construction of the steps of Proposition 4.5, and it does not include the content of each assumption row (for example Proposition H1, which supports [02] at the nodes). Those are in the graphs of the chapters on each condition, and the graph that joins them all into one is the integrated graph of 10-12.

08

A ℏ\hbar that fits all, and where the four conditions stand

There is no ℏ\hbar at which all rows are in place. The node propositions of condition (H1) are at six points with ℏ≥0.005\hbar\ge0.005, the conditional propositions that support the core row are at the lower end of the window, of order ℏ≤10−3\hbar\le10^{-3}, and the two do not meet. (KG), (X) and (H2tube) are assumption rows at every ℏ\hbar. The band figure and the way of fitting them together are placed in 10-12.

We list where each of the four conditions stands, one line each. The details are in each chapter.

Where the four conditions stand
  1. Condition (H1) — Proposition H1 for the ring version: margin ≥0.067\ge0.067 at the six nodes ℏ∈{0.2,0.1,0.05,0.02,0.01,0.005}\hbar\in\{0.2,0.1,0.05,0.02,0.01,0.005\}, with neighbours and ends in [0,2.5][0,2.5] (computer-assisted). What remains is between the nodes, ℏ<0.005\hbar\lt0.005, ends >2.5\gt2.5, and the scrap version (10-06)
  2. Condition (H2) — a map split into seven routes. The condition on the chain outside the window is computer-assisted on the whole window [3⋅10−4,3⋅10−3][3\cdot10^{-4},3\cdot10^{-3}], five steps of the sector framework are propositions, and for the one remaining proposition three strands stop at the curvature shortfall 14\tfrac14 at one site at the top (10-07–10-10)
  3. Condition (H3) — Proposition H3 (§04 Step 1). (MIXalt) and the sup⁡\sup over boundary values remain (10-11)
  4. Condition (H4) — Proposition H4 (§04 Step 2). (X), (KG), (H1seg) and the core row remain, and the core constant is controlled in three steps (10-11)

This part is a study that chose Assumption H as its foothold, and Proposition 4.5 is one way of splitting to build the upper side of the first step. Other views are treated in Part 11.


What this chapter can say

What is saidWhat is not said
Proved here The algebra of the splitting of the variance (3), Lemma TP, Proposition H3 (8), Proposition H4 (12), the composition (13), the squeeze of the ratio (14), the algebra to the power form of H (15). All are algebra on named assumption rows Lean (the assumptions are the rows of Table 2)None of the assumption rows [01]–[07]. Hence neither (5) itself nor the power form of H for the first step
Proved here Proposition L: R≥1R\ge1 (uses no conditions)Whether RR grows like 1/ℏ1/\hbar or exponentially
Cited The diffusion coefficient of a single kink; how far known theorems reach (Table 1)A known theorem giving an upper bound on long paths sharp up to the diffusion time of the kink gas (only as far as "not found within the range searched")
Reading K≈2.76K\approx2.76 and others (reduced model), calt≈0.73c_{\rm alt}\approx0.73, how ln⁡ξ\ln\xi growsUsing these in proofs of upper or lower bounds
That the dependency graph has no circle (the rule of the numbers)A ℏ\hbar at which all rows are in place. Implications from the first step to the second and later steps

Sources and reproduction

ItemKindSource / tools
The splitting of the variance, the skeleton of the Poincaré version of Eyring–KramersCitedG. Menz, A. Schlichting, Ann. Probab. 42 (2014), arXiv:1202.1510 (Lemma 2.4, Theorems 2.9 and 2.12; text checked). A. Bovier, V. Gayrard, M. Klein, J. Eur. Math. Soc. 7 (2005) 69–99 (bibliographic data).
Bakry–Émery on a convex regionCitedD. Bakry, M. Émery, LNM 1123 (1985); A. V. Kolesnikov, E. Milman, J. Geom. Anal. 27 (2017), arXiv:1310.2526 (Theorem 1.2; text checked).
Eyring–Kramers on a fixed intervalCitedG. Di Gesù, D. Le Peutrec, arXiv:1506.04434 (Theorem 1.1); M. Brooks, G. Di Gesù, arXiv:2606.16083 (the explicit statement of what is out of scope; text checked).
Transition times of short paths, diffusion of a single interfaceCitedThe table of sources of 10-04 (Berglund–Gentz, Bertini–Brassesco–Buttà).
A criterion uniform in the volumeCited, ReadingR. Bauerschmidt, B. Dagallier, Comm. Pure Appl. Math. 77, arXiv:2202.02295 (Theorem 2.1; text checked). The application to the lattice of paths and the value ecξe^{c\xi} are floating-point computations of the record (transfer matrix, ε=0.25\varepsilon=0.25, 1.0049 on the harmonic positive control).
The type of box dynamicsCitedF. Martinelli, LNM 1717 (1999) 93–191 (checked in §3.6 and Propositions 3.4 and 3.5 of the preprint).
The lemma of two projections, the Efron–Stein typeProved here§04 Step 1 of the text (the original sources for the Friedrichs angle and Efron–Stein are bibliographic only).
The closed formula for the box gap of Glauber dynamics, values with free endsAssumption, ReadingR. J. Glauber, J. Math. Phys. 4 (1963) 294 (bibliographic only). The fixed-end formula agrees to 6 digits with diagonalisation over all states of small chains; free ends are lattice values (floating point).
Values of the alternating maximal correlationReadingFamily values copied from the closed formula for the two-state telegraph chain (floating point).
The algebra of the stepsProved here, LeanTheorems split_poincare_le, reduced_two_state_value, two_proj_var, box_two_family, box_shift_average, kg_constant, H4_two_scale, H4_gap_form, H3_H4_compose, K_ff_C2, K_ff_C4, power_H_of_kink_ratio (the assumptions are the rows of Table 2 and of the text). The list of statements is in 10-13.

Words used in this chapter — splitting of the variance, local Poincaré, transport of the mean difference, conditions (H1)–(H4), Proposition 4.5, phase (phase without kinks), scrap, tube, core, box dynamics (reduction to the box), maximal correlation, alternating maximal correlation, lemma of two projections, Efron–Stein inequality, reduced kink gas, cross term, dependency graph. Their meanings are in A-02 Glossary.

Next chapter to read: 10-06 (H1) Local Poincaré within a phase — turns the Poincaré constant of the measure of the phase without kinks into node propositions at six values of ℏ\hbar, by a two-scale construction of kept sites and bridges, and describes the method and cost of filling in between the nodes.

← 10-04 The path measure of the double well, and kinksContents10-06 (H1) Local Poincaré within a phase →

Revised 2026-10-09: first version.