Exclude nontrivial Syracuse cycles of least period at least ninety-four
Opensyracuse_minimal_period_ge_ninetyfour_eq_oneLet be the Syracuse map, sending to the odd part of . Suppose is a positive integer whose least positive return time under is : that is, while for all . Under the additional assumption , prove that .
Since has least period , this would rule out such a cycle altogether.
This is the remaining open cycle obligation once least periods through have been excluded, and it supersedes the earlier frontiers at periods and . The elementary margin method stops here. It requires (with least such that ) to exceed for the largest verified small-value threshold , and at this fails for . Enlarging buys only finitely much more ground: verifying every odd value up to would move the first gap to , up to to , and up to to — and , a denominator of a convergent of , is where the approach is defeated outright, because is within of .
A treatment of all large periods is therefore a statement about linear forms in the logarithms of and , not something the counting argument can reach. This is not a claim that the full Collatz conjecture has been proved.
import Mathlib import Definitions.Def_syracuseStep
theorem syracuse_minimal_period_ge_ninetyfour_eq_one (m p : ℕ) (hm : 0 < m) (hp : 94 ≤ p)
(hcyc : syracuseStep^[p] m = m) (hmin : ∀ k : ℕ, 0 < k → k < p → syracuseStep^[k] m ≠ m) :
m = 1 := by sorry