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math.RA2026
Boundary Cochains and the Toeplitz Index on the Half-Lattice
Nassim Athmouni
We study the operator algebra of a rank-one boundary defect in a semi-infinite tight-binding chain, on , with the forward unilat…
math.RA2025
Explicit Baker--Campbell--Hausdorff Radii in Special Banach--Malcev Algebras of Shifts
Nassim Athmouni
We establish explicit convergence radii for the Baker--Campbell--Hausdorff (BCH) series in special Banach--Malcev algebras of shifts-those embeddable into a Banach alternative alge…
math.RA2025
Local Rigidity of Quasi--Lie Brackets on Quaternionic Banach Modules and Applications to Nonlinear PDEs
Nassim Athmouni
We establish a local rigidity theorem for quasi--Lie brackets on quaternionic Banach right modules. Under quantitative control of antisymmetry and Jacobi defects, we construct an e…