If x is a fusible number and y is its successor, then the interval [x + 1, y + 1) can be divided into intervals [ℓₙ, ℓₙ₊₁), such that the fusible numbers in [ℓₙ, ℓₙ₊₁) are obtained by fusing the n + 1st successor of x with a fusible number. This formalization differs from Conjecture 7.1 in the paper in four ways: (1) it is obtained from Conjecture 7.1 by plugging in n + 1 into n, which simplifies the expressions and removes the need to assume n ≥ 1; (2) the n + 1st successor s^(n+1)(x) is replaced by the explicit value x + (2 - 1 / 2 ^ n) * m; (3) instead of defining y to be the successor of x, we assert that there is no fusible number strictly between x and y; (4) instead of using ∃ z, IsFusible z ∧ q = s^(n+1)(x) ~ z we use the value of z determined by the equality, namely z = 2 * q - 1 - s^(n+1)(x), and it is easy to see z ∈ [x + 1 - m / 2 ^ n, x + 1) as required.
Mathematical status Open: marked research open in google-deepmind/formal-conjectures at revision cd3d8db4634733a748b2380f80f77ba3e4b9dda0 (checked 2026-09-11).
Formal availability A Prop definition is supplied for the pinned Lean 4.33.1 environment and must be accepted by the deployed verifier before it is available.
Sources and provenance Upstream reference cited by formal-conjectures (checked 2026-09-11): https://arxiv.org/abs/2003.14342 Upstream reference cited by formal-conjectures (checked 2026-09-11): https://doi.org/10.46298/lmcs-18%283%3A6%292022 Formal statement provenance (Apache-2.0) (checked 2026-09-11): https://github.com/google-deepmind/formal-conjectures/blob/cd3d8db4634733a748b2380f80f77ba3e4b9dda0/FormalConjectures/Paper/FusibleNumber.lean Local target: Corpus.PaperFusibleNumber.conj_7_1 Source SHA-256: cf58c928c7d62dc1af452cfe02fc7aefd24f83e9cabf896ae10c3511e1032799 Lean v4.33.1; Mathlib 0df444a360eaa60ab8c11dca51a86af692955474; policy kernel-replay-v1. The deployed accepted environment records the actual immutable verifier image.
Research discussions are not verified proofs. A formal target specifies a precise statement; accepting a target does not prove it. Checked results apply to their exact statements and pinned environments.
If `x` is a fusible number and `y` is its successor, then the interval `[x + 1, y + 1)` can be divided into intervals `[ℓₙ, ℓₙ₊₁)`, such that the fusible numbers in `[ℓₙ, ℓₙ₊₁)` are obtained by fusing the `n + 1`st successor of `x` with a fusible number.