Definition:Disjoint Union (Set Theory)/Disjoint Sets

Definition

Let $A$ and $B$ be disjoint sets, that is:

$A \cap B = \O$

Then the disjoint union of $A$ and $B$ can be defined as:

$A \sqcup B := A \cup B$

where $A \cup B$ is the (usual) set union of $A$ and $B$.

Sources

• 1978: Lynn Arthur Steen and J. Arthur Seebach, Jr.: Counterexamples in Topology (2nd ed.) ... (previous) ... (next): Part $\text I$: Basic Definitions: Section $1$: General Introduction: Functions
• 1996: H. Jerome Keisler and Joel Robbin: Mathematical Logic and Computability ... (previous) ... (next): Appendix $\text A$: Sets and Functions: $\text{A}.2$: Boolean Operations