Definition:Extraordinary Set
(Redirected from Definition:Abnormal Set)
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Definition
Let $S$ be a set.
Then $S$ is an extraordinary set if and only if:
- $S \in S$
That is, $S$ is an element of itself.
Also known as
Some sources refer to such a set as an abnormal set.
Also see
Sources
- 1963: George F. Simmons: Introduction to Topology and Modern Analysis ... (previous) ... (next): $\S 1$: Sets and Set Inclusion
- 2010: Raymond M. Smullyan and Melvin Fitting: Set Theory and the Continuum Problem (revised ed.) ... (previous) ... (next): Chapter $1$: General Background: $\S 8$ Russell's paradox