In this thesis, a generalization of the classical Rough set theory [81] is developed considering the so-called sequences of orthopairs that we define in [16] as special sequences of rough sets.Mainly, our aim is to introduce some operations between sequences of orthopairs, and to discover how to generate them starting from the operations concerning standard rough sets (defined in [29]). Also, we prove several representation theorems representing the class of finite centered Kleene algebras with the interpolation property [28], and some classes of finite residuated lattices (more precisely, we consider Nelson algebras [86], Nelson lattices [21], IUML-algebras [69] and Kleene lattice with implication [24]) as sequences of orthopairs. I am deeply thankful to my family: my parents, my sister Rosa, my brother Angelo and his girlfriend Roberta, for their unconditional love and spiritual support in all my life. v vii "I magination is the Discovering Faculty, pre-eminently. It is that which penetrates into the unseen worlds around us, the worlds of Science. It is that which feels & discovers what is, the real which we see not, which exists not for our senses. Those who have learned to walk on the threshold of the unknown worlds, by means of what are commonly termed par excellence the exact sciences, may then with the fair white wings of Imagination hope to soar further into the unexplored amidst which we live.