Soft multisets and a decision-making method in soft multisets

This thesis provides the soft sets, soft matrices, and some of their basic properties. It then presents fuzzy sets, fuzzy soft sets, and fuzzy soft matrices. The third section examines multisets and some of their basic properties. The fourth section studies soft multisets being a hybrid version of soft sets and multisets. The fifth section proposes two soft multi decision-making methods and applies them to a decision-making problem on side effects that emerged after the COVID-19 vaccine. Finally, the present thesis discusses the proposed approach herein and the need for further research.