Symbols relating to discrete math

The following symbols may be used anywhere in text∶
Description
Symbol
Grafstate code
Divides
∣
|
Does not divide
∤
!|
Composition
∘
\@
Function inverse
-1
~1
Congruent
≡
≅
==
~=
Not congruent
≢
≇
!==
!~=
Also refer to the symbols for logic and for set theory .