Howe duality over finite fields II: Explicit stable computation
Pith reviewed 2026-05-19 08:22 UTC · model grok-4.3
The pith
The eta and zeta correspondences of type I Howe duality over finite fields are explicitly described using the parametrization of irreducible characters of finite groups of Lie type in the stable ranges.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
In the two stable ranges, the eta and zeta correspondences are explicitly described using the parametrization of irreducible characters of finite groups of Lie type. This pins down which pairs of representations participate in the stable eta and zeta correspondences among those already known to appear with positive multiplicity in the type I Howe duality by earlier results.
What carries the argument
The translation of the eta and zeta correspondences into the parametrization of irreducible characters of finite groups of Lie type.
If this is right
- The pairs of representations in the stable Howe duality can now be listed by their character parameters rather than abstractly.
- The explicit form confirms the identification of the correspondences within the ranges where non-zero multiplicities are established by earlier work.
- Further computations of the duality can reference the standard character tables and parametrizations for these groups.
Where Pith is reading between the lines
- This explicit description provides a basis for attempting similar translations in non-stable ranges where the multiplicity behavior is less understood.
- Examining the specific mappings between parameters may uncover combinatorial rules governing the duality.
Load-bearing premise
The constructions of the eta and zeta correspondences from the first paper remain valid and translate directly into the parametrization of irreducible characters in the stable ranges without further modification.
What would settle it
Observe a specific pair of irreducible representations in a stable range whose Howe duality multiplicity is positive yet whose parameters in the character parametrization do not satisfy the explicit eta or zeta relation as described.
read the original abstract
In this second paper of a series dedicated to type I Howe duality for finite fields, we explicitly describe the eta and zeta correspondences constructed in the first paper in terms of G. Lusztig's parametrization of the irreducible characters of finite groups of Lie type in the two so-called stable ranges. This identifies the stable eta and zeta correspondences among the pairs of irreducible representations whose occurence with non-zero multiplicity in the type I Howe duality correspondence was proved by S.-Y. Pan.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper explicitly describes the eta and zeta correspondences constructed in the first paper of the series in terms of G. Lusztig's parametrization of irreducible characters of finite groups of Lie type, restricted to the two stable ranges. It identifies these stable correspondences with the pairs of irreducible representations that occur with non-zero multiplicity in the type I Howe duality, as previously shown by S.-Y. Pan.
Significance. If the identification is correct, the result supplies an explicit, computable form for the stable part of the Howe correspondence over finite fields by leveraging the standard Lusztig parametrization. This advances the program of the series by converting the abstract correspondences of part I into concrete pairs of parameters, building directly on Pan's multiplicity theorem without introducing new free parameters or ad-hoc constructions.
minor comments (3)
- The introduction would benefit from a short paragraph recalling the precise definitions of the eta and zeta correspondences from part I, to make the translation self-contained for readers who have not recently consulted the first paper.
- In the statement of the main identification (likely Theorem 3.1 or 4.1), the precise mapping between Lusztig parameters and the stable-range representations could be written out as an explicit bijection rather than described narratively.
- A brief remark on the range of finite fields for which the stable-range hypothesis holds would clarify the scope, even if it follows from prior results.
Simulated Author's Rebuttal
We thank the referee for the positive assessment of our manuscript and for recommending minor revision. The referee's summary accurately captures the main contribution of the paper.
read point-by-point responses
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Referee: The paper explicitly describes the eta and zeta correspondences constructed in the first paper of the series in terms of G. Lusztig's parametrization of irreducible characters of finite groups of Lie type, restricted to the two stable ranges. It identifies these stable correspondences with the pairs of irreducible representations that occur with non-zero multiplicity in the type I Howe duality, as previously shown by S.-Y. Pan.
Authors: We appreciate the referee's concise and accurate summary of the results. The explicit identification in the stable ranges is the central point of the paper, obtained by combining the abstract correspondences from part I with Lusztig's parametrization and Pan's multiplicity theorem. No new free parameters are introduced. revision: no
Circularity Check
No significant circularity detected
full rationale
The paper performs an explicit re-labeling of the eta and zeta correspondences (whose existence and basic properties are taken from the author's prior Part I) into the external Lusztig parametrization of irreducible characters of finite groups of Lie type, restricted to the stable ranges already known to be multiplicity-free by Pan's independent theorem. No derivation step equates a claimed prediction or first-principles result to its own inputs by construction, no fitted parameter is renamed as a prediction, and no uniqueness theorem is imported from the same authors' prior work as an external fact. The central identification therefore rests on external benchmarks (Lusztig, Pan) plus the prior construction, rendering the derivation self-contained rather than circular.
Axiom & Free-Parameter Ledger
axioms (2)
- standard math Lusztig's parametrization correctly labels all irreducible characters of the relevant finite groups of Lie type
- domain assumption The multiplicity results of S.-Y. Pan hold for the pairs under consideration
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.
We explicitly describe the eta and zeta correspondences ... in terms of G. Lusztig’s parametrization ... semisimple element s ... unipotent representation u ... central sign data ... symbols of type C ... defect a−b odd ... rank r
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IndisputableMonolith/Foundation/AlexanderDuality.leanalexander_duality_circle_linking unclear?
unclearRelation between the paper passage and the cited Recognition theorem.
symbols of rank r of type C or B ... a−b odd ... dimension formula involving q-powers and qc[a,b]
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.
Reference graph
Works this paper leans on
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work page 2016
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J. Epequin Chavez. Extremal unipotent representations for the finite Howe correspondence, J. Algebra 535 (2019), 480-502
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W.T. Gan, S. Takeda. A proof of the Howe duality conjecture. J. Amer. Math. Soc., 29 (2016), 473-493
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S. Gurevich, R. Howe. Small representations of finite classical groups, Progr. Math., 323 Birkh¨ auser/Springer, Cham, 2017, 209-234
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R. Howe. Invariant Theory and Duality for Classical Groups over Finite Fields, with Applications to their Singular Representation Theory, preprint, Yale Uni- versity
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Lusztig: Characters of Reductive Groups over a Finite Field
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S.-Y. Pan. Lusztig correspondence and Howe correspondence for finite reduc- tive dual pairs. Math. Ann. 390 (2024), 4657-4699. 59
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Z. Yun. Theta correspondence and relative Langlands. Harvard Arithmetic Quantum Field Theory Conference, March 29, 2024, https://www.youtube.com/watch?v=Bb6aTlzNDV4
work page 2024
discussion (0)
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