📜 Theorem, law or theory

Löb's theorem

Teorema de Löb

Date
1955 · confidence high
Place
Amsterdam, North Holland, Netherlands
Credited to
Martin Löb
Field
Knowledge & symbols

What was discovered

A theorem of mathematical logic stating that, in Peano arithmetic or any formal system including it, if it is provable that "if P is provable then P is true", then P is provable; solves a problem posed by Leon Henkin about self-reference in formal systems; proved by Martin Löb.

What it led to

  • Fundamental result in provability logic (the GL system)
  • Influenced the study of self-reference and Gödel's theorems
  • Applications in type theory and program verification

Links

Sources✓ verified 2026-09-28