Diagonal argument

A diagonal argument, in mathematics, is a technique employed in proofs. The following theorems are notable examples:

• Cantor's diagonal argument (the earliest)
• Cantor's theorem
• Russell's paradox
• Curry's paradox
• Diagonal lemma
  • Gödel's first incompleteness theorem
  • Tarski's undefinability theorem
• Halting problem
• Kleene's recursion theorem
• Lawvere's fixed-point theorem (categorical generalization of all of the above)

See also

• Diagonalization (disambiguation)