Math 2.0

definition

Complement

Definition

Let UU be a universal set and let AA be a subset of UU. The complement of AA in UU is the set Ac={x∈U∣x∉A}.A^{c} = \{x \in U \mid x \notin A\}.

Remarks

Other notations are A‾\overline{A}, A′A' and U∖AU \setminus A. Example: in U=ZU = \mathbb{Z}, the complement of the set of even integers is the set of odd integers. The complement of AcA^c is AA, and A∪Ac=UA \cup A^c = U, A∩Ac=∅A \cap A^c = \varnothing. The complement of AA in UU is the set difference U∖AU \setminus A.

Explanations

L1 human

The complement is "everything else". It depends on the universe: the complement of the even numbers is the odd numbers in Z\mathbb{Z}, but not in R\mathbb{R}.

What this node needs for W2
  • edge instance_of in: one example (0 of 1)
  • edge not_instance_of in: one non-example that fails one clause (0 of 1)

The writing levels say how complete the text of a node is. They do not measure its truth.

What depends on this

235 nodes use this node, directly or through other nodes.

Sources

  1. Web https://en.wikipedia.org/wiki/Complement_(set_theory), lead section