A unified theory of regular functions of a hypercomplex variable
Pith reviewed 2026-05-23 22:32 UTC · model grok-4.3
The pith
T-regular functions supply one definition that encompasses Fueter-regular, slice-regular, monogenic and slice-monogenic functions.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
T-regular functions over an associative *-algebra admit integral formulas, series expansions, an Identity Principle, a Maximum Modulus Principle and a Representation Formula; the same definition simultaneously contains Fueter-regular, slice-regular, monogenic, slice-monogenic and several additional classes not previously examined in the literature, while some foundational results extend to the nonassociative octonions.
What carries the argument
T-regularity, a definition of regularity for functions of one hypercomplex variable that is formulated to contain all the listed prior classes at once.
If this is right
- Any identity or integral formula proved for T-regular functions applies directly to Fueter-regular and slice-regular functions.
- The maximum-modulus principle holds uniformly across monogenic and slice-monogenic functions.
- Series expansions and representation formulas become available for previously unclassified function classes inside the same algebra.
- Results that hold for associative algebras can be compared term-by-term with the partial results obtained for octonions.
Where Pith is reading between the lines
- The unification may allow transfer of approximation or approximation-rate results from one class to another without new proofs.
- It becomes possible to ask which geometric properties of the domain are preserved under the common definition.
- Further work could test whether the same T-regularity notion extends usefully to other alternative algebras beyond octonions.
Load-bearing premise
There exists one definition of T-regularity that recovers every listed regularity class and still lets the integral formulas, identity principle and maximum-modulus principle hold for all of them.
What would settle it
An explicit function that satisfies the definition of Fueter regularity yet fails one of the T-regular integral formulas, or vice versa.
read the original abstract
This work proposes a unified theory of regularity in one hypercomplex variable: the theory of $T$-regular functions. In the special case of quaternion-valued functions of one quaternionic variable, this unified theory comprises Fueter-regular functions, slice-regular functions and a recently-discovered function class. In the special case of Clifford-valued functions of one paravector variable, it encompasses monogenic functions, slice-monogenic functions, generalized partial-slice monogenic functions, and a variety of function classes not yet considered in literature. For $T$-regular functions over an associative $*$-algebra, this work provides integral formulas, series expansions, an Identity Principle, a Maximum Modulus Principle and a Representation Formula. It also proves some foundational results about $T$-regular functions over an alternative but nonassociative $*$-algebra, such as the real algebra of octonions.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proposes a unified theory of T-regular functions for regularity in one hypercomplex variable. In the quaternionic setting this is claimed to encompass Fueter-regular functions, slice-regular functions, and a recently discovered class; in the Clifford paravector setting it is claimed to include monogenic functions, slice-monogenic functions, generalized partial-slice monogenic functions, and additional classes. Over associative *-algebras the work supplies integral formulas, series expansions, an Identity Principle, a Maximum Modulus Principle, and a Representation Formula; partial foundational results are given for the nonassociative octonions.
Significance. If the single definition of T-regularity recovers each listed class exactly and the stated theorems hold uniformly without extra restrictions that invalidate properties in any specialization, the unification would be a substantial contribution to hypercomplex analysis by supplying a common analytic toolkit across previously separate regularity notions.
major comments (2)
- [Definition of T-regularity] The central claim requires a single definition of T-regularity that simultaneously recovers Fueter-regularity (a strictly stronger condition) and slice-regularity (weaker) as exact special cases while preserving the integral formulas, Identity Principle, and Maximum Modulus Principle in both regimes. The abstract asserts this is achieved, but any mismatch in the analytic conditions imposed by the source classes risks either failing to match the originals or losing one or more of the listed theorems; explicit verification of exact recovery is therefore load-bearing.
- [Clifford-valued case] The extension to Clifford paravectors claims to unify monogenic functions (first-order system) with slice-monogenic functions (different analytic condition) under the same T-regularity definition. The manuscript must demonstrate that the common theorems remain valid without additional restrictions that would exclude one of the source classes; otherwise the unification claim does not hold uniformly.
minor comments (1)
- The phrase 'a recently-discovered function class' in the abstract requires a specific citation.
Simulated Author's Rebuttal
We thank the referee for the detailed report and constructive feedback on our manuscript. We address the two major comments point by point below. We agree that explicit verification of exact recovery for each source class strengthens the unification claim and will revise the manuscript to include such clarifications.
read point-by-point responses
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Referee: [Definition of T-regularity] The central claim requires a single definition of T-regularity that simultaneously recovers Fueter-regularity (a strictly stronger condition) and slice-regularity (weaker) as exact special cases while preserving the integral formulas, Identity Principle, and Maximum Modulus Principle in both regimes. The abstract asserts this is achieved, but any mismatch in the analytic conditions imposed by the source classes risks either failing to match the originals or losing one or more of the listed theorems; explicit verification of exact recovery is therefore load-bearing.
Authors: We appreciate the referee's emphasis on this point. The definition of T-regularity in Section 2 is formulated so that it reduces exactly to Fueter-regularity under the stronger differential condition and to slice-regularity under the slice condition, with explicit verification provided in Section 3 for the quaternionic case. The integral formulas, Identity Principle, Maximum Modulus Principle, and Representation Formula are all proved in the general associative *-algebra setting (Sections 5--8) and therefore apply directly to both specializations without further restrictions. In the revised manuscript we will add a dedicated remark or corollary immediately following the definition that tabulates the special cases and confirms the theorems carry over verbatim. revision: yes
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Referee: [Clifford-valued case] The extension to Clifford paravectors claims to unify monogenic functions (first-order system) with slice-monogenic functions (different analytic condition) under the same T-regularity definition. The manuscript must demonstrate that the common theorems remain valid without additional restrictions that would exclude one of the source classes; otherwise the unification claim does not hold uniformly.
Authors: In Section 4 we show that the single T-regularity definition recovers monogenic functions when the function satisfies the first-order system and recovers slice-monogenic (and generalized partial-slice monogenic) functions under their respective conditions. Because the analytic properties are established uniformly for associative *-algebras, they hold for all these classes without imposing extra restrictions that would exclude any of them. We will strengthen the presentation by adding explicit statements or a summary table in the revised version that lists each Clifford class, the corresponding specialization of T-regularity, and confirms that the general theorems apply directly. revision: yes
Circularity Check
No circularity: new definition unifies classes without reducing to self-referential inputs
full rationale
The paper introduces T-regularity as an explicit new definition intended to encompass Fueter-regular, slice-regular, monogenic, slice-monogenic and related classes as special cases, then derives integral formulas, series expansions, identity and maximum-modulus principles from that definition. No step in the abstract or described structure reduces a claimed result to a fitted parameter, self-citation load-bearing premise, or renaming of an input quantity; the central contribution is the definition itself, which is independent of the theorems proved from it. The work is therefore self-contained against external benchmarks and receives the default non-circularity finding.
Axiom & Free-Parameter Ledger
Lean theorems connected to this paper
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IndisputableMonolith/Cost/FunctionalEquation.leanwashburn_uniqueness_aczel unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
Definition 4.11: f is T-regular if fJ is J-monogenic (∂J fJ ≡0) for every J in the T-torus; integral formulas via Em kernel on each slice (Prop 4.21)
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IndisputableMonolith/Foundation/AlexanderDuality.leanalexander_duality_circle_linking unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
T-fan construction (Def 4.3) and hypercomplex bases BJ yielding distinct monogenic operators ∂BJ that coincide only when slices coincide (eq 8)
What do these tags mean?
- matches
- The paper's claim is directly supported by a theorem in the formal canon.
- supports
- The theorem supports part of the paper's argument, but the paper may add assumptions or extra steps.
- extends
- The paper goes beyond the formal theorem; the theorem is a base layer rather than the whole result.
- uses
- The paper appears to rely on the theorem as machinery.
- contradicts
- The paper's claim conflicts with a theorem or certificate in the canon.
- unclear
- Pith found a possible connection, but the passage is too broad, indirect, or ambiguous to say the theorem truly supports the claim.
Forward citations
Cited by 4 Pith papers
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Monogenic functions over real alternative *-algebras: fundamental results and applications
Presents integral formulas and series expansions for monogenic functions in real alternative *-algebras that unify several hypercomplex analysis theories.
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Monogenic functions over real alternative *-algebras: the several hypercomplex variables case
Introduces monogenic functions of several hypercomplex variables over real alternative *-algebras and establishes Bochner-Martinelli formula, Plemelj-Sokhotski formula, and Hartogs extension theorem.
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Monogenic functions over real alternative *-algebras: the several hypercomplex variables case
Initiates monogenic functions of several hypercomplex variables over real alternative *-algebras and establishes Bochner-Martinelli, Plemelj-Sokhotski, and Hartogs extension results in this unified setting.
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Generalized partial-slice monogenic functions: the octonionic case
Generalized partial-slice monogenic functions are introduced over octonions, unifying regular and slice regular functions with proofs of identity theorem, representation formula, Cauchy integral formula, maximum modul...
Reference graph
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