Stochastic gradient descent with noise of machine learning type part i: Discrete time analysis
S Wojtowytsch - Journal of Nonlinear Science, 2023 - Springer
Stochastic gradient descent (SGD) is one of the most popular algorithms in modern machine
learning. The noise encountered in these applications is different from that in many …
learning. The noise encountered in these applications is different from that in many …
On the cut locus of free, step two Carnot groups
In this note, we study the cut locus of the free, step two Carnot groups $\mathbb {G} _k $ with
$ k $ generators, equipped with their left-invariant Carnot-Carathéodory metric. In particular …
$ k $ generators, equipped with their left-invariant Carnot-Carathéodory metric. In particular …
Comparison theorems for conjugate points in sub-Riemannian geometry
D Barilari, L Rizzi - ESAIM: Control, Optimisation and Calculus of …, 2016 - numdam.org
We prove sectional and Ricci-type comparison theorems for the existence of conjugate
points along sub-Riemannian geodesics. In order to do that, we regard sub-Riemannian …
points along sub-Riemannian geodesics. In order to do that, we regard sub-Riemannian …
Stochastic gradient descent with noise of machine learning type part II: Continuous time analysis
S Wojtowytsch - Journal of Nonlinear Science, 2024 - Springer
The representation of functions by artificial neural networks depends on a large number of
parameters in a non-linear fashion. Suitable parameters are found by minimizing a 'loss …
parameters in a non-linear fashion. Suitable parameters are found by minimizing a 'loss …
Curvature terms in small time heat kernel expansion for a model class of hypoelliptic Hörmander operators
D Barilari, E Paoli - Nonlinear Analysis, 2017 - Elsevier
We consider the heat equation associated with a class of second order hypoelliptic
Hörmander operators with constant second order term and linear drift. We completely …
Hörmander operators with constant second order term and linear drift. We completely …
Sub-Riemannian Ricci curvatures and universal diameter bounds for 3-Sasakian manifolds
L Rizzi, P Silveira - Journal of the Institute of Mathematics of Jussieu, 2019 - cambridge.org
For a fat sub-Riemannian structure, we introduce three canonical Ricci curvatures in the
sense of Agrachev–Zelenko–Li. Under appropriate bounds we prove comparison theorems …
sense of Agrachev–Zelenko–Li. Under appropriate bounds we prove comparison theorems …
Side Boundary potentials for a Kolmogorov-type PDE
R Sowers - arXiv preprint arXiv:2306.16548, 2023 - arxiv.org
We solve a Kolmogorov-type hypoelliptic parabolic partial differential equation with a\lq\lq
side" boundary condition (in the direction of the weak H\" ormander condition). We construct …
side" boundary condition (in the direction of the weak H\" ormander condition). We construct …
Short geodesics losing optimality in contact sub-Riemannian manifolds and stability of the 5-dimensional caustic
L Sacchelli - SIAM Journal on Control and Optimization, 2019 - SIAM
We study the sub-Riemannian exponential for contact distributions on manifolds of
dimension greater than or equal to 5. We compute an approximation of the sub-Riemannian …
dimension greater than or equal to 5. We compute an approximation of the sub-Riemannian …
Heat kernel asymptotics on sub-Riemannian manifolds with symmetries and applications to the bi-Heisenberg group
By adapting a technique of Molchanov, we obtain the heat kernel asymptotics at the sub-
Riemannian cut locus, when the cut points are reached by an r-dimensional parametric …
Riemannian cut locus, when the cut points are reached by an r-dimensional parametric …
Local (sub)-Finslerian geometry for the maximum norms in dimension 2
EAL Ali, G Charlot - Journal of Dynamical and Control Systems, 2019 - Springer
We consider specific sub-Finslerian structures in the neighborhood of 0 in ℝ 2 R^2, defined
by fixing a family of vector fields (F 1, F 2) and considering the norm defined on the non …
by fixing a family of vector fields (F 1, F 2) and considering the norm defined on the non …