How statement and proof provenance work
The first chip identifies the source of the statement or construction; the second identifies the source of its local proof or verification.
- Literature-sourced: the exact statement appears in a cited source; only wording and notation differ.
- AI-adapted: a semantically identical restatement of literature-sourced material, modulo indexing, notation, and boundary cases adopted by the library.
- AI-generated: a genuinely novel statement formulated by AI, with no source for the claim itself.
These labels describe origin, not correctness: citations and verification chips remain separate evidence.
Continuous ideal-gas bulk limit and finite-block bridge
Statement
Assume the Axiom of Countable Choice (The Axiom of Countable Choice ()). Fix dimension , particle mass , action reference , inverse energy , and positive cube volumes with . For indistinguishable classical noninteracting particles in a cube of volume , use the phase-space reference and Hamiltonian . Define . Then the dimensionless partition integral and free-energy limits are There is also the following finite-momentum-block limit. Let , let be independent standard normal variables, set , and define canonical momenta and shell-prepared momenta . On the null event , set the shell-prepared vector to . The shell-prepared vector has exactly energy , and for every fixed and bounded continuous , This is weak convergence for each fixed block in this free-particle model. The shell preparation is the stated normalized-Gaussian construction, and no finite-width shell or interacting-gas equivalence is asserted.
Facts & Assumptions
Given: The free-particle Hamiltonian, phase-space normalization, and normalized-Gaussian shell preparation.
Assume the Axiom of Countable Choice (The Axiom of Countable Choice ()), as required by the Lebesgue-measure construction and change-of-variables suppliers below. , , , and the -particle Hamiltonian is additive kinetic energy in a cubic position box.
For the block limit, the are independent with density and is fixed while .
Under [A1], Assuming countable choice, is a sigma-algebra containing every elementary set and is a complete measure extending elementary volume makes the set function of Lebesgue measurable sets, the family , and the restricted set function a complete measure, and Lebesgue measure is sigma-finite, and every metrically bounded subset of has finite outer measure makes it sigma-finite. Assuming countable choice, every Borel subset of is Lebesgue measurable makes continuous densities and their Borel level sets measurable; A box in with parameters is Lebesgue measurable of measure , whichever of its faces are included gives the position cube its stated volume and gives singletons measure zero. Integrable real and complex functions, and their integrals defines the signed integrals used below; The Lebesgue integral is linear on makes them linear, and Monotonicity and nonnegative homogeneity of the nonnegative integral gives the nonnegative monotonicity and homogeneity used in moment and tail bounds.
The product measure of two sigma-finite measure spaces and For sigma-finite factors, the product measure exists, has the rectangle formula, is sigma-finite, and is unique: finite products of the sigma-finite Lebesgue factors carry the rectangular product measure. The Euclidean Lebesgue measure is the completion of the product of the factor Lebesgue measures identifies its completion with Euclidean Lebesgue measure, so the displayed Borel densities have the same integrals in either convention.
Tonelli's theorem for nonnegative measurable functions on a sigma-finite product and Fubini's theorem for L^1 functions on a sigma-finite product: nonnegative product integrals factor by Tonelli; integrable products may be evaluated iteratively.
The Gaussian integral : the improper Riemann Gaussian integral is . A nonnegative improper Riemann integral on a half-line agrees with the Lebesgue integral identifies each convergent nonnegative improper integral on with its Lebesgue integral. Apply it to the continuous even Gaussian and its even polynomial moments; reflection gives the negative half-line. Thus the improper integral evaluations below also evaluate their Lebesgue integrals.
A C^1 diffeomorphism satisfies the change-of-variables formula for nonnegative Lebesgue measurable functions and Square roots exist: a unique with ; the positives are : the scaling substitution is valid for , so .
The natural logarithm as the inverse of the exponential function, The natural logarithm has derivative 1/x and equals the integral from 1 to x of 1/t, and The integral logarithm is continuous and strictly increasing on : the library natural logarithm equals the integral logarithm and is strictly increasing on positive reals.
If are differentiable on with integrable, then : on each finite interval, differentiable factors with integrable derivatives obey the ordinary integration-by-parts identity.
The exponential dominates every fixed nonnegative integer power at : for each fixed nonnegative integer , by setting and bounding by a larger integer power.
Heine-Borel in : with the Euclidean metric a subset of is compact if and only if it is closed and bounded, and the proof by bisection uses no choice principle; the same holds on the real line makes each closed bounded Euclidean ball compact, and Heine-Cantor: a continuous map from a compact metric space to any metric space is uniformly continuous makes a continuous test function uniformly continuous on that ball.
Proof
Given: [A1] and, for the second conclusion, [A2].
The integrand is nonnegative, so [F3] factors the position and momentum integrals: By [F4]–[F5] the one-coordinate integral is , proving the stated exact formula with . The dimensions are consistent: is a length, so and are dimensionless.
Let have the density in [A2]. By [F4]–[F5], it is normalized. The polynomial and Gaussian factors have continuous derivatives on every finite interval, so apply [F7] on first with , , and then with , . In each case . Letting , the endpoint terms vanish by [F8], giving and . Thus and . The independence in [A2] and [F3] factor the cross integrals, so expanding the square gives For any , , so integration proves . Hence in probability.
Monotonicity of from [F6] gives , hence . Again by [F6], for , so . Substituting the exact yields Multiplication by proves the per-particle limit; multiplying by proves the per-volume limit.
Since almost surely, the shell-prepared formulas define random variables on a probability-one set. On the null event , assign the fixed shell vector ; this measurable extension leaves every expectation unchanged and has the same stated energy. On , algebra gives This exact energy constraint holds on every outcome where , an event of probability one since the joint Gaussian density assigns zero mass to the origin.
For fixed , the scalar multiplier tends to in probability by continuity at and step 1.2. Therefore tends to zero in probability: restrict first to the event , where its norm is at most , and then bound the complement by using the second moment. For bounded continuous , choose so this tail is small and additionally restrict to , whose complement has probability tending to zero. On this event both blocks lie in the ball of radius . Use uniform continuity of on the compact ball of radius , and then use convergence in probability of the difference. For any , choose by that uniform continuity. The expectation difference is at most , with the multiplier assigned arbitrarily on its null exceptional event. Sending first and then proves the claimed expectation limit.
If positions are included, choose them independently and uniformly in the same cube under both preparations. After coordinatewise rescaling by the side length, every fixed position block already has the same uniform law in both models and is independent of the momentum vector. The same bounded-continuous test argument as in 2.3, first on compact sets and then on their small tails, proves the joint fixed-block limit. This does not change the energy computation because the Hamiltonian has no position dependence.
Depends on
The Lebesgue integral is linear on
Monotonicity and nonnegative homogeneity of the nonnegative integral
The Axiom of Countable Choice ()
Assuming countable choice, is a sigma-algebra containing every elementary set and is a complete measure extending elementary volume
Lebesgue measure is sigma-finite, and every metrically bounded subset of has finite outer measure
A box in with parameters is Lebesgue measurable of measure , whichever of its faces are included
Assuming countable choice, every Borel subset of is Lebesgue measurable
The Euclidean Lebesgue measure is the completion of the product of the factor Lebesgue measures
A nonnegative improper Riemann integral on a half-line agrees with the Lebesgue integral
Heine-Borel in : with the Euclidean metric a subset of is compact if and only if it is closed and bounded, and the proof by bisection uses no choice principle; the same holds on the real line
Heine-Cantor: a continuous map from a compact metric space to any metric space is uniformly continuous
The integral logarithm is continuous and strictly increasing on
Integrable real and complex functions, and their integrals
Lebesgue measurable sets, the family , and the restricted set function
The natural logarithm as the inverse of the exponential function
The product measure of two sigma-finite measure spaces
A C^1 diffeomorphism satisfies the change-of-variables formula for nonnegative Lebesgue measurable functions
The exponential dominates every fixed nonnegative integer power at
Fubini's theorem for L^1 functions on a sigma-finite product
The Gaussian integral
If are differentiable on with integrable, then
The natural logarithm has derivative 1/x and equals the integral from 1 to x of 1/t
Square roots exist: a unique with ; the positives are
For sigma-finite factors, the product measure exists, has the rectangle formula, is sigma-finite, and is unique
Tonelli's theorem for nonnegative measurable functions on a sigma-finite product