via @EmailGateBot
[News GDR EFI] 28 et 29 mai à Rennes: Feuilletages et géométrie complexe
Cher(e)s collègues, À la suite de la conférence à l'IMPA (Rio De Janeiro) ce mois de novembre 2025, se tiendra à Rennes fin mai 2026 une déclinaison plus locale pour célébrer l'activité scientifique de Frank Loray à l'occasion de ses 60 ans. Le programme prévisionnel ainsi que le formulaire d'inscription (obligatoire) se trouve à l'adresse:https://loray60.sciencesconf.org/ Nous espérons vous y retrouver nombreux pour rendre hommage à notre collègue et ami ! Bien à vous tou(te)s,Le comité d'organisation.Guy CasaleViktoria HeuLoïc Teyssier
Cher(e)s collègues,
À la suite de la conférence à l'IMPA (Rio De Janeiro) ce mois de novembre 2025, se tiendra à Rennes fin mai 2026 une déclinaison plus locale pour célébrer l'activité scientifique de Frank Loray à l'occasion de ses 60 ans. Le programme prévisionnel ainsi que le formulaire d'inscription (obligatoire) se trouve à l'adresse:
https://loray60.sciencesconf.org/
Nous espérons vous y retrouver nombreux pour rendre hommage à notre collègue et ami !
Bien à vous tou(te)s,
Le comité d'organisation.
Guy Casale
Viktoria Heu
Loïc Teyssier
[News GDR EFI] 28 et 29 mai à Rennes: Feuilletages et géométrie complexe
Cher(e)s collègues, À la suite de la conférence à l'IMPA (Rio De Janeiro) ce mois de novembre 2025, se tiendra à Rennes fin mai 2026 une déclinaison plus locale pour célébrer l'activité scientifique de Frank Loray à l'occasion de ses 60 ans. Le programme prévisionnel ainsi que le formulaire d'inscription (obligatoire) se trouve à l'adresse:https://loray60.sciencesconf.org/ Nous espérons vous y retrouver nombreux pour rendre hommage à notre collègue et ami ! Bien à vous tou(te)s,Le comité d'organisation.Guy CasaleViktoria HeuLoïc Teyssier
Cher(e)s collègues,
À la suite de la conférence à l'IMPA (Rio De Janeiro) ce mois de novembre 2025, se tiendra à Rennes fin mai 2026 une déclinaison plus locale pour célébrer l'activité scientifique de Frank Loray à l'occasion de ses 60 ans. Le programme prévisionnel ainsi que le formulaire d'inscription (obligatoire) se trouve à l'adresse:
https://loray60.sciencesconf.org/
Nous espérons vous y retrouver nombreux pour rendre hommage à notre collègue et ami !
Bien à vous tou(te)s,
Le comité d'organisation.
Guy Casale
Viktoria Heu
Loïc Teyssier
via @EmailGateBot
[News GDR EFI] Expose Y.Ikeda Séminaire ED motiviques l'IHP 13.02.2026
Dear All,
There will be a talk by Yasushi Ikeda (Cracow Polytechnical University) at the IHP, salle Olga Ladyjenskaia (ground floor), on Friday 13 February at 15:00 ( https://indico.math.cnrs.fr/event/16097/ )
Please find a zoom link with the credentials for the talk:
Réunion Zoom de Vladimir ROUBTSOV
Heure: 13 feb. 2026 02:45 PM Paris
https://cnrs.zoom.us/j/93271910885?pwd=xAirYP1vUWG2fCo5dJBpnaKIbvJ5eU.1
Meeting ID: 932 7191 0885
Passcode: 4q9vxi
With best regards,
`Équations différentielles motiviques et au–delà’
============
Title: Quantum Argument--Shift Subalgebras via Quantized Shift Operators
Abstract: The argument--shift method constructs maximal Poisson-commutative subalgebras of the symmetric algebra $S(\mathfrak g)$ of a Lie algebra $\mathfrak g$ with respect to the Lie--Poisson bracket. Their quantizations---known as quantum argument--shift subalgebras---form maximal commutative subalgebras of the universal enveloping algebra $U(\mathfrak g)$ and play a fundamental role in quantum integrable systems. Although existence and uniqueness of these quantizations have been established in many cases, the underlying argument--shift procedures, realized as derivations of $S(\mathfrak g)$, had not previously been quantized. Recently, Georgy Sharygin and I defined quantized argument--shift procedures for $\mathfrak_n$ and proved that they generate the associated quantum argument--shift subalgebras.
[News GDR EFI] Expose Y.Ikeda Séminaire ED motiviques l'IHP 13.02.2026
Dear All,
There will be a talk by Yasushi Ikeda (Cracow Polytechnical University) at the IHP, salle Olga Ladyjenskaia (ground floor), on Friday 13 February at 15:00 ( https://indico.math.cnrs.fr/event/16097/ )
Please find a zoom link with the credentials for the talk:
Réunion Zoom de Vladimir ROUBTSOV
Heure: 13 feb. 2026 02:45 PM Paris
https://cnrs.zoom.us/j/93271910885?pwd=xAirYP1vUWG2fCo5dJBpnaKIbvJ5eU.1
Meeting ID: 932 7191 0885
Passcode: 4q9vxi
With best regards,
`Équations différentielles motiviques et au–delà’
============
Title: Quantum Argument--Shift Subalgebras via Quantized Shift Operators
Abstract: The argument--shift method constructs maximal Poisson-commutative subalgebras of the symmetric algebra $S(\mathfrak g)$ of a Lie algebra $\mathfrak g$ with respect to the Lie--Poisson bracket. Their quantizations---known as quantum argument--shift subalgebras---form maximal commutative subalgebras of the universal enveloping algebra $U(\mathfrak g)$ and play a fundamental role in quantum integrable systems. Although existence and uniqueness of these quantizations have been established in many cases, the underlying argument--shift procedures, realized as derivations of $S(\mathfrak g)$, had not previously been quantized. Recently, Georgy Sharygin and I defined quantized argument--shift procedures for $\mathfrak_n$ and proved that they generate the associated quantum argument--shift subalgebras.
via @EmailGateBot
[News GDR EFI] Séminaire Différentiel - 14 avril 2026 - LIP6 (Jussieu)
Chères et chers collègues,
La prochaine journée du Séminaire Différentiel aura lieu le
*mardi 14 avril 2026*
au Laboratoire d’Informatique de Paris 6 (LIP6, 4 place Jussieu, Paris).
Les orateurs de la journée seront Veronica Fantini, Kilian Raschel et Sergey Yurkevich.
Vous trouverez plus d'informations sur la page du séminaire : http://divizio.joomla.com/sem-diff
N'hésitez pas à diffuser ce message.
À bientôt,
Les organisateurs,
Alin Bostan et Lucia Di Vizio
[News GDR EFI] Séminaire Différentiel - 14 avril 2026 - LIP6 (Jussieu)
Chères et chers collègues,
La prochaine journée du Séminaire Différentiel aura lieu le
*mardi 14 avril 2026*
au Laboratoire d’Informatique de Paris 6 (LIP6, 4 place Jussieu, Paris).
Les orateurs de la journée seront Veronica Fantini, Kilian Raschel et Sergey Yurkevich.
Vous trouverez plus d'informations sur la page du séminaire : http://divizio.joomla.com/sem-diff
N'hésitez pas à diffuser ce message.
À bientôt,
Les organisateurs,
Alin Bostan et Lucia Di Vizio
😇1
via @EmailGateBot
[News GDR EFI] exposé de Pierre Schapira 27.02á l'IHP
Dear All, There will be a talk by Pierre Schapira (Sorbonne Université, CNRS IMJ-PRG) at the IHP, salle M-L Dubreil Jacotin (ex salle 421), on Friday 27 February at 15:00 ( https://indico.math.cnrs.fr/event/16193/ )
Please find a zoom link with the credentials for the talk:
Sujet: Réunion Zoom de Vladimir ROUBTSOV
Heure: 27 févr. 2026 02:45 PM Paris
https://cnrs.zoom.us/j/91694011965?pwd=vdihx64UJbcmHZlRvyPp6LIPovstSP.1
ID de réunion: 916 9401 1965
Code secret: 1ZycPh
With best regards,
`Équations différentielles motiviques et au–delà’
============
Title: Sheaves for spacetimes
Abstract: Attached to the email
[News GDR EFI] exposé de Pierre Schapira 27.02á l'IHP
Dear All, There will be a talk by Pierre Schapira (Sorbonne Université, CNRS IMJ-PRG) at the IHP, salle M-L Dubreil Jacotin (ex salle 421), on Friday 27 February at 15:00 ( https://indico.math.cnrs.fr/event/16193/ )
Please find a zoom link with the credentials for the talk:
Sujet: Réunion Zoom de Vladimir ROUBTSOV
Heure: 27 févr. 2026 02:45 PM Paris
https://cnrs.zoom.us/j/91694011965?pwd=vdihx64UJbcmHZlRvyPp6LIPovstSP.1
ID de réunion: 916 9401 1965
Code secret: 1ZycPh
With best regards,
`Équations différentielles motiviques et au–delà’
============
Title: Sheaves for spacetimes
Abstract: Attached to the email
via @EmailGateBot
[News GDR EFI] Séminaire "ED motiviques etau-delà", IHP, le13 MarsExposéde D.Kubrak
Dear All,
There will be a talk by Dmitry Kubrak (CNRS, Université Paris-Saclay) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 13 March at 15:00 ( https://indico.math.cnrs.fr/event/16275/ )
Please find a Zoom link with the credentials for the talk:
Sujet: Réunion Zoom de Vladimir ROUBTSOV
Heure: 13 mars 2026 02:45 PM Paris
https://cnrs.zoom.us/j/98130850395?pwd=kfinrm6rM3hsWrzT5bL1yf1Rwhq6Is.1
ID de réunion: 981 3085 0395
Code secret: ZtqN8q
With best regards,
`Équations différentielles motiviques et au-delà’
============
Title: Сategorical quantizations of symplectic varieties in char p
Abstract: Originally motivated by physics, mathematically a quantization of a Poisson variety X is simply a formal 1-parameter deformation of its sheaf of functions that in the first approximation agrees with the Poisson bracket. In the algebraic context such quantizations tend not to exist globally due to a possible non-vanishing of cohomology of relevant coherent sheaves. It was observed by Kontsevich that in the algebraic context it might in fact be more natural to consider formal deformations of the category QCoh(X) rather than the sheaf of algebras O_X. I will talk about joint work with Bogdanova, Travkin and Vologodsky where, building on the work of Bezrukavnikov and Kaledin, we construct a canonical such categorical quantization for (restricted) symplectic varieties in char p. An interesting feature of char p is that this quantization in fact naturally extends from the formal disk to a family of categories over P^1 which carries strong resemblance with the Simpson’s twistor space picture. This allows to associate to any restricted symplectic scheme a category of "mod p F-gauges", which agrees with Bhatt-Lurie F-gauges for Y in the case X=T^*Y. If time permits I will also talk about some further results about quantizations over Z/p^n or even Z (work in progress).
[News GDR EFI] Séminaire "ED motiviques etau-delà", IHP, le13 MarsExposéde D.Kubrak
Dear All,
There will be a talk by Dmitry Kubrak (CNRS, Université Paris-Saclay) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 13 March at 15:00 ( https://indico.math.cnrs.fr/event/16275/ )
Please find a Zoom link with the credentials for the talk:
Sujet: Réunion Zoom de Vladimir ROUBTSOV
Heure: 13 mars 2026 02:45 PM Paris
https://cnrs.zoom.us/j/98130850395?pwd=kfinrm6rM3hsWrzT5bL1yf1Rwhq6Is.1
ID de réunion: 981 3085 0395
Code secret: ZtqN8q
With best regards,
`Équations différentielles motiviques et au-delà’
============
Title: Сategorical quantizations of symplectic varieties in char p
Abstract: Originally motivated by physics, mathematically a quantization of a Poisson variety X is simply a formal 1-parameter deformation of its sheaf of functions that in the first approximation agrees with the Poisson bracket. In the algebraic context such quantizations tend not to exist globally due to a possible non-vanishing of cohomology of relevant coherent sheaves. It was observed by Kontsevich that in the algebraic context it might in fact be more natural to consider formal deformations of the category QCoh(X) rather than the sheaf of algebras O_X. I will talk about joint work with Bogdanova, Travkin and Vologodsky where, building on the work of Bezrukavnikov and Kaledin, we construct a canonical such categorical quantization for (restricted) symplectic varieties in char p. An interesting feature of char p is that this quantization in fact naturally extends from the formal disk to a family of categories over P^1 which carries strong resemblance with the Simpson’s twistor space picture. This allows to associate to any restricted symplectic scheme a category of "mod p F-gauges", which agrees with Bhatt-Lurie F-gauges for Y in the case X=T^*Y. If time permits I will also talk about some further results about quantizations over Z/p^n or even Z (work in progress).
via @EmailGateBot
[News GDR EFI] Séminaire Différentiel - 14 avril 2026 à l'IHP
Chères et chers collègues,
La prochaine journée du Séminaire Différentiel aura lieu le mardi 14 avril 2026 à l'IHP (!)
Les orateurs de la journée seront Veronica Fantini, Kilian Raschel et Sergey Yurkevich.
Vous trouverez plus d'informations sur la page du séminaire : http://divizio.joomla.com/sem-diff
Si vous souhaitez participer au déjeuner, il faut impérativement s'inscrire eu utilisant le formulaire avant le 10 avril :
https://framaforms.org/inscription-a-la-journee-du-seminaire-differentiel-du-14-avril-2026-a-lihp-1773829209
N'hésitez pas à diffuser ce message.
À bientôt, Les organisateurs, Alin Bostan et Lucia Di Vizio
[News GDR EFI] Séminaire Différentiel - 14 avril 2026 à l'IHP
Chères et chers collègues,
La prochaine journée du Séminaire Différentiel aura lieu le mardi 14 avril 2026 à l'IHP (!)
Les orateurs de la journée seront Veronica Fantini, Kilian Raschel et Sergey Yurkevich.
Vous trouverez plus d'informations sur la page du séminaire : http://divizio.joomla.com/sem-diff
Si vous souhaitez participer au déjeuner, il faut impérativement s'inscrire eu utilisant le formulaire avant le 10 avril :
https://framaforms.org/inscription-a-la-journee-du-seminaire-differentiel-du-14-avril-2026-a-lihp-1773829209
N'hésitez pas à diffuser ce message.
À bientôt, Les organisateurs, Alin Bostan et Lucia Di Vizio
🐳2
via @EmailGateBot
[News GDR EFI] S'eminiare "ED motiviques et au-del'a", IHP 27.03,
Expos'e de Bruno Vallette.
Dear All,
There will be a talk by Bruno Vallette (Université Sorbonne Paris Nord) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 27 March at 15:00 ( https://indico.math.cnrs.fr/event/16351/ )
Please find a zoom link with the credentials for the talk:
GdT Paris
Time: Mar 27, 2026 02:45 PM Paris
https://us02web.zoom.us/j/89420540841?pwd=XPcxGlZM0jfidwqWS06jyXn3N2S53y.1
Meeting ID: 894 2054 0841
Passcode: 069402
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: Integration theory of Lie type algebras
Abstract: I will survey the recent developments made in the integration theory with effective formulas of algebraic structures stronger or higher than Lie algebras. On the stronger side, one can integrate efficiently the pre-Lie algebras and admissible Lie algebras controlling the deformation theories of algebras over an operad and bialgebras over a properad respectively. On the higher side, I will describe how one can integration L_infinity-algebras into infinity-groupoids with closed formulas.
[News GDR EFI] S'eminiare "ED motiviques et au-del'a", IHP 27.03,
Expos'e de Bruno Vallette.
Dear All,
There will be a talk by Bruno Vallette (Université Sorbonne Paris Nord) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 27 March at 15:00 ( https://indico.math.cnrs.fr/event/16351/ )
Please find a zoom link with the credentials for the talk:
GdT Paris
Time: Mar 27, 2026 02:45 PM Paris
https://us02web.zoom.us/j/89420540841?pwd=XPcxGlZM0jfidwqWS06jyXn3N2S53y.1
Meeting ID: 894 2054 0841
Passcode: 069402
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: Integration theory of Lie type algebras
Abstract: I will survey the recent developments made in the integration theory with effective formulas of algebraic structures stronger or higher than Lie algebras. On the stronger side, one can integrate efficiently the pre-Lie algebras and admissible Lie algebras controlling the deformation theories of algebras over an operad and bialgebras over a properad respectively. On the higher side, I will describe how one can integration L_infinity-algebras into infinity-groupoids with closed formulas.
via @EmailGateBot
[News GDR EFI] Expose L. Di Vizio, Séminaire ED motivique et au dela, 10.04. 2026
Dear All,
There will be a talk by Lucia Di Vizio (Laboratoire de Mathématiques de Versailles) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 10 April at 15:00 ( https://indico.math.cnrs.fr/event/16410/ )
Please find a zoom link with the credentials for the talk:
Time: Apr 10, 2026 03:00 PM Paris
https://us02web.zoom.us/j/84318418541?pwd=55j17hsDo6sIIyhGEQtDuvhR1SnaJ2.1
Meeting ID: 843 1841 8541
Passcode: 135923
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: The Carlitz module and a differential Ax-Lindemann-Weierstrass theorem for the Euler gamma function
Abstract: We prove an Ax-Lindemann-Weierstrass differential transcendence result for Euler's gamma function, namely that the functions Γ(ν-ζ1(ν)),…, Γ(ν-ζn(ν)) are differentially independent over the field of rational functions in the variable ν, with coefficients in the field k of 1-periodic meromorphic functions over the complex numbers, as soon as ζ1,…, ζn determine a set of algebraic functions over k, stable by conjugation and pairwise distinct modulo the integers.
To prove this result we use both the Galois theory of difference equations and the theory of a characteristic zero analog of the Carlitz module introduced by the second author in 2013. As an intermediate result we give an explicit description of the Picard-Vessiot rings and of the Galois groups associated to the operators in the image of the Carlitz module, using techniques inspired by the Carlitz-Hayes theory. This is a joint work with Federico Pellarin.
[News GDR EFI] Expose L. Di Vizio, Séminaire ED motivique et au dela, 10.04. 2026
Dear All,
There will be a talk by Lucia Di Vizio (Laboratoire de Mathématiques de Versailles) at the IHP, salle Olga Ladyjenskaïa (ground floor), on Friday 10 April at 15:00 ( https://indico.math.cnrs.fr/event/16410/ )
Please find a zoom link with the credentials for the talk:
Time: Apr 10, 2026 03:00 PM Paris
https://us02web.zoom.us/j/84318418541?pwd=55j17hsDo6sIIyhGEQtDuvhR1SnaJ2.1
Meeting ID: 843 1841 8541
Passcode: 135923
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: The Carlitz module and a differential Ax-Lindemann-Weierstrass theorem for the Euler gamma function
Abstract: We prove an Ax-Lindemann-Weierstrass differential transcendence result for Euler's gamma function, namely that the functions Γ(ν-ζ1(ν)),…, Γ(ν-ζn(ν)) are differentially independent over the field of rational functions in the variable ν, with coefficients in the field k of 1-periodic meromorphic functions over the complex numbers, as soon as ζ1,…, ζn determine a set of algebraic functions over k, stable by conjugation and pairwise distinct modulo the integers.
To prove this result we use both the Galois theory of difference equations and the theory of a characteristic zero analog of the Carlitz module introduced by the second author in 2013. As an intermediate result we give an explicit description of the Picard-Vessiot rings and of the Galois groups associated to the operators in the image of the Carlitz module, using techniques inspired by the Carlitz-Hayes theory. This is a joint work with Federico Pellarin.
via @EmailGateBot
[News GDR EFI] Séminaire "ED Motiviques et au-dela"Expose de Fernando Rodriguez Villegas at the IHP, 24.04.2026
Dear All,
There will be a talk by Fernando Rodriguez Villegas at the IHP, salle Marie-Louise Dubreil-Jacotin, on Friday 24 April at 15:00 ( https://indico.math.cnrs.fr/event/16461/ )
Please find a zoom link with the credentials for the talk:
Time: Apr 24, 2026 02:45 PM Paris
https://us02web.zoom.us/j/88660590014?pwd=G729s0UKwMnqSo3fV1bXpltzEnQtYI.1
Meeting ID: 886 6059 0014
Passcode: 482670
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: Motivic local systems
Abstract: I will discuss a motivic version of Mellin's expansion for the roots of a generic one-variable polynomial with fixed monomials. This leads to examples of explicit forms of the trace of Frobenius for certain non-hypergeometric rigid local systems.
[News GDR EFI] Séminaire "ED Motiviques et au-dela"Expose de Fernando Rodriguez Villegas at the IHP, 24.04.2026
Dear All,
There will be a talk by Fernando Rodriguez Villegas at the IHP, salle Marie-Louise Dubreil-Jacotin, on Friday 24 April at 15:00 ( https://indico.math.cnrs.fr/event/16461/ )
Please find a zoom link with the credentials for the talk:
Time: Apr 24, 2026 02:45 PM Paris
https://us02web.zoom.us/j/88660590014?pwd=G729s0UKwMnqSo3fV1bXpltzEnQtYI.1
Meeting ID: 886 6059 0014
Passcode: 482670
With best regards,
`Équations différentielles motiviques et au–delà’
============================================
Title: Motivic local systems
Abstract: I will discuss a motivic version of Mellin's expansion for the roots of a generic one-variable polynomial with fixed monomials. This leads to examples of explicit forms of the trace of Frobenius for certain non-hypergeometric rigid local systems.
via @EmailGateBot
[News GDR EFI] Cours d'introduction à lathéorie de Galois différentiellepar Lucia Di Vizio
Chères collègues, chers collègues,En mai prochain, Lucia Di Vizio (CNRS, Université de VersaillesSaint-Quentin) donnera un cours (en huit séances) d'introduction à lathéorie de Galois différentielle à l'Université de La Sapienza. Ce courssera retransmis par zoom à l'adresse :https://uvsq-fr.zoom.us/my/luciadv?pwd=VVVnanZmUFJmVUZEcjRiZFVTYlRrUT09La description du cours est disponible ici :https://www.mat.uniroma1.it/sites/default/files/evento/node-4410/corso_roma.pdfLes séances actuellement programmées sont les 4, 5, 11, 12, 18, 19 et 26mai entre 10h et approximativement midi.Venez nombreuses et nombreux !Bien à vous,Federico Pellarin-- *Fai crescere le giovani ricercatrici e i giovani ricercatori****con il 5 per mille alla Sapienza*Scrivi il codice fiscale dell'Università *80209930587**Cinque per mille * Chères collègues, chers collègues,
En mai prochain, Lucia Di Vizio (CNRS, Université de Versailles Saint-Quentin) donnera un cours (en huit séances) d'introduction à la théorie de Galois différentielle à l'Université de La Sapienza. Ce cours sera retransmis par zoom à l'adresse :
https://uvsq-fr.zoom.us/my/luciadv?pwd=VVVnanZmUFJmVUZEcjRiZFVTYlRrUT09
La description du cours est disponible ici : https://www.mat.uniroma1.it/sites/default/files/evento/node-4410/corso_roma.pdf
Les séances actuellement programmées sont les 4, 5, 11, 12, 18, 19 et 26 mai entre 10h et approximativement midi.
Venez nombreuses et nombreux !
Bien à vous, Federico Pellarin
Fai crescere le giovani ricercatrici e i giovani ricercatori
con il 5 per mille alla Sapienza
Scrivi il codice fiscale dell'Università 80209930587
Cinque per mille
[News GDR EFI] Cours d'introduction à lathéorie de Galois différentiellepar Lucia Di Vizio
Chères collègues, chers collègues,En mai prochain, Lucia Di Vizio (CNRS, Université de VersaillesSaint-Quentin) donnera un cours (en huit séances) d'introduction à lathéorie de Galois différentielle à l'Université de La Sapienza. Ce courssera retransmis par zoom à l'adresse :https://uvsq-fr.zoom.us/my/luciadv?pwd=VVVnanZmUFJmVUZEcjRiZFVTYlRrUT09La description du cours est disponible ici :https://www.mat.uniroma1.it/sites/default/files/evento/node-4410/corso_roma.pdfLes séances actuellement programmées sont les 4, 5, 11, 12, 18, 19 et 26mai entre 10h et approximativement midi.Venez nombreuses et nombreux !Bien à vous,Federico Pellarin-- *Fai crescere le giovani ricercatrici e i giovani ricercatori****con il 5 per mille alla Sapienza*Scrivi il codice fiscale dell'Università *80209930587**Cinque per mille * Chères collègues, chers collègues,
En mai prochain, Lucia Di Vizio (CNRS, Université de Versailles Saint-Quentin) donnera un cours (en huit séances) d'introduction à la théorie de Galois différentielle à l'Université de La Sapienza. Ce cours sera retransmis par zoom à l'adresse :
https://uvsq-fr.zoom.us/my/luciadv?pwd=VVVnanZmUFJmVUZEcjRiZFVTYlRrUT09
La description du cours est disponible ici : https://www.mat.uniroma1.it/sites/default/files/evento/node-4410/corso_roma.pdf
Les séances actuellement programmées sont les 4, 5, 11, 12, 18, 19 et 26 mai entre 10h et approximativement midi.
Venez nombreuses et nombreux !
Bien à vous, Federico Pellarin
Fai crescere le giovani ricercatrici e i giovani ricercatori
con il 5 per mille alla Sapienza
Scrivi il codice fiscale dell'Università 80209930587
Cinque per mille
via @EmailGateBot
[News GDR EFI] Invitation to my PhD Defense
Dear colleagues,
It is my pleasure to invite you to the defense of my PhD thesis, titled
"Arithmetic and Effective Aspects of Linear Differential Equations",
prepared under the supervision of Alin Bostan (INRIA) and Christian
Krattenthaler (U. Vienna).
The defense takes place on July 2nd, at 2.30 pm, in Vienna, and will be
transmitted under the following zoom link:
https://univienna.zoom.us/j/64774477407?pwd=Zo9nuBtWNbegNuCWIyYqvkaaL5oFHa.1
My thesis can be found here:
https://homepage.univie.ac.at/florian.fuernsinn/wp-content/uploads/2026/04/Final2.pdf,
and enclosed to this message you find its abstract. The jury is
comprised as follows:
-) Alin Bostan (INRIA, advisor)
-) Javier Fresán (Sorbonne U., reviewer)
-) Ulisse Stefanelli (U. Vienna, chair)
-) Jacques-Arthur Weil (U. Limoges, reviewer)
I am looking forward to seeing many of you next Thursday online!
Best wishes,
Florian (Fürnsinn)
Abstract:
Determining whether the solutions of ordinary linear differential
equations with polynomial coefficients are algebraic functions, is an
old question, already asked by Fuchs and Liouville in the mid-19th
century. In 1980 Stanley asked for an algorithm, suitable for computer
implementation, that accomplished this task. A partial answer to this
question was given by Singer, giving an algorithm to answer the
question, but involving bounds that make it not suitable for
implementation.
A different, arithmetic, approach to the question was proposed by
Grothendieck in the late 1960s. To each differential equation one can
attach for any prime number p a linear map, the p-curvature. He
conjectured an equivalence between the algebraicity of a basis of
solutions of a differential equation, and the vanishing of the
p-curvature for almost all prime numbers p. The vanishing of the
p-curvature is also equivalent to the existence of a full basis of
solutions of the differential equation in positive characteristic.
This thesis addresses several questions related to Stanley’s question
and Grothendieck’s conjecture, and mainly consists of papers and
preprints of the author. We develop a local solution theory for
differential equations in positive characteristic, similar to the
Fuchs-Frobenius method, and we investigate algebraicity properties of
the solutions obtained. Moreover, we complete the classification of
algebraic hypergeometric functions initiated by Christol, and Beukers
and Heckman. We propose a conjecture about the Galois groups of
algebraic reductions modulo primes of solutions of differential
equations, a local-global principle similar to the Grothendieck
conjecture. Motivated by this conjecture, we compute the Galois groups
of the reductions of generating functions of Apéry-like sequences modulo
primes. Following Honda and the Chudnovsky brothers, we prove an
effective version of the Grothendieck p-curvature conjecture for order
one equations, giving a new partial answer to Stanley’s question.
Moreover, we develop new algorithms for arithmetic and algebraic
properties of hypergeometric functions that help us test conjectures in
this orbit, and discuss an implementation in the computer algebra system
SageMath.
[News GDR EFI] Invitation to my PhD Defense
Dear colleagues,
It is my pleasure to invite you to the defense of my PhD thesis, titled
"Arithmetic and Effective Aspects of Linear Differential Equations",
prepared under the supervision of Alin Bostan (INRIA) and Christian
Krattenthaler (U. Vienna).
The defense takes place on July 2nd, at 2.30 pm, in Vienna, and will be
transmitted under the following zoom link:
https://univienna.zoom.us/j/64774477407?pwd=Zo9nuBtWNbegNuCWIyYqvkaaL5oFHa.1
My thesis can be found here:
https://homepage.univie.ac.at/florian.fuernsinn/wp-content/uploads/2026/04/Final2.pdf,
and enclosed to this message you find its abstract. The jury is
comprised as follows:
-) Alin Bostan (INRIA, advisor)
-) Javier Fresán (Sorbonne U., reviewer)
-) Ulisse Stefanelli (U. Vienna, chair)
-) Jacques-Arthur Weil (U. Limoges, reviewer)
I am looking forward to seeing many of you next Thursday online!
Best wishes,
Florian (Fürnsinn)
Abstract:
Determining whether the solutions of ordinary linear differential
equations with polynomial coefficients are algebraic functions, is an
old question, already asked by Fuchs and Liouville in the mid-19th
century. In 1980 Stanley asked for an algorithm, suitable for computer
implementation, that accomplished this task. A partial answer to this
question was given by Singer, giving an algorithm to answer the
question, but involving bounds that make it not suitable for
implementation.
A different, arithmetic, approach to the question was proposed by
Grothendieck in the late 1960s. To each differential equation one can
attach for any prime number p a linear map, the p-curvature. He
conjectured an equivalence between the algebraicity of a basis of
solutions of a differential equation, and the vanishing of the
p-curvature for almost all prime numbers p. The vanishing of the
p-curvature is also equivalent to the existence of a full basis of
solutions of the differential equation in positive characteristic.
This thesis addresses several questions related to Stanley’s question
and Grothendieck’s conjecture, and mainly consists of papers and
preprints of the author. We develop a local solution theory for
differential equations in positive characteristic, similar to the
Fuchs-Frobenius method, and we investigate algebraicity properties of
the solutions obtained. Moreover, we complete the classification of
algebraic hypergeometric functions initiated by Christol, and Beukers
and Heckman. We propose a conjecture about the Galois groups of
algebraic reductions modulo primes of solutions of differential
equations, a local-global principle similar to the Grothendieck
conjecture. Motivated by this conjecture, we compute the Galois groups
of the reductions of generating functions of Apéry-like sequences modulo
primes. Following Honda and the Chudnovsky brothers, we prove an
effective version of the Grothendieck p-curvature conjecture for order
one equations, giving a new partial answer to Stanley’s question.
Moreover, we develop new algorithms for arithmetic and algebraic
properties of hypergeometric functions that help us test conjectures in
this orbit, and discuss an implementation in the computer algebra system
SageMath.