---
title: "Not a member mathematical notation"
description: "Not a member is a recurring research-paper notation family. States that the object on the left does not belong to the set on the right."
canonical_url: "https://fanout.sh/labs/math-decoder/symbol/not-membership"
md_url: "https://fanout.sh/labs/math-decoder/symbol/not-membership.md"
last_updated: "2026-08-09"
access: "public"
---

# Not a member mathematical notation

Not a member is a recurring research-paper notation family. States that the object on the left does not belong to the set on the right.

## Public overview

Not a member: States that the object on the left does not belong to the set on the right. Example: Negative one is excluded from the stated natural-number set.

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