Definition:Symmetric Difference

Illustration by Venn Diagram
The red area in the following Venn diagram illustrates $S * T$:


 * VennDiagramSymmetricDifference.png

Also known as

 * Disjoint Union
 * Boolean Sum

Notation
There is no standard symbol for symmetric difference. The one used here: $*$ has been chosen somewhat arbitrarily; it's the one found by the author in the nearest work to hand.

The following are often found for $S * T$:


 * $S \oplus T$
 * $S + T$
 * $S \mathop \triangle T$

According to :


 * $S \mathop \Theta T$
 * $S \mathop \nabla T$

are also variants for denoting this concept.

Also see

 * Equivalence of Definitions of Symmetric Difference