# Definition:Symmetric Difference/Definition 4

## Definition

The symmetric difference between two sets $S$ and $T$ is written $S * T$ and is defined as:

$S * T = \paren {S \cup T}\cap \paren {\overline S \cup \overline T}$

where:

$\cap$ denotes set intersection
$\cup$ denotes set union
$\overline S$ denotes the complement of $S$.

### Notation

There is no standard symbol for symmetric difference. The one used here, and in general on $\mathsf{Pr} \infty \mathsf{fWiki}$:

$S * T$

is the one used in 1971: Allan Clark: Elements of Abstract Algebra.

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

$S \oplus T$
$S + T$
$S \mathop \triangle T$ or $S \mathop \Delta T$

According to 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics: Entry: symmetric difference:

$S \mathop \Theta T$
$S \mathop \triangledown T$

are also variants for denoting this concept.

### Illustration by Venn Diagram

The symmetric difference $S * T$ of the two sets $S$ and $T$ is illustrated in the following Venn diagram by the red area: ## Also see

• Results about symmetric difference can be found here.