On new contrapositivisation techniques for fuzzy (co)implications and their generalizations.
Contrapositivisation, Fuzzy implication, Fuzzy coimplication, Triangular norm, Triangular conorm, Fuzzy negation, Overlap function, Grouping function, ($S$,$N$)-contrapositivisation, ($G$,$N$)-contrapositivisation, Quasi-overlap function, Quasi-grouping function, ($QO$,$QG$,$N$)-contrapositivisation, Automorphism, Aggregation function, Aggregated contrapositivisation, Bi-aggregated contrapositivisation, Interval-valued contrapositivisation, Min-Max contrapositivisation, Fuzzy logic, $N$-compatibility, Contrapositive symmetrization.
In this work, we introduce several contrapositivisation operators for fuzzy implications that generalize the medium contrapositivisation, we present a wide study of each of these operators with respect to the main properties commonly associated with fuzzy implications, we prove that the classes of these contrapositivisators are invariant by automorphisms and present some conditions for these operators to be $N$-compatible, we propose some construction methods of classes of triangular norms (quasi-overlaps), triangular conorms (quasi-groupings) and aggregation functions from these contrapositivisators; we introduce the Min-Max contrapositivisation technique for fuzzy implications and some of its generalizations; and finally, we introduce four contrapositivisation techniques for fuzzy coimplications so-called upper, lower, medium and ($S$,$N$)-contrapositivisation, we characterize the respective contrapositivisators with respect to the main properties commonly associated with fuzzy coimplications, we present sufficient conditions for the $N$-compatibility of these operators, we show that the classes of such operators are also invariant by automorphisms and we propose a construction method of triangular conorms from ($S$,$N$)-contrapositivisators of ($T$,$N$)-coimplications and fuzzy negations.