Soft sets theory and soft groups

In this thesis, fuzzy set theory, rough set theory, soft set theory, soft groups and some algebraic constructs of the soft groups are investigated. In the first section of the thesis, preliminary information is given about fuzzy set theory, rough set theory, soft set theory and soft groups. In the second section of the thesis, soft set theory is defined, and then definitions of the concepts of two soft set equation, soft set is not parameter, soft set of a complement, soft set of empty, soft set absolute, two soft set between the "and" operator, two soft set of "or" operator, two soft sets of combination and two soft sets of intersection are given, and some examples are presented about these concepts. In the third section of the thesis, fuzzy set theory is defined, and definitions of some concepts like fuzzy sub-group are given. In the fourth section of the thesis, rough set theory is defined, and some examples are presented. In the final section of the thesis, soft group is defined, and some concepts such as unit element of soft group, soft sub-group, soft group homomorphism, soft group isomorphism, soft normal sub-group, soft commutative groups, soft groups and vice versa, soft cyclic group, soft right cosets and soft groups of factors are introduced.