In the last three decades, powerful computer-assisted techniques have been developed in order to validate a posteriori numerical solutions of semilinear elliptic problems of the form $Δu +f(u,\nabla u) = 0$. By studying a well chosen fixed point problem defined around the numerical solution, these techniques make it possible to prove the existence of a solution in an explicit (and usually small) neighborhood the numerical solution. In this work, we develop a similar approach for a broader class of systems, including nonlinear diffusion terms of the form $ΔΦ(u)$. In particular, this enables us to obtain new results about steady states of a cross-diffusion system from population dynamics: the (non-triangular) SKT model. We also revisit the idea of automatic differentiation in the context of computer-assisted proof, and propose an alternative approach based on differential-algebraic equations.
Computer-Assisted Proof of the Main Theorem of 'The Classification of Branched Willmore Spheres in the $3$-Sphere and the $4$-Sphere'
我们使用免费的数学软件Sage对论文“The Classification of Branched Willmore spheres in the $3$ -Sphere and the $4$ -Sphere”(arXiv:1706.01405)中的主要定理4.11中的四次和八次亚纯微分的全纯性进行了计算机辅助证明。
A computer-assisted existence proof for Emden's equation on an unbounded L-shaped domain
我们证明了存在性,非退化,并在无穷远的非平凡的解决方案埃姆登的方程$-Δu = | u |^3$上的一个无界的$L$形域,Dirichlet边界条件的指数衰减。除了这个结果的直接价值,我们也把这个解决方案作为一个积木的解决方案扩大有界域的角落,建立在未来的工作。我们的证明大量使用计算机辅助:从一个数值近似解开始,我们使用一个不动点参数来证明附近的精确解的存在性。在证明过程中建立的特征值界也意味着解的非退化性。
Computer-assisted proof of heteroclinic connections in the one-dimensional Ohta-Kawasaki model
Institute of Computer Science and Computational Mathematics, Jagiellonian University(雅盖隆大学计算机科学与计算数学研究所);Institute of Applied Mathematics and Mechanics, University of Warsaw(华沙大学应用数学与力学研究所);Department of Mathematics, Rutgers, The State University of New Jersey(新泽西州立大学罗格斯大学数学系);Department of Mathematical Sciences, George Mason University(乔治梅森大学数学科学系)
On the potential lack of response in a model of second-harmonic generation. A computer-assisted proof
School of Mathematical and Statistical Sciences, University of Texas Rio Grande Valley(德克萨斯大学里奥格兰德河谷分校数学与统计科学学院);Department of Mathematics, Rutgers University(罗格斯大学数学系);Department of Mathematics and Statistics, McGill University(麦吉尔大学数学与统计系)