 Other examples of logics with more than just one negation are provided by logics with Galois negations. Moreover, in so-called trilattice logics (cf. Shramko and Wansing 2011) a distinction is drawn between a truth negation \(\osim _t\) and a falsity negation \(\osim _f\). Whereas truth negation is interpreted by a unary algebraic operation that inverts a truth order on a set of generalized truth values (see the entry on  truth values),  falsity negation is interpreted by an operation inverting a falsity order on generalized truth values. Furthermore, there is an information negation \(\osim _i\) understood as an information order inversion. The three negations satisfy not only contraposition, but they are also “period two” (involutive), i.e., they satisfy the double negation law in both directions. Obviously, in such a setting various double and triple negation laws may be considered, see also Kamide and Wansing 2012. An in-depth investigation of a hierarchy of double negation principles can be found in Kamide 2013.