# What is µ A below ~ x in the Fuzzy Logic

I am reading the book "Fuzzy Logic with Engineering" written by Timothy J. Ross and there is a phrase in the book at page 90, he mentions about the "Features of the Membership Function". He says:

The support of a membership function for some fuzzy set A under ~ is defined as that region of the universe that is characterized by nonzero membership in the set A under ~. That is, the support comprises those elements x of the universe such that μ A under ~ (x)>0.

He denotes it as a graphical representation:

what is μ A under ~ (x) in this context? Thanks in advance.

Edit Post The μ A under ~ (x) in this context is membership function. https://www.tutorialspoint.com/fuzzy_logic/fuzzy_logic_membership_function.htm

• The picture is pretty clear: the support of $A$ is the set of $x$ such that $\mu(x) > 0$. The core is the set of $x$ such that $\mu(x) = 1$, and the boundary is the set of $x$ such that $0 < \mu(x) < 1$. – Yuval Filmus Apr 5 '20 at 13:59
• What is the definition of μ? – tahasozgen Apr 5 '20 at 14:16
• I have no idea, since I don't have access to the book. However, I am certain that $\mu$ is defined in the book, moreover in the first 90 pages. – Yuval Filmus Apr 5 '20 at 14:17