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 writ

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. LookupCompound and WordSegmentation, algorithms built on Symmetric Delete/Deletion Neighborhoods, are pretty interesting. [1]https://fastss.csg.uzh.ch/ifi-2007.02.pdf https://fastss.csg.uzh.ch/ifi-2007.02.pdf [2]https://arxiv.org/abs/1008.1191v2 https://arxiv.org/abs/1008.1191v2