Concept · Foundations

Element (Member)

An object belonging to a set; if x is an element of the set A, we write x ∈ A, and if it is not, we write x ∉ A.

Why it matters

Membership is the one primitive relation of set theory, and every other notion in the unit is defined in terms of it.

Where this shows up

Units and lessons using this concept

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Units (1)

Lessons (1)