This is my first time to use Medusa 3D coloring (M3D). I was able to solve the

following puzzle, but I have some questions. The M3D rules from sudokuwiki.org

are after line 73. At line 88 I start the coloring. At line 119 I note some

'collisions' with the two colors. I did not see a rule that covered that.

1. Did I assign the color and its 'opposite' correctly? Line 88+

2. Did I manage the collision between colors correctly? Line 119+

3. Did I extend the 'opposite' color correctly? Line 149+

4. Is my logic OK in 'opposite' color was not part of the solution? ~Line 177

5. If the above are OK, why did my eliminations not agree with HoDoKu? Line 177+

I was able to solve the problem, but I wanted help with my procedure! Thanks!

Unfair (4274) by HoDoKu - v2.1.3

- Code: Select all
`1 . . | . 8 . | 5 3 .`

. . 3 | . 9 7 | . 6 .

. . . | . . . | . 8 7

------+-------+------

. . . | . . . | . 7 .

6 . 1 | . 4 . | 3 . 2

. 2 . | . . . | . . .

------+-------+------

7 1 . | . . . | . . .

. 8 . | 5 6 . | 7 . .

. 6 4 | . 7 . | . . 8

Solution:

- Code: Select all
`1 4 7 | 2 8 6 | 5 3 9`

8 5 3 | 4 9 7 | 2 6 1

2 9 6 | 3 5 1 | 4 8 7

------+-------+------

4 3 8 | 6 2 9 | 1 7 5

6 7 1 | 8 4 5 | 3 9 2

5 2 9 | 7 1 3 | 8 4 6

------+-------+------

7 1 5 | 9 3 8 | 6 2 4

9 8 2 | 5 6 4 | 7 1 3

3 6 4 | 1 7 2 | 9 5 8

Line 43:

r2c1=8, r2c2=5, r4c2=3, n2r23c7 => r79c7<>2, n4r46c1 => r3c1<>4,

n8r5c46 => r46c46<>8

- Code: Select all
`1 . . | . 8 . | 5 3 .`

8 5 3 | . 9 7 | . 6 .

. . . | . . . | . 8 7

------+-------+------

. 3 . | . . . | . 7 .

6 . 1 | . 4 . | 3 . 2

. 2 . | . . . | . . .

------+-------+------

7 1 . | . . . | . . .

. 8 . | 5 6 . | 7 . .

. 6 4 | . 7 . | . . 8

- Code: Select all
`.-----------------.---------------------.--------------------.`

| 1 479 2679 | 246 8 246 | 5 3 49 |

| 8 5 3 | 124 9 7 | 124 6 14 |

| 29 49 269 | 12346 1235 123456 | 1249 8 7 |

:-----------------+---------------------+--------------------:

| 459 3 589 | 1269 125 12569 | 14689 7 14569 |

| 6 79 1 | 789 4 589 | 3 59 2 |

| 459 2 5789 | 13679 135 13569 | 14689 1459 14569 |

:-----------------+---------------------+--------------------:

| 7 1 259 | 23489 23 23489 | 469 2459 34569 |

| 239 8 29 | 5 6 12349 | 7 1249 1349 |

| 2359 6 4 | 1239 7 1239 | 19 1259 8 |

'-----------------'---------------------'--------------------'

Line 73:

3D-Medusa Elimination Rules - Summary from sudowiki.org

1. same color twice in a cell eliminates that color

2. twice in a house for same digit eliminates that color

3. 2 colors in a cell eliminates that candidate in the cell

4. 2 colors in a unit for same candy - all candidates that can

see both colors can be eliminated

5. 2 colors elsewhere that can see same candidate that

candidate can be removed

6. any un-colored candidate that sees a colored candidate

elsewhere and OPPOSITE colored candidate in same cell

it can be removed

Line 88:

Using Hodoku Player: 3D Medusa coloring

red = one color at n49r2c2=9

lt-red = 'opposite' color at n49r1c9=4, red is 9 at this BV cell

(firstly is the correct procedure?)

red start at n49r3c2

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

01 9 r3c2=9 by choice

02 9 r1c9=9

03 7 r5c2=7

04 7 r1c3=7

05 7 r6c4=7

06 4 r1c2=4

07 2 r3c1=2

08 2 r2c7=2

09 6 r3c3=6

red-light choose n49r1c9=4

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

01 4 r1c9=4

02 1 r2c9=1n

03 2 r2c7=2n - red

04 9 r3c7=9n

05 4 r3c2=4n - 9 is red

06 2 r3c1=2n - red

07 6 r3c3=6n - red

08 4 r2c4=4n

Line 119:

Note we have some collisions of colors in cells.

It is not explicitly in Medusa 3D (M3D) rules, but I assume if

a candie in a cell is colored with two 'opposite' colors

(red & red-light are just that) then that candie must be

a solution.

I proceeded from here, but have some problems with some of the eliminations

Continuing Trace where opposite colors indicate same cell is solution

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

-07 2 r2c7=2n opposite colors agree

-08 2 r3c1=2n opposite colors agree

-09 6 r3c3=6n opposite colors agree

-10 26 n26r1c46 => r1c46=26

So I eliminate the collisions and reorder and renumber the

red cells and the light-red cells:

red start at n49r3c2 red-light choose n49r1c9=4

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

01 9 r3c2=9 by choice 01 4 r3c2=4n by choice

02 4 r1c2=4n 02 4 r1c9=4

03 7 r1c3=7bcr 03 4 r2c4=4n

04 9 r1c9=9br 04 1 r2c9=1n

05 7 r5c2=7n 05 9 r3c7=9n

06 7 r6c4=7bcr

Line 149:

Seeing no additions to red, look at light red

06 1 r9c7=1n

07 1 r6c8=1bc

08 1 r8c6=1br

09 4 r7c6=4bc

10 4 r8c8=4r

11 6 r7c7=6n

12 8 r7c4=8br

13 8 r5c6=8bcr

14 39 r8c19=39 => r8c3=2

15 79 r5c24=79 => r5c8=5

16 5 r7c9=5bc

17 5 r9c1=5br

18 9 r7c3=9n

19 9 r1c2=9br

20 9 r8c9=9r

21 2 r7c8=2n

22 3 r8c1=3n

23 7 r1c3=7n

24 6 r46c9=6 same color of same candie in a house

25 7 r5c2=7 for both colors

So light-red cannot be part of a solution

delete all light-red candies

Line 177: x marks a conflict with what HoDoKu says is a valid elimination-why?

-11 r1c2<>9

-12 r1c9<>4

-13 r2c4<>4 x

-14 r2c9<>1 x

-15 r3c2<>4

-16 r3c7<>9

-17 r7c3<>9

-18 r7c4<>8

-19 r7c6<>4

-20 r7c7<>6 x

-21 r7c8<>2 x

-22 r7c9<>5 -

-23 r8c1<>3

-24 r8c2<>2

-25 r8c6<>1

-26 r8c8<>4

-27 r8c9<>9

-28 r9c1<>5

-29 r9c7<>1

Line 199: Start using the first few eliminations and then just solved from there.

-30 r1c2=4n

-31 r1c9=9n

-32 r3c2=9n

-33 r5c2=7n

-34 r6c1=7bcr

-35 r9c1=3bc

-36 r8c1=9n

-37 r8c3=2n

-38 r8c3=5n

-39 r9c8=5n

-39 r5c8=9n

-40 r5c4=8n

-41 r5c6=5n

-42 r7c8=2bc

-43 r3c5=5bcr

-44 r7c6=8bcr

-45 r7c5=3n

-46 r6c5=1n

-47 r4c5=2n Cost2=0

-48 r8c9=3bcr

-49 r6c6=3br

-50 r3c4=3bcr Cost3=0

-51 r6c8=4n

-52 r4c1=4bcr

-53 r8c6=4r

-54 r2c4=4bc

-55 r3c7=4br

-56 r7c9=4bcr

-57 r2c9=1n

-58 r3c6=1n

-59 r4c7=1br

-60 r8c8=1n

-61 r9c4=1bcr Cost1=0

-62 2 r1c4=2c

-63 2 r9c6=2bcr Cost2=0

-64 5 r6c1=5n

-65 5 r4c9=5n Cost5=0

-66 6 r1c6=6n

-67 6 r4c4=6c

-68 6 r6c9=6n

-69 6 r7c7=6br Cost6=0

-70 8 r6c7=8n

-71 8 r3c3=8bcr Cost8=0

-72 9 r4c6=9n

-73 9 r6c3=9n

-74 9 r7c4=9n

-75 9 r9c7=9n Cost9=0 Done!

147286539853497261296351487438629175671845392529713846715938624982564713364172958

- Code: Select all
`.---------.---------.---------.`

| 1 4 7 | 2 8 6 | 5 3 9 |

| 8 5 3 | 4 9 7 | 2 6 1 |

| 2 9 6 | 3 5 1 | 4 8 7 |

:---------+---------+---------:

| 4 3 8 | 6 2 9 | 1 7 5 |

| 6 7 1 | 8 4 5 | 3 9 2 |

| 5 2 9 | 7 1 3 | 8 4 6 |

:---------+---------+---------:

| 7 1 5 | 9 3 8 | 6 2 4 |

| 9 8 2 | 5 6 4 | 7 1 3 |

| 3 6 4 | 1 7 2 | 9 5 8 |

'---------'---------'---------'