Set Theory formula reference

De Morgan Law for Sets

Relates the complement of a union to the intersection of complements.

Open in editor
LaTeX(A\cup B)^c=A^c\cap B^c

Variables

  • A, B: subsets of a universal set
  • c: set complement

How to use this formula

Relates the complement of a union to the intersection of complements.

Important notes

  • The universal set must be understood.
  • A second law exchanges union and intersection.

Quick example

If an element is outside A∪B, it is outside both A and B.

Applicability, worked calculation, and verification

Assumptions and domain checks

  • The universal set must be understood.
  • Define the universe and the meanings of inclusion, equality, complement, and cardinality used in the expression.

Worked example

Input

Output

If an element is outside A∪B, it is outside both A and B.

Common mistakes

  • Before substituting values into De Morgan Law for Sets, map each variable to its definition and preserve every sign, exponent, subscript, and grouping mark.
  • Verify the result of De Morgan Law for Sets with a known case, inverse operation, dimensional check, or independent calculation before publishing it.

Continue the workflow

Use De Morgan Law for Sets in your own work

  1. Check the domainMatch the variables and assumptions to the problem before substituting values.
  2. Copy the exact notationPreserve grouping, signs, and exponents in (A\cup B)^c=A^c\cap B^c.
  3. Edit or convertOpen the expression in the LaTeX editor, then export it for your document or web page.

Review and verification

Last reviewed: 2026-07-23

Automated quality check: Kept noindex until the missing evidence is supplied.

Formula references

Frequently asked questions

What is the De Morgan Law for Sets used for?

Relates the complement of a union to the intersection of complements.

Can I copy this formula as LaTeX?

Yes. Copy (A\cup B)^c=A^c\cap B^c or open it in the LaTeX editor.

What should I check before using it?

Confirm that each variable, unit, domain restriction, and assumption matches the problem.

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