
The paper solves in the negative the problem of the existence of independent axiomatizations for modal and intermediate propositional logics (formulated by A. Tsytkin in 1986). The main idea is to use the following necessary condition: if a logic \(L\) is independently axiomatizable then every interval of logics \([L_1, L]\) with \(L_1\) finitely axiomatizable, contains an immediate predecessor of \(L\). A related property studied by \textit{W. J. Blok} [Algebra Univers. 11, 285-294 (1980; Zbl 0457.08003)] is the strong coatomicity of a lattice of logics; it is the same as above, but \(L_1\) can be arbitrary. Blok proved that the lattice of normal modal logics is not strongly coatomic, but, as the authors observe, it seems unlikely that in his counterexample \(L_1\) is finitely axiomatizable. The reviewed paper disproves independent axiomatizability for modal logics above K4 and for intermediate logics via differentiated (general) Kripke frames. For the intermediate case ``Fine's ladder'' is used. The same construction yields also counterexamples above Grz and in the intervals [S4,S5] and [S4,Grz].
differentiated frame, independent axiomatizations, Kripke frames, intermediate logics, strongly coatomic lattice, Modal logic (including the logic of norms), modal logics, Intermediate logics, canonical formulas
differentiated frame, independent axiomatizations, Kripke frames, intermediate logics, strongly coatomic lattice, Modal logic (including the logic of norms), modal logics, Intermediate logics, canonical formulas
| selected citations These citations are derived from selected sources. This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | 10 | |
| popularity This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network. | Average | |
| influence This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically). | Top 10% | |
| impulse This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network. | Average |
