Definition:Zero (Cardinal)

Definition

The cardinal associated with the empty set $\O$ is called zero, and is denoted $0$.

More informally, this means that zero is defined as being the number of elements in the empty set.

Also see

• Definition:Zero (Number)
• Cardinality of Empty Set

Sources

• 1975: T.S. Blyth: Set Theory and Abstract Algebra ... (previous) ... (next): $\S 8$
• 1983: François Le Lionnais and Jean Brette: Les Nombres Remarquables ... (previous) ... (next): $0$
• 1989: Ephraim J. Borowski and Jonathan M. Borwein: Dictionary of Mathematics ... (previous) ... (next): zero: 1b.