Universal approximation theorem: Difference between revisions

Content deleted Content added
TristanDC (talk | contribs)
m disambiguate what looks like differentials
mNo edit summary
Line 101:
 
== Arbitrary-depth case ==
The "dual" versions of the theorem consider networks of bounded width and arbitrary depth. A variant of the universal approximation theorem was proved for the arbitrary depth case by Zhou Lu et al. in 2017.<ref name=ZhouLu /> They showed that networks of width ''n''&nbsp;+&nbsp;4 with [[ReLU]] activation functions can approximate any [[Lebesgue integration|Lebesgue-integrable function]] on ''n''-dimensional input space with respect to [[L1 distance|<math>L^1</math> distance]] if network depth is allowed to grow. It was also shown that if the width was less than or equal to ''n'', this general expressive power to approximate any Lebesgue integrable function was lost. In the same paper<ref name=ZhouLu /> it was shown that [[ReLU]] networks with width ''n''&nbsp;+&nbsp;1 were sufficient to approximate any [[continuous function|continuous]] function of ''n''-dimensional input variables.<ref>Hanin, B. (2018). [[arxiv:1710.11278|Approximating Continuous Functions by ReLU Nets of Minimal Width]]. arXiv preprint arXiv:1710.11278.<name=hanin/ref> The following refinement, specifies the optimal minimum width for which such an approximation is possible and is due to.<ref>{{Cite journal |last=Park, Yun, Lee, Shin |first=Sejun, Chulhee, Jaeho, Jinwoo |date=2020-09-28 |title=Minimum Width for Universal Approximation |url=https://openreview.net/forum?id=O-XJwyoIF-k |journal=ICLR |arxiv=2006.08859 |language=en}}</ref>
 
{{math theorem