We analyze deep Neural Network emulation rates of smooth functions with point singularities in bounded, polytopal domains $\mathrm{D} \subset \mathbb{R}^d$, $d=2,3$. We prove exponential emulation rates in Sobolev spaces in terms of the number of neurons and in terms of the number of nonzero coefficients for Gevrey-regular solution classes defined in terms of weighted Sobolev scales in $\mathrm{D}$, comprising the countably-normed spaces of I.M. Babu\v{s}ka and B.Q. Guo. As intermediate result, we prove that continuous, piecewise polynomial high order (``$p$-version'') finite elements with elementwise polynomial degree $p\in\mathbb{N}$ on arbitrary, regular, simplicial partitions of polyhedral domains $\mathrm{D} \subset \mathbb{R}^d$, $d\geq 2$ can be exactly emulated by neural networks combining ReLU and ReLU$^2$ activations. On shape-regular, simplicial partitions of polytopal domains $\mathrm{D}$, both the number of neurons and the number of nonzero parameters are proportional to the number of degrees of freedom of the finite element space, in particular for the $hp$-Finite Element Method of I.M. Babu\v{s}ka and B.Q. Guo.
翻译:我们分析了在有限多面体区域$\mathrm{D} \subset \mathbb{R}^d$($d=2,3$)中,深度神经网络对含点奇点光滑函数的逼近率。针对由$\mathrm{D}$中加权Sobolev尺度定义的Gevrey正则解类(包括I.M. Babu\v{s}ka和B.Q. Guo的可数赋范空间),我们证明了在神经元数量和基于非零系数数量的Sobolev空间指数级逼近率。作为中间结果,我们证明了对于$\mathbb{R}^d$($d\geq 2$)中多面体区域$\mathrm{D}$的任意正则单纯形剖分,阶数为$p\in\mathbb{N}$的连续分片多项式高阶("$p$版本")有限元可通过结合ReLU和ReLU$^2$激活函数的神经网络精确模拟。在$\mathrm{D}$的形状正则单纯形剖分上,神经元数量和非零参数数量均与有限元空间的自由度数量成正比,尤其适用于I.M. Babu\v{s}ka和B.Q. Guo提出的$hp$有限元方法。