Editing 2-satisfiability (section)

===Many-valued logics===
The 2-satisfiability problem can also be asked for propositional [[many-valued logic]]s. The algorithms are not usually linear, and for some logics the problem is even NP-complete. See {{harvs|last=Hähnle|year=2001|year2=2003|txt}} for surveys.<ref>{{citation|editor1-first=Dov M.|editor1-last=Gabbay|editor2-first=Franz|editor2-last=Günthner|title=Handbook of Philosophical Logic|year=2001|publisher=Springer|isbn=978-94-017-0452-6|pages=297–395|chapter=Advanced many-valued logics|first=Reiner|last=Hähnle|volume=2|doi=10.1007/978-94-017-0452-6_5}} (see in particular [https://books.google.com/books?id=_ol81ow-1s4C&pg=PA373 p.&nbsp;373]); {{citation|editor1-first=Melvin|editor1-last=Fitting|editor2-first=Ewa|editor2-last=Orlowska|editor2-link= Ewa Orłowska |title=Beyond two: theory and applications of multiple-valued logic|year=2003|publisher=Springer|isbn=978-3-7908-1541-2|first=Reiner|last=Hähnle|chapter=Complexity of Many-valued Logics|doi=10.1007/978-3-7908-1769-0_9|series=Studies in Fuzziness and Soft Computing|volume=114|pages=211–233}}</ref>