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arxiv: 2508.13324 · v2 · submitted 2025-08-18 · ❄️ cond-mat.stat-mech · math-ph· math.MP

Generalized Algebra Grounded on Nonadditive Entropies

Pith reviewed 2026-05-18 21:55 UTC · model grok-4.3

classification ❄️ cond-mat.stat-mech math-phmath.MP
keywords nonadditive entropyq-algebra(q,δ)-algebraTsallis entropycomplex systemsgeneralized statistical mechanicsthermodynamic consistency
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The pith

The (q,δ)-algebra generalizes the q-algebra from the unified nonadditive entropy S_{q,δ}.

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

This paper establishes that the entropic functional S_{q,δ} unifies the S_q and S_δ cases for handling thermostatistics of complex systems with different scalings of the number of states W(N). For systems where W(N) grows as N to some power, S_q works with q adjusted accordingly, and for stretched exponential growth, S_δ is used. By combining them into S_{q,δ}, the authors define a corresponding (q,δ)-algebra that extends the deformed product of the q-algebra. A reader would care if this provides a more general tool for systems that are neither fully extensive nor standard in their phase space structure.

Core claim

The functional S_{q,δ}({p_i}) = k ∑_{i=1}^W p_i (ln_q (1/p_i))^δ unifies both S_q and S_δ, and this unification allows the definition of the (q,δ)-algebra by generalizing the q-product to a new operation that satisfies the appropriate additivity for the δ-powered q-logarithm.

What carries the argument

The (q,δ)-algebra, built around a generalized product operation that makes the δ power of the q-logarithm additive, extending the property ln_q (x ⊗_q y) = ln_q x + ln_q y of the q-algebra.

Load-bearing premise

The generalized product follows directly from the properties of S_{q,δ} in a way that preserves thermodynamic consistency for the stated classes of W(N) scaling.

What would settle it

Deriving the explicit form of the (q,δ)-product and checking whether it indeed makes S_{q,δ} extensive for a concrete system with W(N) proportional to N^ρ would test the claim.

read the original abstract

The class of $N$-body complex systems with total number of microscopic states given by $W(N) \sim \nu^{N^\gamma}\;(\nu >1, \,\gamma > 0)$ can be thermostatistically handled with the nonadditive entropic functional $S_\delta(\{p_{i}\}) = k\sum_{i=1}^W p_i \Bigl(\ln \frac{1}{p_i} \Bigr)^\delta \;(\delta>0,\,S_1=S_{BG})$, $S_{BG}=k\sum_{i=1}^W p_i \ln \frac{1}{p_i}$ being the Boltzmann-Gibbs functional. Indeed, $S_{\delta=1/\gamma}(\{1/W(N)\})=k[\ln W(N)]^{\frac{1}{\gamma}} \propto N$, as mandated by thermodynamics. Another wide class is that with $W(N) \sim N^\rho\;(\rho>0)$ and a generalized statistical mechanics grounded on the nonadditive entropic functional $S_q(\{p_{i}\})=k\sum_{i=1}^W p_i \ln_q \frac{1}{p_i} \;(q\in \mathbb{R},\;S_1=S_{BG})$, with $\ln_q z =\frac{z^{1-q}-1}{1-q}\; (z\geq0,\;q\in\mathbb{R},\;\ln_1 z=\ln z)$, satisfactorily handles such systems with $q=1-1/\rho$. Furthermore, for this class, the size of the corresponding admissible phase space is characterized by $\ln_q (x\otimes_q y) =\ln_q x + \ln_q y,\, x,y\geq1,\,q\leq 1$, and the $q$-product $x\otimes_q y=[x^{1-q}+y^{1-q}-1]^{\frac{1}{1-q}}_{+}\;(x\otimes_1 y=xy)$ also leads to the definition of a $q$-algebra. The entropic functional $S_{q,\delta}(\{p_{i}\})=k\sum_{i=1}^W p_i \Bigl(\ln_q \frac{1}{p_i} \Bigr)^\delta\;(q\in\mathbb{R},\delta>0)$ unifies both cases above: $S_{q,1}=S_q$, $S_{1,\delta}=S_\delta$ and $S_{1,1}=S_{BG}$. In this paper, we generalize the $q$-algebra associated with $S_{q}$ to a new one associated with $S_{q,\delta}$, namely the $(q,\delta)$-algebra.

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

2 major / 1 minor

Summary. The manuscript introduces the generalized entropic functional S_{q,δ}({p_i}) = k ∑ p_i (ln_q (1/p_i))^δ, which reduces to S_q when δ=1 and to S_δ when q=1, thereby unifying the two nonadditive entropies for systems whose phase-space cardinality scales as W(N)∼ν^{N^γ} or W(N)∼N^ρ. It then constructs a (q,δ)-algebra by extending the q-product through a functional equation that raises the q-logarithm to the power δ, with the goal of preserving the algebraic structure needed for thermodynamic extensivity.

Significance. If the algebraic construction is shown to enforce S_{q,δ}({1/W})∝N for the interpolated scaling class, the work would supply a single framework capable of handling both power-law and stretched-exponential growth of the number of states, thereby extending the domain of nonadditive thermostatistics without introducing new ad-hoc parameters beyond q and δ.

major comments (2)
  1. The central claim that the (q,δ)-product defined by the functional equation [ln_q (x ⊗_{q,δ} y)]^δ = [ln_q x]^δ + [ln_q y]^δ automatically yields an extensive S_{q,δ} for hybrid W(N) scalings is not accompanied by an explicit verification; the abstract states the unification but the load-bearing step—demonstrating that the resulting W(N) makes S_{q,δ} linear in N—remains unshown beyond the special cases δ=1 and q=1.
  2. The thermodynamic consistency argument relies on the prior definitions of S_q and the q-product from the authors’ earlier work; an independent check that the combined (q,δ) structure satisfies the extensivity requirement for a continuous family of W(N) interpolating between ν^{N^γ} and N^ρ is needed to avoid reducing to the two already-known limits.
minor comments (1)
  1. The abstract would benefit from an explicit statement of the functional form chosen for the (q,δ)-product and the precise class of W(N) for which extensivity is claimed.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading of our manuscript and the constructive comments. We address each major comment below and will revise the manuscript accordingly to improve its clarity and completeness.

read point-by-point responses
  1. Referee: The central claim that the (q,δ)-product defined by the functional equation [ln_q (x ⊗_{q,δ} y)]^δ = [ln_q x]^δ + [ln_q y]^δ automatically yields an extensive S_{q,δ} for hybrid W(N) scalings is not accompanied by an explicit verification; the abstract states the unification but the load-bearing step—demonstrating that the resulting W(N) makes S_{q,δ} linear in N—remains unshown beyond the special cases δ=1 and q=1.

    Authors: We thank the referee for this observation. The (q,δ)-product is introduced via the stated functional equation precisely to enforce additivity of [ln_q(·)]^δ. By this construction, S_{q,δ}({1/W}) = k [ln_q W]^δ becomes linear in N for any W(N) whose scaling makes [ln_q W(N)]^δ ∝ N, including continuous interpolations between the ν^{N^γ} and N^ρ classes. We acknowledge, however, that an explicit verification for a general hybrid family was not provided beyond the limiting cases. In the revised manuscript we will add a dedicated calculation demonstrating this property for a representative continuous family of W(N). revision: yes

  2. Referee: The thermodynamic consistency argument relies on the prior definitions of S_q and the q-product from the authors’ earlier work; an independent check that the combined (q,δ) structure satisfies the extensivity requirement for a continuous family of W(N) interpolating between ν^{N^γ} and N^ρ is needed to avoid reducing to the two already-known limits.

    Authors: We agree that an independent verification strengthens the presentation. While the (q,δ)-algebra is constructed as a direct generalization that recovers the established S_q and S_δ cases, we will include in the revision an explicit, self-contained demonstration. This will consist of selecting a smooth interpolating form for W(N) between the two scaling classes and verifying that the resulting S_{q,δ}({1/W}) remains strictly proportional to N, thereby confirming thermodynamic consistency without collapsing to the δ=1 or q=1 limits. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected in the (q,δ)-algebra generalization

full rationale

The paper introduces the unified entropic functional S_{q,δ} which explicitly reduces to the known S_q (when δ=1) and S_δ (when q=1) cases, then defines the corresponding (q,δ)-algebra by extending the functional equation for the product operation to enforce the powered additivity property on ln_q. This is a direct constructive generalization rather than a derivation that loops back to its inputs. Extensivity for the respective W(N) scalings follows from the same parameter choices already established for the special cases (δ=1/γ or q=1-1/ρ), with the new algebra constructed to preserve the analogous structure; no step equates a claimed prediction or first-principles result to a fitted parameter or self-citation by construction. The central unification claim retains independent content as a parametric extension of prior nonadditive entropy frameworks.

Axiom & Free-Parameter Ledger

2 free parameters · 2 axioms · 1 invented entities

The central claim rests on the domain assumption that the stated forms of W(N) require these specific nonadditive entropies for thermodynamic extensivity, plus standard properties of generalized logarithms; no new physical entities are postulated.

free parameters (2)
  • q
    Free parameter in the q-logarithm and entropy functional, chosen to match the scaling exponent ρ
  • δ
    Free exponent in the generalized entropy, chosen to match the scaling exponent γ
axioms (2)
  • domain assumption S_{q,δ} reduces to S_q when δ=1 and to S_δ when q=1, and satisfies thermodynamic requirements for the given W(N) classes
    Invoked in the abstract when stating unification and thermodynamic mandate
  • standard math The generalized product x ⊗_{q,δ} y satisfies ln_{q,δ}(x ⊗_{q,δ} y) = ln_{q,δ} x + ln_{q,δ} y for appropriate domains
    Assumed when extending the q-product definition to the new algebra
invented entities (1)
  • (q,δ)-algebra no independent evidence
    purpose: Algebraic structure supporting the unified entropy functional
    Newly defined in the paper; no independent evidence outside the definition itself

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