Unicode: 222E. Alias: Esc cint Esc. Compound operator. ∮ f x is by default interpreted as ContourIntegral[f,x].
Unicode: 2233. Alias: Esc cccint Esc. Compound operator. ∳ f x is by default interpreted as CounterClockwiseContourIntegral[f,x].
\[Cup]
(Mathematica Character Name) Unicode: 2323. Infix operator. x ⌣ y is by default interpreted as Cup[x,y]. Used in pure mathematics to mean cup product.
Unicode: 22C4. Alias: Esc dia Esc. Infix operator. x ⋄ y is by default interpreted as Diamond[x,y].
Unicode: F76E. Alias: Esc dlsep Esc. Spacing character. Used to invisibly denote a place where automatic line breaking should be allowed.
Unicode: 222F. Compound operator. ∯ f s is by default interpreted as ContourIntegral[f,s]. Used to indicate integrals over closed surfaces.
Unicode: 21D3. Infix arrow operator. x ⇓ y is by default interpreted as DoubleDownArrow[x,y]. Extensible character.
Unicode: 27F8. Alias: Esc <== Esc. Infix arrow operator. x ⟸ y is by default interpreted as DoubleLongLeftArrow[x,y].
Unicode: 27FA. Alias: Esc <==> Esc. Infix arrow operator. x ⟺ y is by default interpreted as DoubleLongLeftRightArrow[x,y]. Not the same as \[Equivalent].
Unicode: 27F9. Alias: Esc ==> Esc. Infix arrow operator. x ⟹ y is by default interpreted as DoubleLongRightArrow[x,y].