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exactly two digits are their own mirror

lean
theorem exactly_two_digits_are_their_own_mirror :
  (digits.filter (fun d => tv d == d)) = [0, 5]

Accepted by the Lean 4 kernel. The proof rests on no axioms at all.

Proven means three things together: the kernel accepted the file, the proof contains no sorry, and #print axioms reports a dependency set within {propext, Quot.sound}. The dependency set above is the evidence, recorded per theorem rather than summarised.

sourcelean/DigitSpace.lean:188
archivedoi:10.5281/zenodo.22178675 — the concept DOI, resolving to the newest release
corpusevery statement · the ledger
reproducegit clone https://github.com/ceccec/zeropoint-node && npm run lean:check

Speaks of the same objects as

What this does not establish

A theorem is a statement the kernel accepted. It says nothing about whether the surrounding package is useful, whether the idea is novel, or whether anything physical follows. Novelty is a universal negative no finite search decides; a dated deposit establishes priority, which is the defensible claim.