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Device: the dyadic corona pairing

Agent 3 — 2-adic / real hybrid geometry.

Not a residue-class list. Not a translate clock v₂(n+5) or v₂(11n+19). Not a frozen window of length L. The scale is a function of real size.

No Collatz claim is made. Heavy coronas expand (27, 31, Mersenne prefixes). The pinch below kills only the strongly light ones.


Exact definition

At every positive integer there are two simultaneous objects: the archimedean size |n| and the 2-adic point n ∈ ℤ₂. Pair them at a dynamic scale

κ(n)  :=  ⌊log₂ n⌋

selected by the real magnitude, not prescribed in advance. The hybrid state is

S(n)  =  ( n ,  n mod 2^{κ(n)} )  ∈  ℕ  ×  ℤ/2^{κ(n)}ℤ.

Write mantissa(n) := n mod 2^{κ(n)}. Because n lies in the dyadic annulus [2^{κ(n)}, 2^{κ(n)+1}), the high part at this scale is identically the unit:

n  =  2^{κ(n)}  +  mantissa(n),     highPart_{κ(n)}(n)  =  1.

That is the geometry: real size is the 2-adic precision, and the remaining 2-adic coordinate is a proper residue at that precision — a different modulus for every dyadic annulus. A list of classes modulo a frozen 2^L cannot express this, because L here moves with |n|.

A companion scale, still a function of |n|, is the midscale pinch window

π(n)  :=  ⌊κ(n)/2⌋.

The strongly light predicate at a window of length k is

StronglyLight(n, k)  :⇔  2 · 3^{oddCount(n,k)}  ≤  2^k.

The factor 2 is not a fudge: it is the exact matching of affineC < 2^k·3^a against the corona lower bound n ≥ 2^k.

Lean: Collatz.Strategy.DeviceHybrid.


The two arrows

The accelerated map T is n/2 on evens and (3n+1)/2 on odds.

1. Real expansion forces 2-adic localisation. After κ(n) steps the corona identity is

T^{κ(n)}(n)  =  3^a  +  T^{κ(n)}(mantissa(n)),

a = oddCount(n, κ(n)), which is a function of the mantissa alone (stronglyLight_of_mantissa). Non-drop T^{κ(n)}(n) ≥ n rewrites as

2^{κ(n)} + mantissa(n)  ≤  3^a + T^{κ(n)}(mantissa(n))

(expansion_localizes). A real lower bound has become a lower bound on the odd-density of a 2-adic window whose length was chosen by |n|.

2. That localisation forces future real contraction — when it is strong. If the window is strongly light, the same identity yields

T^{κ(n)}(n)  <  n

(light_corona_drops). Proof: affine_exact plus affineC_lt give C < 2^κ·3^a, strong lightness gives 3^a ≤ 2^κ − 3^a, and the corona supplies n ≥ 2^κ, so C < n·(2^κ − 3^a).

This is the even branch x ↦ x/2 being consumed. It is not a valuation of a fixed translate, and it is not a statement about a frozen modulus.

The midscale form light_pinch_drops is the same pinch at π(n), where the high part is at least 2^{π(n)} rather than 1.


What this knows about a single orbit that the parity word does not

Terras: a word of length k is a residue class modulo 2^k, realised by some r < 2^k. On that fibre the magnitude is free (ScaleFibre.fibre_affine: rank one, E(w)/n).

At the corona the fibre is not free. The window length is κ(n), so the Terras representative would have to satisfy r < 2^{κ(n)} ≤ n. The integer under study is the unique lift of its mantissa into the next dyadic annulus. You cannot vary the starting integer independently of the word length: they are locked by |n|.

Three concrete data the free word does not carry:

  1. Which modulus is being read. κ(n) is not a letter of the word.
  2. The unit high part. highPart_{κ(n)}(n) = 1 is an archimedean fact. At a frozen L the high part is the free coordinate HighPart already analysed; here it is frozen to 1 by the choice of scale.
  3. The jump of scales along one orbit. After κ(n) steps the landing 3^a + T^κ(mantissa) has a new corona scale κ(T^{κ(n)}(n)). The hybrid state maps coronas to coronas. A single parity word of unspecified length has no such jump.

WindowCollapse says consecutive frozen windows are one longer word. That collapse assumes the window length is chosen independently of magnitude. It does not apply to κ(n).


What this knows about 3n+1 that expStep does not

expStep agrees with T on odds and replaces the even branch by 3x/2. Its affine law saturates a = j at every window (ScaleRecord.expOrbit_affine).

  • Saturation is incompatible with strong lightness at a positive scale (saturated_not_strongly_light). expStep never meets the hypothesis of light_corona_drops.
  • At the same dynamic window, expStep grows: for every n ≥ 2, n < expOrbit(κ(n), n) (expStep_fails_corona_drop). Checked on all n ∈ [2, 200]; the proof is expOrbit_ge plus κ(n) ≥ 1.

So the pinch is not a theorem of affine law + heaviness + positivity. It uses the contracting even branch that expStep deletes. A divergence-half mechanism that expStep satisfies cannot be this pinch.


Tests

Collatz (d = 1)

Strongly light coronas in n = 2..200: 109 of them, 0 drop failures. Examples: 2, 4, 8, 10, 12, 13, 16, 20. These are numbers whose low κ(n) bits are sparse in odd steps.

Heavy coronas that grow, as they must: 3, 7, 9, 11, 14, 15, 23, 25, 27, 31. The Mersenne prefix 31 = 2^5−1 is the extreme: a = κ = 4, saturation, no pinch. This is the open side of the device, not a counterexample to the theorem.

3x+5

The small cycle {5, 10}: at the never-dropper 5, the corona is not strongly light (k=2, a=1, 2·3=6 ≰ 4), and T^2(5)=5 does not drop. At 10 the corona is light and drops to 5 — toward the cycle minimum, not off the cycle.

The length-27 cycle through 187: the unique never-dropper on the cycle is the minimum 187 itself, whose corona is heavy (k=7, a=6, T^7(187)=1091>187). Other cycle points can be strongly light and drop toward 187. That is allowed: the pinch is a statement about one window of one value, not a Lyapunov function on a cycle.

Empirically, every strongly light corona for 3x+5 on n = 2..4000 drops (2731 lights, 0 failures). The proved d=1 pinch does not automatically transfer: C scales with d, so the matching constant 2 may need to become 2d. The computation says the actual accumulator is smaller than the crude bound, and the same constant still pinches in this range. The Lean theorem is stated only for d=1.

3x+7

Cycle {5, 11, 20, 10}. The never-dropper is 5: corona heavy (k=2, a=2), T^2(5)=20>5. The point 11 is strongly light and drops to 5.

Empirically the same as 3x+5: 2733 strongly light coronas on n=2..4000, 0 drop failures. Same caveat: Lean proves the pinch for 3x+1 only.

expStep

Fails both halves of the device, as required. See above.


First theorems (LEAN_PROVED, no sorry)

theorem statement
corona_highPart highPart(κ(n), n) = 1
corona_orbit T^{κ(n)}(n) = 3^a + T^{κ(n)}(mantissa(n))
expansion_localizes non-drop through the corona ⇒ 2^κ + m ≤ 3^a + T^κ(m)
stronglyLight_of_mantissa lightness is a mantissa property; the scale is not
light_window_drops n ≥ 2^k and strongly light ⇒ T^k(n) < n
light_corona_drops that pinch at k = κ(n)
light_pinch_drops that pinch at k = π(n)
expStep_fails_corona_drop n < expOrbit(κ(n), n) for n ≥ 2
saturated_not_strongly_light a = k > 0 forbids strong lightness

corona_orbit is Density.accOrbit_two_pow_add evaluated at the unique scale where the high part is 1. The new content is the choice of that scale from |n|, the localisation arrow, and the pinch.


Decisive lemma (OPEN)

The pinch closes the strongly light coronas. A hypothetical never-dropper is therefore confined to heavy coronas at every orbit point:

∀ x ≥ n in the orbit of a never-dropper,  ¬ StronglyLight(x, κ(x)).

Equivalently, the mantissa of every such x has odd-density high enough that 2 · 3^{a(x)} > 2^{κ(x)}.

Decisive lemma. An infinite sequence of heavy coronas, each landing at y = 3^{a} + T^{κ}(mantissa) with y ≥ x and κ(y) ≥ κ(x), cannot continue indefinitely in the positive integers.

The intended mechanism: a heavy corona expands, so the next hybrid state is a 2-adic perturbation of a power of three (the landing sits at distance < 2·3^a from 3^a by HighPart.offset_lt). The binary digits of 3^a are not a Mersenne block. If that perturbation is forced into a strongly light mantissa at the next corona, the pinch fires and the orbit drops, contradicting never-drop. If the perturbation stays heavy forever, the 2-adic itinerary of the mantissas is a path in a proper closed subset of ℤ₂ whose real sizes are unbounded — and that subset should be shown empty, or shown to contain only the 2-adic point -1, which is not a positive integer.

This lemma is not proved. It is not Collatz. It is the remaining arrow "heavy localisation forces a later light corona". The first arrow and the light half of the second arrow are proved.

What would finish an excursion drop: show that a single heavy corona of an odd start n > 1 produces, within a bounded number of subsequent coronas, a strongly light one whose pinch lands below n. That statement, if true, is stronger than "some numbers drop" and weaker than Collatz; it is the natural target of this device.


Current obstruction

Heavy mantissas. The corona of 27 is heavy (κ=4, a=3) and grows to 47. The device as proved is silent there. Closing the heavy case by a translate clock is forbidden (those exist and do not rank). Closing it by freezing a longer window returns to Terras. The only remaining move this geometry has is the next corona of the landing 3^a + T^κ(m), whose scale has moved.


Why this is not a renamed ranking, accumulator, or excursion clock

  • It is not a ranking: T^{κ(n)}(n) is not claimed to drop for every n, and does not (27).
  • It is not affineC under a new name: affineC is used as a bound inside the pinch, but the object is the pair (κ(n), mantissa(n)).
  • It is not v₂(n+1) or v₂(n+5): no integer translate is formed. Odd-count of a dynamic window is a block statistic, not a single valuation.
  • It is not OctaveOrder: that file compares octave changes to odd times and proves they cannot obstruct each other. This file pairs the octave with the 2-adic residue at that octave and proves a drop on a subset of residues.
  • It is not Device 14's scale tower: that tower has frozen horizon length k and a drop window [n, 2n) in the reals. Here k is chosen from |n|, and the obstruction is 2-adic lightness at that scale.

Scorecard

field value
DEVICE Dyadic corona pairing S(n) = (n, n mod 2^{κ(n)}), κ(n)=⌊log₂ n⌋
DEFINITION Hybrid state at the unique scale where the high part is 1
NEW INFORMATION CAPTURED Window length locked to `
FIRST THEOREM light_corona_drops: strongly light corona ⇒ T^{κ(n)}(n) < n
EXPSTEP TEST Fails the drop (expStep_fails_corona_drop); never strongly light
3x+d TEST Cycle minima have heavy coronas (survive). Non-minima may pinch toward the min. Empirically light coronas still drop for d=5,7 on n<4000; Lean pinch is d=1 only
CURRENT OBSTRUCTION Heavy coronas (Mersenne-like mantissas). Next-corona mixing not proved
DECISIVE LEMMA An infinite heavy-corona itinerary cannot exist in the positive integers
LEAN STATUS DeviceHybrid.lean: pinch, localisation, and expStep failure PROVED. Decisive lemma OPEN. No sorry. No Collatz claim
MATHLIB STATUS Not used. Core Nat only