Khalef Yaddaden

I am a temporary research and teaching assistant at University of Caen Normandy (France). I teach within the UFR des Sciences, and I am a member of the GRAAL research team at the Laboratoire de Mathématiques Nicolas Oresme.

Before that I was a JSPS Postdoctoral Research fellow in the Graduate School of Mathematics of Nagoya University (Japan) under Professor Hidekazu Furusho.

I did my Ph.D. in mathematics at the University of Strasbourg (France) under the supervision of Professor Benjamin Enriquez.

I am interested in various aspects of multiple zeta values, their cyclotomic analogues the multiple polylogarithm values at roots of unity and their connections to associators and Grothendieck-Teïchmuller theory.

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Selected publications

On a conjecture of Zhao related to standard relations among cyclotomic multiple zeta values

Henrik Bachmann, and Khalef Yaddaden

Journal of Algebra, 2026

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We provide a proof of a conjecture by Zhao concerning the structure of certain relations among cyclotomic multiple zeta values in weight two. We formulate this conjecture in a broader algebraic setting in which we give a natural equivalence between two schemes attached to a finite abelian group G. In particular, when G is the group of roots of unity, these schemes describe the standard relations among cyclotomic multiple zeta values.
@article{by, title = {On a conjecture of Zhao related to standard relations among cyclotomic multiple zeta values}, author = {Bachmann, Henrik and Yaddaden, Khalef}, journal = {Journal of Algebra}, volume = {688}, pages = {21-58}, year = {2026}, doi = {https://doi.org/10.1016/j.jalgebra.2025.10.003}, url = {https://www.sciencedirect.com/science/article/pii/S0022314X2500174X}, }
The cyclotomic double shuffle torsor in terms of Betti and de Rham coproducts

Khalef Yaddaden

Journal of Pure and Applied Algebra, 2024

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We prove a cyclotomic generalization of Enriquez and Furusho’s result stating that the scheme of double shuffle and regularization relations between multiple zeta values arising from Racinet’s formalism is a torsor of isomorphisms between “Betti” and “de Rham” objects. After reviewing the “de Rham” objects arising from a crossed product interpretation of Racinet’s formalism, we construct the “Betti” objects based on an orbifold fundamental group. We then show that the scheme of double shuffle and regularization relations is a subtorsor of stabilizer schemes relating “Betti” and “de Rham” coproducts.
@article{yad2, title = {The cyclotomic double shuffle torsor in terms of Betti and de Rham coproducts}, author = {Yaddaden, Khalef}, journal = {Journal of Pure and Applied Algebra}, volume = {228}, number = {5}, pages = {Paper No. 107550, 66}, year = {2024}, doi = {https://doi.org/10.1016/j.jpaa.2023.107550}, url = {https://www.sciencedirect.com/science/article/pii/S0022404923002323}, }