8th Ifs And Contemporary Mathematics Conference, Mersin, Turkey, 16 - 19 June 2022
In this paper we give the denitions of t-lower level set (Lt(A)) and t-upper level
set (Ut(A)) of an Intuitionistic fuzzy set.[1] A t-lower level set is dened by giving a
lower boundry on A(x) + A(x): A t-upper level set is dened by giving an upper
boundry on A(x) + A(x): If A is an Intuitionistic fuzzy set of X then Lt(A) and
Ut(A) are subsets of X.
In this paper we give some theorems by using t-lower level sets and t-upper level
sets and prove them.