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The 11 pages that link to Diagonal argument, each with the reason it gives.

• SequenceRelated: Diagonal constructions use indexed lists to establish limits on enumeration.

• Halting problemRelated: The contradiction uses a program built to disagree with a proposed halting tester on itself.

• Countable setRelated: It shows that some infinite sets cannot be enumerated.

• Arzelà–Ascoli theoremRelated: The proof extracts convergence on a dense set, then equicontinuity extends it across the domain.

• Constructive proofRelated: It shows that indirect reasoning can still be constructive when the diagonal object is explicitly defined.

• Diagonal lemmaNarrower topic: The lemma is a logical fixed-point application of a broader diagonalization pattern.

• Undecidable problemRelated: Diagonalization underlies classic proofs that some decision problems cannot be decided.

• Ramsey's theoremRelated: Nested choices and a diagonal selection extract a set satisfying all finite stages.

• Prokhorov's theoremRelated: Subsequence extraction is a standard step in proving compactness results for measures.

• Montel's theoremRelated: Exhausting the domain by compact sets lets one subsequence converge on every compact.

• Turing's proofRelated: Turing adapts diagonalization to make a machine behave contrary to a supposed universal halting decider.