Abstract
We introduce a new measure on regular languages: their nondeterministic syntactic complexity. It is the least degree of any extension of the ‘canonical boolean representation’ of the syntactic monoid. Equivalently, it is the least number of states of any subatomic nondeterministic acceptor. It turns out that essentially all previous structural work on nondeterministic state-minimality computes this measure. Our approach rests on an algebraic interpretation of nondeterministic finite automata as deterministic finite automata endowed with semilattice structure. Crucially, the latter form a self-dual category.
Footnotes
Stefan Milius–Supported by Deutsche Forschungsgemeinschaft (DFG) under projects MI 717/5-2 and MI 717/7-1, and as part of the Research and Training Group 2475 “Cybercrime and Forensic Computing” (393541319/GRK2475/1-2019)
Henning Urbat–Supported by Deutsche Forschungsgemeinschaft (DFG) under proj. SCHR 1118/8-2
Contributor Information
Stefan Kiefer, Email: stekie@cs.ox.ac.uk.
Christine Tasson, Email: christine.tasson@lip6.fr.
Robert S. R. Myers, Email: my.robmyers@gmail.com
Stefan Milius, Email: stefan.milius@fau.de.
Henning Urbat, Email: henning.urbat@fau.de.
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