Identifier
F:godel-first-incompleteness
Proof route
Not assigned
External status
proved
Axiom footprint
Empty

Recorded description

Every consistent, effectively axiomatised formal system that interprets enough elementary arithmetic contains an arithmetical sentence that the system neither proves nor refutes.

Formal statement
; NOT EXPRESSIBLE. The proposition quantifies over formal systems and over derivations within them. Nothing in the axeyum term language denotes a formula, a proof, or a provability predicate, so there is no assertion whose negation being unsat would establish it. Recorded verbatim rather than approximated, because an approximation would be checkable and would not be this statement.

Dependencies

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0 direct dependencies 0 direct dependents

Evidence

Provenance

{
  "date": "2026-08-14",
  "established_by": "not established in this ledger",
  "source": "authored from the S:logic-and-proof strand of the math-education concept graph; statement written here, not copied",
  "prior_art": [
    {
      "citation": "Godel 1931",
      "establishes": "the theorem, long settled; also formalised and machine-checked in several proof assistants (Shankar in Nqthm 1986, Paulson in Isabelle/HOL 2014)"
    }
  ]
}