Definition of de Morgan's laws in English:

de Morgan's laws

  • Two laws in Boolean algebra and set theory which state that AND and OR, or union and intersection, are dual. They are used to simplify the design of electronic circuits.

    • ‘de Morgan's laws are named after the Indian-born British mathematician and logician Augustus De Morgan (1806-1871).’
    • ‘In set theory, de Morgan's laws relate the three basic set operations to each other; the union, the intersection, and the complement.’
    • ‘In logic, De Morgan's laws (or De Morgan's theorem), named for nineteenth century logician and mathematician Augustus De Morgan, are two powerful rules of Boolean algebra and set theory.’
    • ‘This completes the proof of the first of De Morgan's laws; the second is obtained by similar reasoning.’


Early 20th century: named after Augustus De Morgan (1806–71), English mathematician, but already known (by logicians) as principles in the Middle Ages.


de Morgan's laws

/də ˈmôrɡənz ˌlôz/