@article{11701,
  abstract     = {In this paper we develop a new approach to nonlinear stochastic partial differential equations with Gaussian noise. Our aim is to provide an abstract framework which is applicable to a large class of SPDEs and includes many important cases of nonlinear parabolic problems which are of quasi- or semilinear type. This first part is on local existence and well-posedness. A second part in preparation is on blow-up criteria and regularization. Our theory is formulated in an Lp-setting, and because of this we can deal with nonlinearities in a very efficient way. Applications to several concrete problems and their quasilinear variants are given. This includes Burgers' equation, the Allen–Cahn equation, the Cahn–Hilliard equation, reaction–diffusion equations, and the porous media equation. The interplay of the nonlinearities and the critical spaces of initial data leads to new results and insights for these SPDEs. The proofs are based on recent developments in maximal regularity theory for the linearized problem for deterministic and stochastic evolution equations. In particular, our theory can be seen as a stochastic version of the theory of critical spaces due to Prüss–Simonett–Wilke (2018). Sharp weighted time-regularity allow us to deal with rough initial values and obtain instantaneous regularization results. The abstract well-posedness results are obtained by a combination of several sophisticated splitting and truncation arguments.},
  author       = {Agresti, Antonio and Veraar, Mark},
  issn         = {1361-6544},
  journal      = {Nonlinearity},
  number       = {8},
  pages        = {4100--4210},
  publisher    = {IOP Publishing},
  title        = {{Nonlinear parabolic stochastic evolution equations in critical spaces Part I. Stochastic maximal regularity and local existence}},
  doi          = {10.1088/1361-6544/abd613},
  volume       = {35},
  year         = {2022},
}

@article{8420,
  abstract     = {We show that in the space of all convex billiard boundaries, the set of boundaries with rational caustics is dense. More precisely, the set of billiard boundaries with caustics of rotation number 1/q is polynomially sense in the smooth case, and exponentially dense in the analytic case.},
  author       = {Kaloshin, Vadim and Zhang, Ke},
  issn         = {0951-7715},
  journal      = {Nonlinearity},
  keywords     = {Mathematical Physics, General Physics and Astronomy, Applied Mathematics, Statistical and Nonlinear Physics},
  number       = {11},
  pages        = {5214--5234},
  publisher    = {IOP Publishing},
  title        = {{Density of convex billiards with rational caustics}},
  doi          = {10.1088/1361-6544/aadc12},
  volume       = {31},
  year         = {2018},
}

@article{8498,
  abstract     = {In the present note we announce a proof of a strong form of Arnold diffusion for smooth convex Hamiltonian systems. Let ${\mathbb T}^2$  be a 2-dimensional torus and B2 be the unit ball around the origin in ${\mathbb R}^2$ . Fix ρ > 0. Our main result says that for a 'generic' time-periodic perturbation of an integrable system of two degrees of freedom $H_0(p)+\varepsilon H_1(\theta,p,t),\quad \ \theta\in {\mathbb T}^2,\ p\in B^2,\ t\in {\mathbb T}={\mathbb R}/{\mathbb Z}$ , with a strictly convex H0, there exists a ρ-dense orbit (θε, pε, t)(t) in ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ , namely, a ρ-neighborhood of the orbit contains ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ .

Our proof is a combination of geometric and variational methods. The fundamental elements of the construction are the usage of crumpled normally hyperbolic invariant cylinders from [9], flower and simple normally hyperbolic invariant manifolds from [36] as well as their kissing property at a strong double resonance. This allows us to build a 'connected' net of three-dimensional normally hyperbolic invariant manifolds. To construct diffusing orbits along this net we employ a version of the Mather variational method [41] equipped with weak KAM theory [28], proposed by Bernard in [7].},
  author       = {Kaloshin, Vadim and Zhang, K},
  issn         = {0951-7715},
  journal      = {Nonlinearity},
  keywords     = {Mathematical Physics, General Physics and Astronomy, Applied Mathematics, Statistical and Nonlinear Physics},
  number       = {8},
  pages        = {2699--2720},
  publisher    = {IOP Publishing},
  title        = {{Arnold diffusion for smooth convex systems of two and a half degrees of freedom}},
  doi          = {10.1088/0951-7715/28/8/2699},
  volume       = {28},
  year         = {2015},
}

@article{8527,
  abstract     = {We introduce a new potential-theoretic definition of the dimension spectrum  of a probability measure for q > 1 and explain its relation to prior definitions. We apply this definition to prove that if  and  is a Borel probability measure with compact support in , then under almost every linear transformation from  to , the q-dimension of the image of  is ; in particular, the q-dimension of  is preserved provided . We also present results on the preservation of information dimension  and pointwise dimension. Finally, for  and q > 2 we give examples for which  is not preserved by any linear transformation into . All results for typical linear transformations are also proved for typical (in the sense of prevalence) continuously differentiable functions.},
  author       = {Hunt, Brian R and Kaloshin, Vadim},
  issn         = {0951-7715},
  journal      = {Nonlinearity},
  keywords     = {Mathematical Physics, General Physics and Astronomy, Applied Mathematics, Statistical and Nonlinear Physics},
  number       = {5},
  pages        = {1031--1046},
  publisher    = {IOP Publishing},
  title        = {{How projections affect the dimension spectrum of fractal measures}},
  doi          = {10.1088/0951-7715/10/5/002},
  volume       = {10},
  year         = {1997},
}