Confinement certificates for powers of rational numbers modulo one

Ralf Stephan

For positive ξ, the fractional parts of ξ(3/2)ⁿ cannot all lie in [1/6,13/24), a specific single interval of length 3/8. A finite block certificate and a general soundness argument establish this exclusion.

Sources for this record

What was already known

Dubickas ruled out confinement in closed intervals of length 1/3 at base 3/2. Earlier results also treated other particular windows and unions.

AI involvement AI-led

Ralf Stephan chose the targets and reviewed statements. He credits Claude Fable 5 with the mathematics and Claude Opus 4.8 with the Lean formalization.

The source explicitly credits Claude Fable 5 with the mathematical discovery and Claude Opus 4.8 with the formal proof under Stephan's direction.

Importance Notable

The certified single interval is longer than the classical 1/3 threshold.

Limitations

This is a result for one positioned window, not every interval of length 3/8; it does not solve Mahler’s length-1/2 problem.

Technical verification Formal (Lean 4 kernel exact integer certificate and Comparator)

The 3/8 window is a named compared statement. The cited source reports Comparator checking its statement and Lean kernel evaluation of the exact integer certificate from raw data, with standard axioms only. This batch did not reproduce the check.

Formal checking

statement comparison and kernel reduction of Cert.ok on exact integer certificate data

Checker
Palomar Comparator and Lean kernel
Scope
Z32.ZSet_three_two_sixth_3_8, emptiness of the stated 3/2 confinement set
Basis
Reported by the linked checker
Evidence source

Checking a formal statement does not establish that it matches the original problem.

Human understanding Few

Stephan checked statements, but the source assigns mathematical discovery and paper drafting to AI and records no named human explanation of the central certificate construction. Few is the missing-evidence default, not a claim that Stephan cannot understand it.

Correction and publication history