📜 Theorem, law or theory

Knaster–Tarski theorem

Teorema de Knaster-Tarski

Date
1928/1955 · confidence low
Place
Berkeley, California, United States
Credited to
Bronisław Knaster and Alfred Tarski
Field
Knowledge & symbols

What was discovered

The Knaster–Tarski theorem, in lattice theory, states that if (L, ≤) is a complete lattice and f: L → L is an order-preserving function, then the set of fixed points of f in L also forms a complete lattice. Bronisław Knaster and Alfred Tarski proved a special case in 1928, and Tarski generalized it in 1955.

What it led to

  • Standard tool for proving the existence of fixed points in theoretical computer science
  • Basis of the denotational semantics of recursion in programming languages
  • Use in game theory and economics (existence of equilibria)
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