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Some remarks on Došen's logic N and its extensions
Siberian Electronic Mathematical Reports. 2022. Vol. 19. No. 2. P. 562–577.
This paper collects some observations about Došen's logic N, where negation is treated as a modal operator, and its extensions. We shall see what happens when we add the contraposition axiom to several important extensions of N, show that certain extensions of N are canonical, and also revisit the method of filtration.