What they are calling "Symmetric Delete" seems to be the same as an older concept called "deletion neighborhoods". It is a term coined in an academic paper written by Thomas Bocek, Ela Hunt, and Burkhard Stiller from the University of Zurich, titled "Fast Similarity Search in Large Dictionaries"[1]. The work described there was expanded in a paper written by Daniel Karch, Dennis Luxen, and Peter Sanders from the Karlsruhe Institute of Technology, titled "Improved Fast Similarity Search in Dictionaries"[2]. Both of these papers deal with efficient searching for similar string values, given a query string.<p>LookupCompound and WordSegmentation, algorithms built on Symmetric Delete/Deletion Neighborhoods, are pretty interesting.<p>[1]<a href="https://fastss.csg.uzh.ch/ifi-2007.02.pdf" rel="nofollow">https://fastss.csg.uzh.ch/ifi-2007.02.pdf</a>
[2]<a href="https://arxiv.org/abs/1008.1191v2" rel="nofollow">https://arxiv.org/abs/1008.1191v2</a>