The currently fastest algorithm for regular expression pattern matching and membership improves the classical O(nm) time algorithm by a factor of about log^{3/2}n. Instead of focussing on general patterns we analyse homogeneous patterns of bounded depth in this work. For them a classification splitting the types in easy (strongly sub-quadratic) and hard (essentially quadratic time under SETH) is known. We take a very fine-grained look at the hard pattern types from this classification and show a dichotomy: few types allow super-poly-logarithmic improvements while the algorithms for the other pattern types can only be improved by a constant number of log-factors, assuming the Formula-SAT Hypothesis.
@InProceedings{schepper:LIPIcs.ESA.2020.80, author = {Schepper, Philipp}, title = {{Fine-Grained Complexity of Regular Expression Pattern Matching and Membership}}, booktitle = {28th Annual European Symposium on Algorithms (ESA 2020)}, pages = {80:1--80:20}, series = {Leibniz International Proceedings in Informatics (LIPIcs)}, ISBN = {978-3-95977-162-7}, ISSN = {1868-8969}, year = {2020}, volume = {173}, editor = {Grandoni, Fabrizio and Herman, Grzegorz and Sanders, Peter}, publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik}, address = {Dagstuhl, Germany}, URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ESA.2020.80}, URN = {urn:nbn:de:0030-drops-129464}, doi = {10.4230/LIPIcs.ESA.2020.80}, annote = {Keywords: Fine-Grained Complexity, Regular Expression, Pattern Matching, Dichotomy} }
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