We present tableau systems and sequent calculi for the intuitionistic analogues and IS5 of the normal classical modal logics. We provide soundness and completeness theorems with respect to the models of intuitionistic logic enriched by a modal accessibility relation, as proposed by G. We also investigate the relationship of these logics with some other intuitionistic modal logics proposed in th...

Another way to do this is to use individual elements. Take an element from {2, 6} and an element from {3, 7} and add them. Find the coset that contains the sum. That coset is the sum of the cosets. For example, if I use 6 from {2, 6} and 3 from {3, 7}, I get 6 + 3 = 1, which is in {1, 5}. Therefore, {2, 6}+ {3, 7} = {1, 5}. What happens if you choose different elements? Take 2 from {2, 6} and 7...

We study some properties of interval-valued fuzzy normal subgroups of a group. In particular, we obtain two characterizations of interval-valued fuzzy normal subgroups. Moreover, we introduce the concept of an interval-valued fuzzy coset and obtain several results which are analogous of some basic theorems of group theory.