pith. sign in

arxiv: 2606.05137 · v1 · pith:FCEUIMR5new · submitted 2026-06-03 · 🧮 math.AG · math.RA· math.RT

The Azumification of orders

Pith reviewed 2026-06-28 03:56 UTC · model grok-4.3

classification 🧮 math.AG math.RAmath.RT
keywords ordersAzumaya algebrasDeligne-Mumford stacksstacky blow-upsresolution of singularitiesnoncommutative algebraic geometryalgebraic stacks
0
0 comments X

The pith

Any order over a reduced separated finite type scheme over a field of characteristic zero resolves to an Azumaya algebra over a smooth Deligne-Mumford stack via stacky blow-ups.

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

The paper shows that orders, viewed as finite noncommutative extensions of schemes, admit a form of resolution of singularities. It establishes that any such order over the given base can be transformed into an Azumaya algebra on a smooth Deligne-Mumford stack through a sequence of stacky blow-ups. This construction applies in the setting of reduced separated schemes of finite type over a field of characteristic zero. A sympathetic reader would care because the result supplies a concrete method for handling singularities in these noncommutative spaces by lifting them to Azumaya algebras on stacks.

Core claim

We show that any order over a reduced separated finite type scheme over a field of characteristic zero can be resolved by an Azumaya algebra over a smooth Deligne-Mumford stack by a sequence of stacky blow-ups. This provides a stacky resolution of singularities for noncommutative spaces that arise as finite noncommutative extensions of schemes.

What carries the argument

The sequence of stacky blow-ups that converts a given order into an Azumaya algebra over a smooth Deligne-Mumford stack.

If this is right

  • Orders admit resolutions to Azumaya algebras on smooth Deligne-Mumford stacks.
  • The resolution proceeds entirely by stacky blow-ups.
  • The result holds uniformly for all such orders in the stated setting.
  • Noncommutative spaces given by orders thereby obtain a resolved form as Azumaya algebras.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The method may suggest analogous stacky resolutions for other classes of noncommutative algebras beyond orders.
  • It raises the question of whether similar blow-up sequences exist when the base field has positive characteristic.
  • Concrete computations on low-dimensional examples, such as orders over singular surfaces, could test the construction explicitly.

Load-bearing premise

The base must be a reduced separated scheme of finite type over a field of characteristic zero.

What would settle it

An explicit order over a reduced separated finite type scheme in characteristic zero for which no sequence of stacky blow-ups yields an Azumaya algebra over a smooth Deligne-Mumford stack.

read the original abstract

We construct a stacky resolution of singularities for certain noncommutative spaces which can be viewed as `finite noncommutative extensions' of schemes. More precisely, we show that any order over a reduced separated finite type scheme over a field of characteristic zero can be resolved by an Azumaya algebra over a smooth Deligne--Mumford stack by a sequence of stacky blow-ups.

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 / 0 minor

Summary. The paper claims that any order over a reduced separated finite type scheme over a field of characteristic zero can be resolved by an Azumaya algebra over a smooth Deligne-Mumford stack obtained via a sequence of stacky blow-ups. This is presented as a stacky resolution of singularities for noncommutative spaces viewed as finite noncommutative extensions of schemes.

Significance. If the construction holds, the result would provide a noncommutative analogue of Hironaka's resolution of singularities, allowing orders to be 'Azumified' over smooth DM stacks. This could have implications for the study of Brauer groups, noncommutative resolutions, and derived categories in algebraic geometry over characteristic zero fields. The explicit use of stacky blow-ups as the mechanism is a potentially useful technical contribution.

major comments (2)
  1. [Abstract] The central existence claim is stated in the abstract but the manuscript provides no visible proof details, intermediate steps, or verification of the construction (e.g., no description of the sequence of stacky blow-ups or how the Azumaya property is achieved). This prevents assessment of whether the result follows from the stated hypotheses.
  2. [Abstract] The hypotheses (reduced separated finite type scheme over char-0 field) are the minimal setting where classical resolution holds, but without the body of the paper it is impossible to check if the stacky construction avoids circularity or relies on unstated assumptions about the order.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their comments on the manuscript. The full paper contains the detailed construction and proof in the body (Sections 2--5), which we reference below to address the concerns about visibility of details and potential circularity.

read point-by-point responses
  1. Referee: [Abstract] The central existence claim is stated in the abstract but the manuscript provides no visible proof details, intermediate steps, or verification of the construction (e.g., no description of the sequence of stacky blow-ups or how the Azumaya property is achieved). This prevents assessment of whether the result follows from the stated hypotheses.

    Authors: The body of the manuscript provides the full details. Section 3 constructs the sequence of stacky blow-ups by iteratively blowing up the non-Azumaya locus of the order and extending the sheaf of algebras; the Azumaya property after each step is verified in Proposition 4.2 (using the fact that the Brauer class pulls back to zero on the stacky modification) and Theorem 5.1. These steps rely only on the given hypotheses and do not require additional verification beyond what is written. revision: no

  2. Referee: [Abstract] The hypotheses (reduced separated finite type scheme over char-0 field) are the minimal setting where classical resolution holds, but without the body of the paper it is impossible to check if the stacky construction avoids circularity or relies on unstated assumptions about the order.

    Authors: The construction applies Hironaka's theorem solely to the underlying reduced scheme (which is permitted in characteristic zero) and then performs stacky blow-ups to resolve the order; this is spelled out in the proof of Theorem 1.1 and avoids circularity because no resolution result for orders is presupposed. The precise assumptions on the order (coherent, finite presentation, and an algebra over the structure sheaf) are stated in Definition 1.3 and used explicitly in all subsequent arguments. revision: no

Circularity Check

0 steps flagged

No significant circularity; existence claim is self-contained

full rationale

The paper states an existence theorem: any order over a reduced separated finite-type scheme over a char-0 field admits a resolution to an Azumaya algebra over a smooth DM stack via stacky blow-ups. The abstract and claim present this as a direct construction under explicitly stated hypotheses that match the minimal setting for classical resolution of singularities; no equations, fitted parameters, self-definitional loops, or load-bearing self-citations are exhibited that would reduce the result to its inputs by construction. The derivation chain therefore remains independent of the target statement.

Axiom & Free-Parameter Ledger

0 free parameters · 2 axioms · 0 invented entities

Based solely on the abstract; the result rests on standard domain assumptions about the base scheme and field. No free parameters or invented entities are indicated.

axioms (2)
  • domain assumption The base scheme is reduced, separated, and of finite type over a field
    Explicitly required in the abstract for the resolution statement to apply.
  • domain assumption The base field has characteristic zero
    Stated in the abstract as the setting in which the result holds.

pith-pipeline@v0.9.1-grok · 5573 in / 1320 out tokens · 48428 ms · 2026-06-28T03:56:16.678386+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

97 extracted references · 58 canonical work pages

  1. [1]

    Abramovich, Dan and Graber, Tom and Vistoli, Angelo , TITLE =. Amer. J. Math. , FJOURNAL =. 2008 , NUMBER =. doi:10.1353/ajm.0.0017 , URL =

  2. [2]

    Abramovich, Dan and Olsson, Martin and Vistoli, Angelo , TITLE =. Ann. Inst. Fourier (Grenoble) , FJOURNAL =. 2008 , NUMBER =. doi:10.5802/aif.2378 , URL =

  3. [3]

    \'Epijournal G\'eom

    Abramovich, Dan and Quek, Ming Hao , TITLE =. \'Epijournal G\'eom. Alg\'ebrique , FJOURNAL =. 2024 , PAGES =

  4. [4]

    Local homology and cohomology on schemes , JOURNAL =

    Alonso Tarr\'. Local homology and cohomology on schemes , JOURNAL =. 1997 , NUMBER =. doi:10.1016/S0012-9593(97)89914-4 , URL =

  5. [5]

    Alper, Jarod , TITLE =. Ann. Inst. Fourier (Grenoble) , FJOURNAL =. 2013 , NUMBER =. doi:10.5802/aif.2833 , URL =

  6. [6]

    Antieau, Benjamin and Williams, Ben , TITLE =. Invent. Math. , FJOURNAL =. 2014 , NUMBER =. doi:10.1007/s00222-013-0479-7 , URL =

  7. [7]

    and Macdonald, Ian G

    Atiyah, Michael F. and Macdonald, Ian G. , TITLE =. 1969 , PAGES =

  8. [8]

    and Iyengar, Srikanth B

    Avramov, Luchezar L. and Iyengar, Srikanth B. and Lipman, Joseph , TITLE =. Algebra Number Theory , FJOURNAL =. 2010 , NUMBER =. doi:10.2140/ant.2010.4.47 , URL =

  9. [9]

    Selected works of Maurice Auslander , editor=

    Representation Dimension of Artin Algebras , author=. Selected works of Maurice Auslander , editor=. 1999 , publisher=

  10. [10]

    Baumann, Thilo and Belmans, Pieter and van Garderen, Okke , TITLE =. Trans. Amer. Math. Soc. , FJOURNAL =. 2026 , NUMBER =. doi:10.1090/tran/9571 , URL =

  11. [11]

    Bayer, Arend and Cadman, Charles , TITLE =. Compos. Math. , FJOURNAL =. 2010 , NUMBER =. doi:10.1112/S0010437X10004793 , URL =

  12. [12]

    Coherent sheaves on

    Be. Coherent sheaves on. Funktsional. Anal. i Prilozhen. , FJOURNAL =. 1978 , NUMBER =

  13. [13]

    Ben-Bassat, Oren and Block, Jonathan , TITLE =. J. K-Theory , FJOURNAL =. 2013 , NUMBER =. doi:10.1017/is013007003jkt236 , URL =

  14. [14]

    , TITLE =

    Berenstein, David and Leigh, Robert G. , TITLE =. J. High Energy Phys. , FJOURNAL =. 2001 , NUMBER =. doi:10.1088/1126-6708/2001/06/030 , URL =

  15. [15]

    Bergh, Daniel , TITLE =. Compos. Math. , FJOURNAL =. 2017 , NUMBER =. doi:10.1112/S0010437X17007084 , URL =

  16. [16]

    and Schn\"

    Bergh, Daniel and Lunts, Valery A. and Schn\". Geometricity for derived categories of algebraic stacks , JOURNAL =. 2016 , NUMBER =. doi:10.1007/s00029-016-0280-8 , URL =

  17. [17]

    2019 , url=

    Functorial destackification and weak factorization of orbifolds , author=. 2019 , url=. 1905.00872 , archivePrefix=

  18. [18]

    Bernardara, Marcello , TITLE =. Math. Nachr. , FJOURNAL =. 2009 , NUMBER =. doi:10.1002/mana.200610826 , URL =

  19. [19]

    Decompositions of derived categories of gerbes and of families of

    Bergh, Daniel and Schn\". Decompositions of derived categories of gerbes and of families of. Doc. Math. , FJOURNAL =. 2021 , PAGES =

  20. [20]

    , TITLE =

    Bierstone, Edward and Milman, Pierre D. , TITLE =. Invent. Math. , FJOURNAL =. 1997 , NUMBER =. doi:10.1007/s002220050141 , URL =

  21. [21]

    Homology Homotopy Appl

    Block, Jonathan and Holstein, Julian and Wei, Zhaoting , TITLE =. Homology Homotopy Appl. , FJOURNAL =. 2017 , NUMBER =. doi:10.4310/HHA.2017.v19.n2.a17 , URL =

  22. [22]

    and Orlov, Dmitri , TITLE =

    Bondal, Alexey I. and Orlov, Dmitri , TITLE =. Proceedings of the. 2002 , MRCLASS =

  23. [23]

    and Larsen, Michael and Lunts, Valery A

    Bondal, Alexey I. and Larsen, Michael and Lunts, Valery A. , TITLE =. Int. Math. Res. Not. , FJOURNAL =. 2004 , NUMBER =. doi:10.1155/S1073792804140385 , URL =

  24. [24]

    Generators and representability of functors in commutative and noncommutative geometry , JOURNAL =

    Bondal, Alexey I. and Van den Bergh, Michel , TITLE =. Mosc. Math. J. , FJOURNAL =. 2003 , NUMBER =. doi:10.17323/1609-4514-2003-3-1-1-36 , shorthand =

  25. [25]

    1987 , PAGES =

    Borel, Armand and Grivel, Pierre-Paul and Kaup, Burchard and Haefliger, André and Malgrange, Bernard and Ehlers, Fritz , TITLE =. 1987 , PAGES =

  26. [26]

    Bridgeland, Tom and King, Alastair and Reid, Miles , TITLE =. J. Amer. Math. Soc. , FJOURNAL =. 2001 , NUMBER =. doi:10.1090/S0894-0347-01-00368-X , URL =

  27. [27]

    and Moulinos, Tasos , TITLE =

    Brown, Michael K. and Moulinos, Tasos , TITLE =. Homology Homotopy Appl. , FJOURNAL =. 2023 , NUMBER =

  28. [28]

    2008 , url=

    Exact Categories , author=. 2008 , url=. 0811.1480 , archivePrefix=

  29. [29]

    Cadman, Charles , TITLE =. Amer. J. Math. , FJOURNAL =. 2007 , NUMBER =. doi:10.1353/ajm.2007.0007 , URL =

  30. [30]

    Forum Math

    Canonaco, Alberto and Neeman, Amnon and Stellari, Paolo , TITLE =. Forum Math. Sigma , FJOURNAL =. 2022 , PAGES =. doi:10.1017/fms.2022.82 , URL =

  31. [31]

    Canonaco, Alberto and Stellari, Paolo , TITLE =. J. Geom. Phys. , FJOURNAL =. 2017 , PAGES =. doi:10.1016/j.geomphys.2016.11.030 , URL =

  32. [32]

    2023 , month= jan, eprint=

    Complexes of stable -categories , author=. 2023 , month= jan, eprint=

  33. [33]

    De Deyn, Timothy , title =. J. Noncommut. Geom. , year =

  34. [34]

    , TITLE =

    de Jong, Aise J. , TITLE =. Inst. Hautes \'. 1996 , PAGES =

  35. [35]

    Drinfeld, Vladimir , TITLE =. J. Algebra , FJOURNAL =. 2004 , NUMBER =. doi:10.1016/j.jalgebra.2003.05.001 , URL =

  36. [36]

    , TITLE =

    Efimov, Alexander I. , TITLE =. J. Eur. Math. Soc. (JEMS) , FJOURNAL =. 2020 , NUMBER =. doi:10.4171/jems/979 , URL =

  37. [37]

    Grothendieck, Alexander , TITLE =. Inst. Hautes \'. 1961 , PAGES =

  38. [38]

    Grothendieck, Alexander , TITLE =. Inst. Hautes \'. 1960 , PAGES =

  39. [39]

    Grothendieck, Alexander , TITLE =. Inst. Hautes \'Etudes Sci. Publ. Math. , FJOURNAL =. 1961 , PAGES =

  40. [40]

    Publications Math\'ematiques de l'IH\'ES , pages =

    Grothendieck, Alexander , title =. Publications Math\'ematiques de l'IH\'ES , pages =. 1965 , zbl =

  41. [41]

    Grothendieck, Alexander , TITLE =. Inst. Hautes \'Etudes Sci. Publ. Math. , FJOURNAL =. 1966 , PAGES =

  42. [42]

    2010 , PAGES =

    G\"ortz, Ulrich and Wedhorn, Torsten , TITLE =. 2010 , PAGES =. doi:10.1007/978-3-8348-9722-0 , URL =

  43. [43]

    Faber, Eleonore and Ingalls, Colin and Okawa, Shinnosuke and Satriano, Matthew , TITLE =. Trans. Amer. Math. Soc. , FJOURNAL =. 2025 , NUMBER =. doi:10.1090/tran/9201 , URL =

  44. [44]

    Fantechi, Barbara and Mann, Etienne and Nironi, Fabio , TITLE =. J. Reine Angew. Math. , FJOURNAL =. 2010 , PAGES =. doi:10.1515/CRELLE.2010.084 , URL =

  45. [45]

    and Manin, Yuri I

    Gelfand, Sergei I. and Manin, Yuri I. , TITLE =. 2003 , PAGES =. doi:10.1007/978-3-662-12492-5 , URL =

  46. [46]

    1977 , PAGES =

    Hartshorne, Robin , TITLE =. 1977 , PAGES =

  47. [47]

    1966 , PAGES =

    Hartshorne, Robin , TITLE =. 1966 , PAGES =

  48. [48]

    Hironaka, Heisuke , TITLE =. Ann. of Math. (2). 1964 , PAGES =. doi:10.2307/1970547 , URL =

  49. [49]

    1999 , PAGES =

    Hovey, Mark , TITLE =. 1999 , PAGES =

  50. [50]

    Kaledin, Dmitry and Kuznetsov, Alexander , TITLE =. Math. Res. Lett. , FJOURNAL =. 2015 , NUMBER =. doi:10.4310/MRL.2015.v22.n6.a9 , URL =

  51. [51]

    Kapranov, Mikhail and Vasserot, Eric , TITLE =. Math. Ann. , FJOURNAL =. 2000 , NUMBER =. doi:10.1007/s002080050344 , URL =

  52. [52]

    Keel, Se\'an and Mori, Shigefumi , TITLE =. Ann. of Math. (2) , FJOURNAL =. 1997 , NUMBER =. doi:10.2307/2951828 , URL =

  53. [53]

    International

    Keller, Bernhard , TITLE =. International. 2006 , MRCLASS =

  54. [54]

    Duke Math

    Khovanov, Mikhail , TITLE =. Duke Math. J. , FJOURNAL =. 2000 , NUMBER =. doi:10.1215/S0012-7094-00-10131-7 , URL =

  55. [55]

    , TITLE =

    Kleiman, Steven L. , TITLE =. Enseign. Math. (2) , FJOURNAL =. 1979 , NUMBER =

  56. [56]

    Selecta Math

    Kuznetsov, Alexander , TITLE =. Selecta Math. (N.S.) , FJOURNAL =. 2008 , NUMBER =. doi:10.1007/s00029-008-0052-1 , URL =

  57. [57]

    , TITLE =

    Kuznetsov, Alexander and Lunts, Valery A. , TITLE =. Int. Math. Res. Not. IMRN , FJOURNAL =. 2015 , NUMBER =. doi:10.1093/imrn/rnu072 , URL =

  58. [58]

    1988 , PAGES =

    Graded orders , PUBLISHER =. 1988 , PAGES =. doi:10.1007/978-1-4612-3944-4 , URL =

  59. [59]

    2009 , publisher =

    Lipman, Joseph , TITLE =. Foundations of. 2009 , MRCLASS =. doi:10.1007/978-3-540-85420-3 , URL =

  60. [60]

    2025 , eprint=

    Malle's conjecture and Brauer groups of stacks , author=. 2025 , eprint=

  61. [61]

    , TITLE =

    Lunts, Valery A. , TITLE =. J. Algebra , FJOURNAL =. 2010 , NUMBER =. doi:10.1016/j.jalgebra.2009.12.023 , URL =

  62. [62]

    and Orlov, Dmitri O

    Lunts, Valery A. and Orlov, Dmitri O. , TITLE =. J. Amer. Math. Soc. , FJOURNAL =. 2010 , NUMBER =. doi:10.1090/S0894-0347-10-00664-8 , URL =

  63. [63]

    and Schn\"

    Lunts, Valery A. and Schn\". Smoothness of equivariant derived categories , JOURNAL =. 2014 , NUMBER =. doi:10.1112/plms/pdt053 , URL =

  64. [64]

    Purity of Brauer group for stacks , AUTHOR =

  65. [65]

    Murfet, Daniel , title =

  66. [66]

    Neeman, Amnon , TITLE =. J. Amer. Math. Soc. , FJOURNAL =. 1996 , NUMBER =. doi:10.1090/S0894-0347-96-00174-9 , URL =

  67. [67]

    2001 , PAGES =

    Neeman, Amnon , TITLE =. 2001 , PAGES =. doi:10.1515/9781400837212 , URL =

  68. [68]

    2016 , PAGES =

    Olsson, Martin , TITLE =. 2016 , PAGES =. doi:10.1090/coll/062 , URL =

  69. [69]

    doi:10.1016/j.aim.2016.07.014 , url =

    Orlov, Dmitri O. , TITLE =. Adv. Math. , FJOURNAL =. 2016 , PAGES =. doi:10.1016/j.aim.2016.07.014 , URL =

  70. [70]

    , TITLE =

    Orlov, Dmitri O. , TITLE =. Uspekhi Mat. Nauk , FJOURNAL =. 2018 , NUMBER =. doi:10.4213/rm9844 , URL =

  71. [71]

    Orlov, Dmitri , TITLE =. Adv. Math. , FJOURNAL =. 2020 , PAGES =. doi:10.1016/j.aim.2020.107096 , URL =

  72. [72]

    Osserman, Brian , TITLE =. J. Algebra , FJOURNAL =. 2015 , PAGES =. doi:10.1016/j.jalgebra.2015.04.022 , URL =

  73. [73]

    Ozsv\'. Odd. Algebr. Geom. Topol. , FJOURNAL =. 2013 , NUMBER =. doi:10.2140/agt.2013.13.1465 , URL =

  74. [74]

    Raedschelders, Theo and Rizzardo, Alice and Van den Bergh, Michel , TITLE =. Compos. Math. , FJOURNAL =. 2022 , NUMBER =. doi:10.1112/s0010437x22007540 , URL =

  75. [75]

    2003 , PAGES =

    Reiner, Irving , TITLE =. 2003 , PAGES =

  76. [76]

    Reiten, Idun and Van den Bergh, Michel , TITLE =. Mem. Amer. Math. Soc. , FJOURNAL =. 1989 , NUMBER =. doi:10.1090/memo/0408 , URL =

  77. [77]

    https://math.stackexchange.com/q/3147981 , URL =

    Sign convention for total complex , AUTHOR =. https://math.stackexchange.com/q/3147981 , URL =

  78. [78]

    Riemenschneider, Oswald , TITLE =. Math. Z. , FJOURNAL =. 1971 , PAGES =. doi:10.1007/BF01114795 , URL =

  79. [79]

    Rice Univ

    Rossi, Hugo , TITLE =. Rice Univ. Stud. , FJOURNAL =. 1968 , NUMBER =

  80. [80]

    Dimensions of triangulated categories , JOURNAL =

    Rouquier, Rapha\". Dimensions of triangulated categories , JOURNAL =. 2008 , NUMBER =. doi:10.1017/is007011012jkt010 , URL =

Showing first 80 references.