Plectis
Erdős problem #269

Three-prime running least common multiples

For a finite set of at least two primes, is the sum of reciprocals of the running least common multiples of the smooth numbers irrational? This library treats the three-prime case.

Open 7 Lean modules 2 main results Source directory

What is checked in Lean

  • That for three pairwise distinct primes the least common multiple of the smooth prefix equals the product of the three maximal pure prime powers below the cutoff.
  • That equal logarithmic coordinates give an equal prefix least common multiple, so the running value is constant on logarithmic cells.
  • That advancing exactly one logarithmic coordinate multiplies the running value by the corresponding prime.
  • That the positive power channels of distinct primes are disjoint, so the first powers in three channels give an exact jump count.
  • That a finite smooth lattice sum groups exactly by running height, with the height fibre cardinality as coefficient.
  • A quadratic bound on the cardinality of the actual filtered exponent shell.
  • That each dyadic block contains at most one internal pure power from each non-dyadic channel, so the compressed {2,3,5} block radix belongs to the exact alphabet {2,6,10,30} and in particular lies between 2 and 30.
  • That the smallest {2,3,5} kernel rectangle has determinant exactly -1/15, so its two-by-two matrix has rank two over the rationals and no rank-one separation exists.
  • The canonical least-positive-residue interval and congruence facts, including the zero-residue representative.
  • The exact local-window identity for an integral carry.
  • A denominator-dependent CofinalLocalWindowEscape proposition and the full theorem that it rules out every positive reduced integral carry satisfying the matching bound.
  • A bounded-radix dichotomy: under a bounded positive digit alphabet, a nonzero scaled tail must be separated from the integers cofinally.
  • Exact three-channel block-nullity as a coboundary condition, and extinction of a bounded carry lift under two independent anchors.
  • The exact residue-digit plus coboundary form of an integral carry, together with a function-faithful observer criterion and a finite realised-span consequence.

Main results

Statements and boundaries are copied from the corpus record. Registry status: not_registered; the claim registry does not carry these declarations and kernel checking them does not promote them into reviewed public claims

What is not checked

  • Irrationality or transcendence in any three-prime case.
  • The derivation of the actual bounded positive carry, including the divisibility required to cancel the absorbed smooth denominator factor, from a hypothetical rational value of the original series.
  • CofinalLocalWindowEscape for those actual words; it is an explicit hypothesis of the checked consumer, not a theorem.
  • A proof that the actual three-channel word satisfies the block-null, anchor, or factorisation hypotheses of the migrated abstract consumers.
  • The infinite limit of the jump expansion; only its finite core is checked.
  • Any unbounded denominator exclusion. The finite certificates exclude denominators below an explicit bound and no further.

Open obligations

Prove any one of these and the corresponding reduction above becomes unconditional.

  • actual_local_window_residue_escape For every positive B coprime to 30 and every starting index, produce a later actual {2,3,5} window whose least positive forcing residue exceeds the exact denominator-dependent carry bound.
  • actual_rational_carry_instantiation Identify the formal radix word with the checked four-symbol dyadic block base, formalize the exact block digit and its link to the original summand multiplicities, and derive the positive reduced carry recurrence and its bound from a hypothetical rational value.
  • nonstationary_analytic_theorem Prove a genuinely higher-dimensional analytic theorem for the phase cocycle or the associated contraction.
  • unbounded_height_certificate Replace one finite denominator exclusion by a family whose exclusion bound tends to infinity.

Lean modules

Comparator review

The Comparator replays selected exact interfaces against a pinned toolchain. It never widens what Lean proved.

Replayed by the Comparator

Statement and type parity replayed against the pinned toolchain.

  • Exact running-LCM product, logarithmic-cell constancy, coordinate jump ratios, and jump count.

    Cell structure alone does not prove irrationality.

    three_prime_lcm_cells · targeted_running_lcm_identity

  • The 2,3,5 kernel is not rank one and its smallest displayed minor equals -1/15.

    Failure of rank one does not itself imply irrationality.

    rank_two_kernel_no_go · targeted

Represented indirectly

Covered through a neighbouring selected interface, not replayed one-to-one.

  • Finite height-fibre normal form and a quadratic smooth-shell multiplicity bound.

    The fibre bounds do not provide the missing divisibility bridge.

    height_fibre_and_shell · represented_by_three_prime_structure_target

  • The exact dyadic block alphabet is 2, 6, 10, and 30.

    The finite alphabet does not supply the needed carry escape.

    dyadic_block_alphabet · represented_by_three_prime_structure_target

Outside the Comparator selection

Stated in the corpus; not part of the replayed interface set.

  • Both two-prime running-lcm series are proved transcendental by an authored deduction from an external theorem.

    Comparator cannot certify the external analytic input.

    two_prime_transcendence · not_applicable_not_a_lean_declaration

  • Cofinal local-window residue escape would rule out bounded positive carries after an unproved rationality-to-carry bridge.

    The producer and actual-series identification are missing.

    conditional_carry_escape · not_selected_unproved_bridge_and_deep_predicates

  • A local-window checker searches 106666 denominator and start pairs and records small certificates.

    Finite search is not a cofinal statement.

    three_prime_finite_search · not_applicable_not_a_lean_theorem

The paper

Problem note 23 pp

The Three-Prime Running Least Common Multiple

For every pair of distinct primes, both the de-duplicated sum and Erdős's repeated running-lcm sum are proved transcendental by a paper argument using Bugeaud–Laurent; that deduction is not Lean-formalised, and Steve Fan published the same two-prime reduction first, on 26 June 2026, so no priority is claimed for it. For three primes, Lean gives the exact running-lcm product, logarithmic cells, shell bounds, the four-value radix at 2, 3, 5, and a rank-two nonseparability witness. The remaining criterion is conditional: its rationality-to-carry divisibility bridge and cofinal residue escape are unproved, while the reported scan is finite. Erdős #269 remains open from three primes onward.