Syracuse descent within ten steps on 155 progressions modulo
Provedsyracuse_descent_progressions_seven_mod32_mod65536Let denote the Syracuse map on the natural numbers,
that is, the odd part of , where is the -adic valuation, and let denote its -fold iterate, with . Let , and be the three finite sets of residues listed below. For every natural number satisfying
there is a natural number with
The residue sets are:
- consists of the following residues modulo : 679, 1191, 2663, 3687, 4199, 4455, 5191, 5607, 5959, 6215, 6375, 6631, 6983, 7079, 7399, 7495, 7847, 7911, 8103.
- consists of the following residues modulo : 839, 1095, 2119, 2279, 2727, 2983, 3303, 4007, 6503, 6759, 7783, 9959, 10055, 11079, 11943, 12967, 14439, 16743, 16871, 17735, 17767, 19623, 20199, 21223, 23399, 24647, 24679, 25703, 25831, 26087, 26535, 27111, 27975, 28999, 29863, 30311, 30887.
- consists of the following residues modulo : 359, 1351, 2407, 2791, 2887, 3239, 3815, 4775, 5863, 6247, 7015, 8263, 8551, 9319, 9543, 10151, 10727, 11431, 12007, 12615, 12775, 13671, 13927, 14503, 15207, 16455, 17127, 17223, 17479, 17511, 18343, 18919, 19111, 19367, 19687, 20807, 21735, 22119, 22695, 22887, 23143, 25415, 25671, 26343, 26439, 27303, 27559, 27879, 28327, 31079, 31335, 33255, 34151, 34535, 34631, 36519, 37607, 37735, 40039, 41063, 41447, 42215, 42343, 42471, 43111, 43335, 44359, 45223, 45799, 46247, 46407, 48295, 49255, 50407, 50663, 51271, 51431, 52071, 52551, 53159, 53319, 54375, 54439, 55207, 56935, 57671, 58983, 59463, 59559, 59623, 60231, 61351, 62119, 62279, 63335, 63591, 64167, 64871, 65127.
Each residue determines an infinite arithmetic progression, so the statement covers every member of progressions, not a finite range of inputs.
These progressions refine the residual classes modulo of the open theorem syracuse_descent_residual_mod4096: every one of the progressions lies inside one of those classes, and together they cover of the residue classes modulo that lie over them. Combined with the complementary residual statement, this splits that open theorem into a proved part with a uniform ten-step bound and a smaller open part.
Formalization Note. The Syracuse map is the existing platform definition syracuseStep, and is the Mathlib iterate syracuseStep^[t]. The three residue sets are written as explicit Finset ℕ literals, and the uniform bound is part of the conclusion.
import Definitions.Def_syracuseStep import Mathlib.Logic.Function.Iterate import Mathlib.Data.Finset.Insert
theorem syracuse_descent_progressions_seven_mod32_mod65536 (n : ℕ)
(h : n % 8192 ∈ ({679, 1191, 2663, 3687, 4199, 4455, 5191, 5607, 5959, 6215,
6375, 6631, 6983, 7079, 7399, 7495, 7847, 7911, 8103} : Finset ℕ) ∨
n % 32768 ∈ ({839, 1095, 2119, 2279, 2727, 2983, 3303, 4007, 6503, 6759,
7783, 9959, 10055, 11079, 11943, 12967, 14439, 16743, 16871, 17735,
17767, 19623, 20199, 21223, 23399, 24647, 24679, 25703, 25831, 26087,
26535, 27111, 27975, 28999, 29863, 30311, 30887} : Finset ℕ) ∨
n % 65536 ∈ ({359, 1351, 2407, 2791, 2887, 3239, 3815, 4775, 5863, 6247,
7015, 8263, 8551, 9319, 9543, 10151, 10727, 11431, 12007, 12615,
12775, 13671, 13927, 14503, 15207, 16455, 17127, 17223, 17479, 17511,
18343, 18919, 19111, 19367, 19687, 20807, 21735, 22119, 22695, 22887,
23143, 25415, 25671, 26343, 26439, 27303, 27559, 27879, 28327, 31079,
31335, 33255, 34151, 34535, 34631, 36519, 37607, 37735, 40039, 41063,
41447, 42215, 42343, 42471, 43111, 43335, 44359, 45223, 45799, 46247,
46407, 48295, 49255, 50407, 50663, 51271, 51431, 52071, 52551, 53159,
53319, 54375, 54439, 55207, 56935, 57671, 58983, 59463, 59559, 59623,
60231, 61351, 62119, 62279, 63335, 63591, 64167, 64871, 65127} : Finset ℕ)) :
∃ t : ℕ, t ≤ 10 ∧ syracuseStep^[t] n < n := by sorry