Denef-Loeser zeta functions of suspensions and L\^e-Yomdin singularities
Pith reviewed 2026-05-08 01:48 UTC · model grok-4.3
The pith
New formulas for zeta functions of suspensions prove the holomorphy conjecture for plane curve singularities and the holomorphy and monodromy conjectures for Lê-Yomdin surface singularities.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The authors provide new formulas for the motivic and topological zeta functions of suspensions of hypersurfaces by an arbitrary number of points; these formulas are more general than Thom-Sebastiani type and apply for arbitrary values of the twisting parameter. The formulas involve the appearance of values of the Jordan totient function as coefficients in the zeta functions of certain auxiliary hypersurfaces of smaller dimension. With these expressions the paper proves the holomorphy conjecture for suspensions of plane curve singularities and proves both the holomorphy and monodromy conjectures for Lê-Yomdin singularities of surfaces.
What carries the argument
General formulas for the motivic and topological zeta functions of suspensions by an arbitrary number of points, which incorporate coefficients from the Jordan totient function evaluated on auxiliary lower-dimensional hypersurfaces.
If this is right
- The zeta functions of these singularities reduce explicitly to data from lower-dimensional auxiliary hypersurfaces.
- The poles of the zeta functions are located exactly where the geometry of the singularity predicts.
- The holomorphy conjecture is settled for all suspensions of plane curve singularities.
- Both the holomorphy and monodromy conjectures are settled for all Lê-Yomdin singularities of surfaces.
Where Pith is reading between the lines
- The same reduction technique might extend to prove analogous conjectures for higher-dimensional Lê-Yomdin singularities.
- Explicit computation of the Jordan totient coefficients for low-dimensional examples could produce new numerical checks of the formulas.
- The approach may connect to other invariants such as the spectrum or the Milnor fiber cohomology.
Load-bearing premise
The new general formulas for zeta functions of suspensions by an arbitrary number of points hold for the stated family of hypersurfaces and correctly capture the twisting parameter for all values.
What would settle it
A concrete suspension of a plane curve singularity for which a pole of the zeta function violates the holomorphy conjecture, or an explicit hypersurface where the derived zeta-function formula fails to match direct computation, would disprove the central claim.
Figures
read the original abstract
The holomorphy conjecture for suspensions of plane curve singularities and the holomorphy and monodromy conjectures for L\^e-Yomdin singularities of surfaces are proved. The first part of this paper provides formul{\ae} for the motivic and topological zeta functions for a family of hypersurfaces, including the suspensions by an arbitrary number of points and which are more general than Thom-Sebastiani type. These formulae generalize and are inspired by the description of the topological and the 2-twisted topological zeta functions of suspensions by 2 points of hypersurfaces, due to the first named author, Cassou-Nogu\`es, Luengo and Melle. The new general formul{\ae} deal with arbitrary values of the twisting parameter. An interesting feature of these general formul{\ae} is the appearance of values of the Jordan's totient function as coefficients of the topological and the twisted topological zeta functions of some auxiliary hypersurfaces of smaller dimension.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper derives new formulas for the motivic and topological Denef-Loeser zeta functions of a family of hypersurfaces that includes suspensions by an arbitrary number of points and is strictly larger than Thom-Sebastiani suspensions. These formulas generalize the 2-point results of Cassou-Noguès–Luengo–Melle to arbitrary twisting parameters and feature coefficients given by values of the Jordan totient function applied to auxiliary lower-dimensional zeta functions. The formulas are then substituted into generating functions to prove the holomorphy conjecture for suspensions of plane curve singularities and both the holomorphy and monodromy conjectures for Lê-Yomdin singularities of surfaces.
Significance. If the general zeta-function formulas hold, the work resolves longstanding conjectures on the location of poles of zeta functions and their compatibility with monodromy eigenvalues for these classes of singularities. The explicit appearance of Jordan totient values as coefficients and the extension to arbitrary suspension points constitute a technical contribution to the computation of motivic invariants beyond the classical Thom-Sebastiani setting.
major comments (2)
- [First part (general formulas for motivic and topological zeta functions)] The proofs of both the holomorphy conjecture (for suspensions of plane curves) and the holomorphy/monodromy conjectures (for Lê-Yomdin surfaces) rest entirely on substituting the new general zeta formulas into the relevant generating functions. The manuscript presents these formulas as an extension of the 2-point case, but supplies no independent verification—such as an explicit Denef–Loeser computation or computer-assisted check for a concrete 3-point suspension example—that the twisting-parameter dependence and the family of admissible hypersurfaces are correctly captured for n > 2.
- [Derivation of the general formulas and the substitution into the conjectures] The claim that the new formulas hold for a family strictly larger than Thom-Sebastiani suspensions and for every value of the twisting parameter is load-bearing; if the extension introduces hidden restrictions or fails to preserve the correct twisting dependence, the substitution step does not establish the conjectures. No direct comparison with known 2-point formulas is given to confirm reduction.
minor comments (1)
- [Section introducing the general zeta formulas] Notation for the twisting parameter and the auxiliary hypersurfaces should be introduced with explicit definitions before their first use in the formulas.
Simulated Author's Rebuttal
We thank the referee for the careful reading of the manuscript and the constructive comments. We respond point by point to the major remarks below.
read point-by-point responses
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Referee: [First part (general formulas for motivic and topological zeta functions)] The proofs of both the holomorphy conjecture (for suspensions of plane curves) and the holomorphy/monodromy conjectures (for Lê-Yomdin surfaces) rest entirely on substituting the new general zeta formulas into the relevant generating functions. The manuscript presents these formulas as an extension of the 2-point case, but supplies no independent verification—such as an explicit Denef–Loeser computation or computer-assisted check for a concrete 3-point suspension example—that the twisting-parameter dependence and the family of admissible hypersurfaces are correctly captured for n > 2.
Authors: The general formulas are obtained in Section 2 by a direct computation of the motivic measure on the arc space, following the same strategy as the 2-point case but without any inductive step or restriction that would invalidate the argument for n > 2. The twisting parameter enters the exponent of the integral in a uniform way that is independent of the number of suspension points. Nevertheless, we agree that an explicit low-dimensional check would improve the exposition. In the revised version we will insert, after the statement of the main formula, a short explicit computation for the 3-point suspension of the plane curve singularity defined by x² + y³ = 0, comparing the output of the new formula with the value obtained from the original Denef–Loeser definition via a direct resolution. revision: yes
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Referee: [Derivation of the general formulas and the substitution into the conjectures] The claim that the new formulas hold for a family strictly larger than Thom-Sebastiani suspensions and for every value of the twisting parameter is load-bearing; if the extension introduces hidden restrictions or fails to preserve the correct twisting dependence, the substitution step does not establish the conjectures. No direct comparison with known 2-point formulas is given to confirm reduction.
Authors: The construction in the paper allows hypersurfaces whose equation is not a sum of two functions in disjoint variables, hence strictly larger than the Thom–Sebastiani class; the motivic integral is performed on the full arc space without assuming such a decomposition. The twisting parameter appears explicitly in the definition of the zeta function and is carried through the computation without additional constraints. While the text asserts that the formulas recover the 2-point results of Cassou-Noguès–Luengo–Melle, we acknowledge that a side-by-side reduction is not displayed. We will add a dedicated remark (new Remark 2.6) that sets the number of points to 2 and the twisting parameter to 2, substitutes the Jordan totient values, and verifies term-by-term agreement with the earlier formulas. revision: partial
Circularity Check
New generalized zeta formulas derived for arbitrary suspensions and used to prove conjectures without reduction to prior inputs
full rationale
The paper states that it provides new formulas for motivic and topological zeta functions of a family of hypersurfaces that includes suspensions by an arbitrary number of points and is more general than Thom-Sebastiani type. These formulas are described as generalizing the 2-point case from prior work by the first author and collaborators, with the new versions handling arbitrary twisting parameters and featuring Jordan totient coefficients. The holomorphy and monodromy conjectures are then proved by substituting these formulas into the relevant generating functions. No equation or step in the provided description reduces the new formulas tautologically to the 2-point inputs by definition, fitting, or self-citation chain; the extension to arbitrary points and twisting introduces independent content. The derivation chain is therefore self-contained.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
-
[1]
A’Campo,La fonction zˆ eta d’une monodromie, Comment
N. A’Campo,La fonction zˆ eta d’une monodromie, Comment. Math. Helv.50(1975), 233–248
work page 1975
-
[2]
Artal,Forme de Jordan de la monodromie des singularit´ es superisol´ ees de surfaces, Mem
E. Artal,Forme de Jordan de la monodromie des singularit´ es superisol´ ees de surfaces, Mem. Amer. Math. Soc.109(1994), no. 525, x+84
work page 1994
-
[3]
Cisneros-Molina, Lˆ e D.T., and J
,Superisolated singularities and friends, Handbook of Geometry and Topology of Singularities VIII (J.L. Cisneros-Molina, Lˆ e D.T., and J. Seade, eds.), Springer Nature Switzerland, Cham, 2026, pp. 145–188
work page 2026
- [4]
-
[5]
,Monodromy conjecture for some surface singularities, Ann. Sci. ´Ecole Norm. Sup. (4)35(2002), no. 4, 605–640
work page 2002
-
[6]
,Quasi-ordinary power series and their zeta functions, Mem. Amer. Math. Soc.178(2005), no. 841, vi+85
work page 2005
-
[7]
E. Artal, J.I. Cogolludo, and J. Mart´ ın-Morales,Cremona transformations of weighted projective planes, Zariski pairs, and rational cuspidal curves, Singularities and Their Interaction with Geometry and Low Dimensional Topology (J. Fern´ andez de Bobadilla, T. Laszlo, and A. Stipsicz, eds.), Trends in Mathematics, Birkh¨ auser, Basel, 2020
work page 2020
- [8]
-
[9]
E. Brieskorn and H. Kn¨ orrer,Plane algebraic curves, Modern Birkh¨ auser Classics, Birkh¨ auser/Springer Basel AG, Basel, 1986, Translated from the German original by J. Stillwell, [2012] reprint of the 1986 edition
work page 1986
-
[10]
E. Bultot and J. Nicaise,Computing motivic zeta functions on log smooth models, Math. Z.295(2020), no. 1-2, 427–462
work page 2020
-
[11]
W. Castryck, D. Ibadula, and A. Lemahieu,The holomorphy conjecture for nondegenerate surface singular- ities, Nagoya Math. J.227(2017), 160–188
work page 2017
-
[12]
Denef,Report on Igusa’s local zeta function, Ast´ erisque (1991), no
J. Denef,Report on Igusa’s local zeta function, Ast´ erisque (1991), no. 201–203, Exp. No. 741, 359–386, S´ eminaire Bourbaki, Vol. 1990/91
work page 1991
-
[13]
,Degree of local zeta functions and monodromy, Compositio Math.89(1993), no. 2, 207–216
work page 1993
-
[14]
J. Denef and K. Hoornaert,Newton polyhedra and Igusa’s local zeta function, J. Number Theory89(2001), no. 1, 31–64
work page 2001
-
[15]
J. Denef and F. Loeser,Caract´ eristiques d’Euler-Poincar´ e, fonctions zˆ eta locales et modifications analytiques, J. Amer. Math. Soc.5(1992), no. 4, 705–720
work page 1992
-
[16]
,Motivic Igusa zeta functions, J. Algebraic Geom.7(1998), no. 3, 505–537
work page 1998
-
[17]
,Germs of arcs on singular algebraic varieties and motivic integration, Invent. Math.135(1999), no. 1, 201–232
work page 1999
-
[18]
,Motivic exponential integrals and a motivic Thom-Sebastiani theorem, Duke Math. J.99(1999), no. 2, 285–309
work page 1999
-
[19]
,Geometry on arc spaces of algebraic varieties, European Congress of Mathematics, Vol. I (Barcelona, 2000), Progr. Math., vol. 201, Birkh¨ auser, Basel, 2001, pp. 327–348
work page 2000
-
[20]
J. Denef and W. Veys,On the holomorphy conjecture for Igusa’s local zeta function, Proc. Amer. Math. Soc.123(1995), no. 10, 2981–2988
work page 1995
-
[21]
D. Eisenbud and W. Neumann,Three-dimensional link theory and invariants of plane curve singularities, Ann. Math. Stud., vol. 110, Princeton University Press, Princeton, NJ, 1985
work page 1985
-
[22]
J. Fern´ andez de Bobadilla, I. Luengo, A. Melle, and A. N´ emethi,On rational cuspidal projective plane curves, Proc. London Math. Soc. (3)92(2006), no. 1, 99–138
work page 2006
-
[23]
de Fernex,Three-dimensional counter-examples to the Nash problem, Compos
T. de Fernex,Three-dimensional counter-examples to the Nash problem, Compos. Math.149(2013), no. 9, 1519–1534
work page 2013
-
[24]
P.D. Gonz´ alez P´ erez and M. Gonz´ alez Villa,Motivic Milnor fiber of a quasi-ordinary hypersurface, J. Reine Angew. Math.687(2014), 159–205. DENEF-LOESER ZETA FUNCTIONS OF SUSPENSIONS AND L ˆE-YOMDIN 63
work page 2014
-
[25]
P. Griffiths and J. Harris,Principles of algebraic geometry, Pure and Applied Mathematics, Wiley- Interscience [John Wiley & Sons], New York, 1978
work page 1978
-
[26]
Guibert,Espaces d’arcs et invariants d’Alexander, Comment
G. Guibert,Espaces d’arcs et invariants d’Alexander, Comment. Math. Helv.77(2002), no. 4, 783–820
work page 2002
-
[27]
S.M. Gusein-Zade, I. Luengo, and A. Melle,Partial resolutions and the zeta-function of a singularity, Comment. Math. Helv.72(1997), no. 2, 244–256
work page 1997
-
[28]
Igusa,b-functions andp-adic integrals, Algebraic analysis, Vol
J.-i. Igusa,b-functions andp-adic integrals, Algebraic analysis, Vol. I, Academic Press, Boston, MA, 1988, pp. 231–241
work page 1988
-
[29]
A.J. de Jong and J.H.M. Steenbrink,Proof of a conjecture of W. Veys, Indag. Math. (N.S.)6(1995), no. 1, 99–104
work page 1995
-
[30]
T. de Jong and G. Pfister,Local analytic geometry, Advanced Lectures in Mathematics, Friedr. Vieweg & Sohn, Braunschweig, 2000, Basic theory and applications
work page 2000
-
[31]
Kashiwara,Fonctions rationnelles de type(0,1)sur le plan projectif complexe, Osaka J
H. Kashiwara,Fonctions rationnelles de type(0,1)sur le plan projectif complexe, Osaka J. Math.24(1987), no. 3, 521–577
work page 1987
-
[32]
Kizuka,Rational functions ofC ∗-type on the two-dimensional complex projective space, Tohoku Math
T. Kizuka,Rational functions ofC ∗-type on the two-dimensional complex projective space, Tohoku Math. J. (2)38(1986), no. 1, 123–178
work page 1986
-
[33]
Lˆ e D.T.,Ensembles analytiques complexes avec lieu singulier de dimension un (d’apr` es I. N. Iomdine), Seminar on Singularities (Paris, 1976/1977), Publ. Math. Univ. Paris VII, vol. 7, Univ. Paris VII, Paris, 1980, pp. 87–95
work page 1976
-
[34]
A. Lemahieu and L. Van Proeyen,Monodromy conjecture for nondegenerate surface singularities, Trans. Amer. Math. Soc.363(2011), no. 9, 4801–4829
work page 2011
-
[35]
E. Le´ on-Cardenal, J. Mart´ ın-Morales, W. Veys, and J. Viu-Sos,Motivic zeta functions onQ-Gorenstein varieties, Adv. Math.370(2020), 107192, 34
work page 2020
-
[36]
Luengo,Theµ-constant stratum is not smooth, Invent
I. Luengo,Theµ-constant stratum is not smooth, Invent. Math.90(1987), no. 1, 139–152
work page 1987
-
[37]
Mart´ ın-Morales,EmbeddedQ-resolutions for Yomdin-Lˆ e surface singularities, Israel J
J. Mart´ ın-Morales,EmbeddedQ-resolutions for Yomdin-Lˆ e surface singularities, Israel J. Math.204(2014), no. 1, 97–143
work page 2014
-
[38]
J. Nicaise,An introduction top-adic and motivic zeta functions and the monodromy conjecture, Algebraic and analytic aspects of zeta functions andL-functions, MSJ Mem., vol. 21, Math. Soc. Japan, Tokyo, 2010, pp. 141–166
work page 2010
-
[39]
M. Sebastiani and R. Thom,Un r´ esultat sur la monodromie, Invent. Math.13(1971), 90–96
work page 1971
-
[40]
N.J.A. Sloane,Jordan functionJ 2(n)(a generalization ofϕ(n)),https://oeis.org/A007434, 2024, The on-line Encyclopedia of Integer Sequences
work page 2024
-
[41]
Stanley,Enumerative combinatorics
R.P. Stanley,Enumerative combinatorics. Volume 1, second ed., Cambridge Studies in Advanced Mathe- matics, vol. 49, Cambridge University Press, Cambridge, 2012
work page 2012
-
[42]
J. S´ andor and B. Crstici,Handbook of number theory. II, Kluwer Academic Publishers, Dordrecht, 2004
work page 2004
-
[43]
Veys,Holomorphy of local zeta functions for curves, Math
W. Veys,Holomorphy of local zeta functions for curves, Math. Ann.295(1993), no. 4, 635–641
work page 1993
-
[44]
,Poles of Igusa’s local zeta function and monodromy, Bull. Soc. Math. France121(1993), no. 4, 545–598
work page 1993
-
[45]
,Determination of the poles of the topological zeta function for curves, Manuscripta Math.87(1995), no. 4, 435–448
work page 1995
-
[46]
,Zeta functions for curves and log canonical models, Proc. London Math. Soc. (3)74(1997), no. 2, 360–378
work page 1997
-
[47]
,Structure of rational open surfaces with non-positive Euler characteristic, Math. Ann.312(1998), no. 3, 527–548
work page 1998
-
[48]
,The topological zeta function associated to a function on a normal surface germ, Topology38 (1999), no. 2, 439–456
work page 1999
-
[49]
,Arc spaces, motivic integration and stringy invariants, Singularity theory and its applications, Adv. Stud. Pure Math., vol. 43, Math. Soc. Japan, Tokyo, 2006, pp. 529–572
work page 2006
-
[50]
,Introduction to the monodromy conjecture, Handbook of geometry and topology of singularities VII, Springer, Cham, 2025, pp. 721–765
work page 2025
-
[51]
J. Viu-Sos,ASagemathclass for computing (local) Igusa and topological zeta functions for Newton-non- degenerated polynomials, https://github.com/jviusos/ZetaFunctionsNewtonND-Sagemath, 2024. 64 E. ARTAL, P. GONZ ´ALEZ P ´EREZ, M. GONZ ´ALEZ VILLA, AND E. LE ´ON CARDENAL
work page 2024
-
[52]
Wall,Singular points of plane curves, London Mathematical Society Student Texts, vol
C.T.C. Wall,Singular points of plane curves, London Mathematical Society Student Texts, vol. 63, Cam- bridge University Press, Cambridge, 2004
work page 2004
-
[53]
Yomdin,Complex surfaces with a one-dimensional set of singularities, Sibirsk
Y. Yomdin,Complex surfaces with a one-dimensional set of singularities, Sibirsk. Mat. ˇZ.15(1974), 1061– 1082, 1181. Departamento de Matem ´aticas, IUMA, Universidad de Zaragoza, C. Pedro Cerbuna 12, 50009, Zaragoza, Spain. Email address:artal@unizar.es, m.gonzalez@unizar.es, eleon@unizar.es Instituto de Matem´atica Interdisciplinar, Departamento de´Algeb...
work page 1974
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