2 papers
math.AP2026
Lack of Gevrey solvability for a model operator
Enrico Bernardi
We prove that the Cauchy problem for the model hyperbolic operator in \[ Q=-D_t^2+2xD_tD_y+D_x^2+x^3D_y^2+D_z^2+z^2D_y^2 \] is not locally solvable at the origin, in the…
math.ST2025
Large covariance matrix estimation via penalized log-det heuristics
Enrico Bernardi, Matteo Farnè
This paper provides a comprehensive estimation framework for large covariance matrices via a log-det heuristics augmented by a nuclear norm plus -norm penalty. We develop…