# MathML mo Element Operators by Stephen Bucaro

The mo element is possibly the most important part of MathML. This is because it specifies mathematical operations and mathematics is essentially about operations. You'll need to use character codes to specify some operations because there are no, for example, ≠ keys on the computer keyboard.

$a\ne b$
$<mi>a</mi> <mo>≠</mo> <mi>b</mi>$


The example above uses an inequality operator to state that a does not equal b. Shown below are the character codes for some other inequality operators.

 Symbol Meaning Character Code ≠ Not equal ≠ ≈ Approximately equal ≈ < Less than < ≤ Less than or equal ≤ > Greater than > ≥ Greater than or equal ≥ ± Plus or minus ±

Shown below are the character codes for some trigonometry symbols.

 Symbol Meaning Character Code ° Degree ° ∠ Angle ∠ ⦜ Right angle ⦜

Shown below are the character codes for some Greek symbols.

 Symbol Meaning Character Code α Alpha α β Beta β γ Gamma γ δ Delta δ π Pi π ω Omega; ω

$\underset{-1}{\overset{+1}{\int }}\frac{dx}{x}$
$<mrow> <munderover> <mo>&#8747;</mo> <mn>-1</mn> <mn>+1</mn> </munderover> <mfrac> <mrow> <mi>d</mi> <mi>x</mi> </mrow> <mi>x</mi> </mfrac> </mrow>$


The example above shows a calculus expression using an integral operator. Shown below are the character codes for some other calculus operators.

 Symbol Meaning Character Code ∑ Summation ∑ Δ Increment Δ ∫ Integration ∫ ∫ Infinite ∫