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2025-02-04 WR

Rearrange the digits in ⟨125034⟩ to meet the rules below.

⟨5th 4th 3rd 2nd 1st 0th⟩

✅Match
⟨ ⁵ᵗʰa     ²ⁿᵈb     ⟩, (ab)₁₀ ≤ 32
⟨⋯ 3 ⋯ 0 ⋯⟩

⛔Avoid
max ⊢1⊣ ≥ 3
⟦1,4⟧ ∋ 3,5
⟨     ³ʳᵈa ²ⁿᵈb ¹ˢᵗc   ⟩, a > b > c
Jump(2,4) ≥ 1
⟨⋯ Perm(0,1,3) ⋯⟩
5th → a, 2nd → b, a+b=4

#125034_v2.8


       ┌───┬───┬───┬───┬───┬───┐
       │5th│4th│3rd│2nd│1st│0th│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
Step 1 │ 1 │   │   │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 2 │ 1 │ 2 │   │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 3 │ 1 │ 2 │ 4 │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 4 │ 1 │ 2 │ 4 │   │ 3 │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 5 │ 1 │ 2 │ 4 │   │ 3 │ 0 │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 6 │ 1 │ 2 │ 4 │ 5 │ 3 │ 0 │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

Proof of 2025-02-04 WR
══════════════════════

(1) We first show that 1 is in corners (5th or 0th).

------------------------------

If this is not the case, then to avoid ⛔「max ⊢1⊣ ≥ 3」, we need 0,2 to be next to 1. Combining this with ⛔「Jump(2,4) ≥ 1」, we see that one of the following holds:

⟨⋯ 4210 ⋯⟩ or ⟨⋯ 0124 ⋯⟩.

Given that 1 is not in corners, we have the following possible cases:

    ┌───┬───┬───┬───┬───┬───┐
    │5th│4th│3rd│2nd│1st│0th│
    ╞═══╪═══╪═══╪═══╪═══╪═══╡
(2) │ 0 │ 1 │ 2 │ 4 │   │   │
    ├───┼───┼───┼───┼───┼───┤
(3) │   │ 0 │ 1 │ 2 │ 4 │   │
    ├───┼───┼───┼───┼───┼───┤
(4) │ 4 │ 2 │ 1 │ 0 │   │   │
    ├───┼───┼───┼───┼───┼───┤
(5) │   │   │ 0 │ 1 │ 2 │ 4 │
    ├───┼───┼───┼───┼───┼───┤
(6) │   │ 4 │ 2 │ 1 │ 0 │   │
    ├───┼───┼───┼───┼───┼───┤
(7) │   │   │ 4 │ 2 │ 1 │ 0 │
    └───┴───┴───┴───┴───┴───┘

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │   │ 5 │   │ 3 │   │
└───┴───┴───┴───┴───┴───┘

However, all of them are contradictions:

If (2)⟨0124--⟩ holds, then we cannot match ✅「⟨⋯ 3 ⋯ 0 ⋯⟩」;

If (3)⟨-0124-⟩ holds, then to match ✅「⟨⋯ 3 ⋯ 0 ⋯⟩」 we would finish by ⟨301245⟩, which matches ⛔「⟨⋯ Perm(0,1,3) ⋯⟩」 nevertheless;

If (4)⟨4210--⟩ holds, then we cannot match ✅「⟨ ⁵ᵗʰa     ²ⁿᵈb     ⟩, (ab)₁₀ ≤ 32」;

If (5)⟨--0124⟩ holds, then to match ✅「⟨ ⁵ᵗʰa     ²ⁿᵈb     ⟩, (ab)₁₀ ≤ 32」 we would finish by ⟨350124⟩, which matches ⛔「5th → a, 2nd → b, a+b=4」 however;

If (6)⟨-4210-⟩ or (7)⟨--4210⟩ hold, then we match ⛔「⟨     ³ʳᵈa ²ⁿᵈb ¹ˢᵗc   ⟩, a > b > c」.

------------------------------

We have verified (1). Now, let us consider what [5th] is. By ✅「⟨ ⁵ᵗʰa     ²ⁿᵈb     ⟩, (ab)₁₀ ≤ 32」, it is 0|1|2|3. In view of ✅「⟨⋯ 3 ⋯ 0 ⋯⟩」, it is not 0. Therefore

(8) [5th] = 1|2|3, and we show that [5th] = 1 actually.

------------------------------

If on the contrary [5th] != 1, then by (1), we have [0th] = 1:

┌───┬───┬───┬───┬───┬───┐
│5th│4th│3rd│2nd│1st│ 0▲│
╞═══╪═══╪═══╪═══╪═══╪═══╡
│   │   │   │   │   │ 1 │
└───┴───┴───┴───┴───┴───┘

and [5th] = 2|3:

     ┌───┬───┬───┬───┬───┬───┐
     │5th│4th│3rd│2nd│1st│0th│
     ╞═══╪═══╪═══╪═══╪═══╪═══╡
 (9) │ 2 │   │   │   │   │ 1 │
     ├───┼───┼───┼───┼───┼───┤
(10) │ 3 │   │   │   │   │ 1 │
     └───┴───┴───┴───┴───┴───┘

Case (9) is not possible, for combining it with ⛔「Jump(2,4) ≥ 1」 we get

┌───┬───┬───┬───┬───┬───┐
│5th│ 4▲│3rd│2nd│1st│0th│
╞═══╪═══╪═══╪═══╪═══╪═══╡
│ 2 │ 4 │   │   │   │ 1 │
└───┴───┴───┴───┴───┴───┘

and we would match ⛔「⟦1,4⟧ ∋ 3,5」. Therefore, case (10) holds:

┌───┬───┬───┬───┬───┬───┐
│5th│4th│3rd│2nd│1st│0th│
╞═══╪═══╪═══╪═══╪═══╪═══╡
│ 3 │   │   │   │   │ 1 │
└───┴───┴───┴───┴───┴───┘

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │ 2 │ 5 │ 0 │   │ 4 │
└───┴───┴───┴───┴───┴───┘

Then, to match ✅「⟨ ⁵ᵗʰa     ²ⁿᵈb     ⟩, (ab)₁₀ ≤ 32」 and avoid ⛔「max ⊢1⊣ ≥ 3」 at the same time, we need

┌───┬───┬───┬───┬───┬───┐
│5th│4th│3rd│2nd│1st│0th│
╞═══╪═══╪═══╪═══╪═══╪═══╡
│ 3 │   │   │ ▬ │ ▬ │ 1 │
└───┴───┴───┴───┴───┴───┘

where ▬ are 0 or 2. Combining this with ⛔「Jump(2,4) ≥ 1」, we get

┌───┬───┬───┬───┬───┬───┐
│5th│4th│3rd│2nd│1st│0th│
╞═══╪═══╪═══╪═══╪═══╪═══╡
│ 3 │   │ 4 │ 2 │ 0 │ 1 │
└───┴───┴───┴───┴───┴───┘

but it matches ⛔「⟨     ³ʳᵈa ²ⁿᵈb ¹ˢᵗc   ⟩, a > b > c」, which is a contradiction.

------------------------------

We have verified (8). Accordingly, we get

       ┌───┬───┬───┬───┬───┬───┐
       │ 5■│4th│3rd│2nd│1st│0th│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
Step 1 │ 1 │   │   │   │   │   │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │ 2 │ 5 │ 0 │ 3 │ 4 │
└───┴───┴───┴───┴───┴───┘

Then, to avoid ⛔「max ⊢1⊣ ≥ 3」, we need [4th] = 0|2. In view of ✅「⟨⋯ 3 ⋯ 0 ⋯⟩」, it is 2 indeed.

       ┌───┬───┬───┬───┬───┬───┐
       │5th│ 4■│3rd│2nd│1st│0th│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
       │ 1 │   │   │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 2 │ 1 │ 2 │   │   │   │   │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │   │ 5 │ 0 │ 3 │ 4 │
└───┴───┴───┴───┴───┴───┘

Plainly, to avoid ⛔「Jump(2,4) ≥ 1」, we then obtain

       ┌───┬───┬───┬───┬───┬───┐
       │5th│4th│ 3■│2nd│1st│0th│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
       │ 1 │ 2 │   │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 3 │ 1 │ 2 │ 4 │   │   │   │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │   │ 5 │ 0 │ 3 │   │
└───┴───┴───┴───┴───┴───┘

By ⛔「5th → a, 2nd → b, a+b=4」, we cannot place 3 at 2nd. So, in view of ✅「⟨⋯ 3 ⋯ 0 ⋯⟩」, we get

       ┌───┬───┬───┬───┬───┬───┐
       │5th│4th│3rd│2nd│ 1■│ 0■│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
       │ 1 │ 2 │ 4 │   │   │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 4 │ 1 │ 2 │ 4 │   │ 3 │   │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 5 │ 1 │ 2 │ 4 │   │ 3 │ 0 │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │   │ 5 │   │   │   │
└───┴───┴───┴───┴───┴───┘

As a result, we finish by

       ┌───┬───┬───┬───┬───┬───┐
       │5th│4th│3rd│ 2■│1st│0th│▒
       ╞═══╪═══╪═══╪═══╪═══╪═══╡▒
       │ 1 │ 2 │ 4 │   │ 3 │ 0 │▒
       ├───┼───┼───┼───┼───┼───┤▒
Step 6 │ 1 │ 2 │ 4 │ 5 │ 3 │ 0 │▒
       └───┴───┴───┴───┴───┴───┘▒
        ▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒

--- Idle ---
┌───┬───┬───┬───┬───┬───┐
│   │   │   │   │   │   │
└───┴───┴───┴───┴───┴───┘

Q.E.D.

#125034_v2.8