Problem with the killer sudoku of june 9

[Ron@ldK]

Good afternoon,

I am a fan of the sum- or killersudoku's so I downloaded the killers from june. I have a problem with the killer from june 9.

The SumoCue-program gives me a solution wich I don't underderstand. The program gives me the following step 'Naked single 1 found in r3 c6.

Unfortunately I am not succeeding in posting the grid here.

Here is the ps-code of the grid:
3x3::k:4096:40963842:4356:5381:5381:4359:4359:409638504356:53812831:43593850:5140:5140:4356232738662322:5140:4382:43822327386628524382413731145165:5165:41434137:4137363651654143:41433891415739033383:51865188:4157:415739035186:51865188:51883143:

Who helps me.

Thnx,
Ronald[/code]

[Ruud]

Hi Ronald,

welcome to the forum. Glad you like the killers posted on my website.

to post a candidate grid on the forum, press Control+M in SumoCue and paste it into your message. Put the [code] tags around it to make it more readable.

This is the state of the puzzle in which the progam suggests a naked single in r3c6. To arrive at this stage, you need to work through a series of steps with triple outies for rows 1 and 2 and some advanced reduction of candidates in the upper region of the puzzle.

Code: Select all

.-----------------------.-----------------------.-----------.-----------------------.-----------------------.
|(16)                   |(15)                   |(17)       |(21)                   |(17)                   |
| 123456789   123456789 | 123456789   123456789 | 123456789 | 456789      56789     | 123456789   123456789 |
|           .-----------'-----------.           |           |           .-----------'-----------.           |
|           |(15)                   |           |           |           |(11)                   |           |
| 123456789 | 123456789   123456    | 123456789 | 123456789 | 456789    | 124         1234      | 123456789 |
:-----------:           .-----------'-----------:           :-----------'-----------.           :-----------:
|(9)        |           |(20)                   |           |(9)                    |           |(15)       |
| 123456    | 56789     | 3456789     3456789   | 56789     | 1           35        | 5678      | 123456789 |
|           '-----------:           .-----------'-----------+-----------.           :-----------'           |
|                       |           |(17)                   |(12)       |           |                       |
| 123456      123456    | 3456789   | 123456789   123456789 | 123456789 | 35        | 123456789   123456789 |
:-----------------------'-----------:           .-----------+-----------+-----------'-----------------------:
|(11)                               |           |           |(16)       |(12)                               |
| 12345678    12345678    123456    | 123456789 | 123456789 | 123456789 | 124         123456789   123456789 |
:-----------------------.-----------+-----------+-----------'           :-----------.-----------------------:
|(20)                   |(16)       |           |                       |(15)       |(14)                   |
| 3456789     3456789   | 123456789 | 123456789 | 123456789   123456789 | 356789    | 123456789   123456789 |
|           .-----------:           '-----------+-----------.-----------'           :-----------.           |
|           |(13)       |                       |(11)       |                       |(16)       |           |
| 3456789   | 123456789 | 123456789   123456789 | 12345678  | 123456789   356789    | 356789    | 123456789 |
:-----------:           '-----------.-----------:           :-----------.-----------'           :-----------:
|(15)       |                       |(20)       |           |(20)       |                       |(12)       |
| 123456789 | 123456789   123456    | 3456789   | 12345678  | 3456789   | 124         356789    | 123456789 |
|           '-----------.-----------'           |           |           '-----------.-----------'           |
|                       |                       |           |                       |                       |
| 123456789   123456789 | 3456789     3456789   | 12345678  | 3456789     356789    | 123456789   123456789 |
'-----------------------'-----------------------'-----------'-----------------------'-----------------------'

As you can see, there is only one candidate left in r3c6. This is caused by the pair in the remaining 2 cells of the cage. If you are having trouble with sudoku terminology like "naked single", you should do a bit of reading in my solving guide. As you probably know, the solving strategies for regular sudoku can also be used in killers. My Assassins are handmade and I often manage to slip a in few advanced solving tricks.

Enjoy the rest of the series. July's killers are a little easier, but the August puzzle is back to its usual deadly level.

Ruud

[Ron@ldK]

Hi Ruud,

Thnx for answering my question. Unfortunately I still don't get it.

When looking at the 7 steps before getting to the given solution of digit 1 in r3c6.

Step 1: 45 test eliminates in 3 outies of rows 1,2
It leaves 9 for the 3 outies, that implies three combinations for
the 9, 1,2,6 / 1,3,5 and 2,3,4

Step 2: Unplaceable candidate in cage 11(3) in nonet 3
In my opinion only the 9 is not placeable.

Step 3: 45 test eliminates in 3 outies of rows 1,2
I don't see the difference with step 1

Step 4: 45 test eliminates in 3 outies of rows 8,9
It leaves 9 for the 3 outies, that implies three combinations for
the 9, 1,2,6 / 1,3,5 and 2,3,4

Step 5: Unplaceable candidates in cage 16(3) in nonet 9
I don't see any candidates

Step 6: Naked subset of size 3 found in column 7
What is the meaning of this

Step 7: Unplaceable candidates in cage 9(3) in nonet 2,3,6
The combination for 9 can be 1,2,6 / 1,3,5 or 2,3,4 , so 7,8,9 are
not placeable.

Step 8: Digit 1 is placed in r3c6

Can you please explain some of the steps to me.

Tnx again,
Ronald

[Ruud]

Step 1: 45 test eliminates in 3 outies of rows 1,2
It leaves 9 for the 3 outies, that implies three combinations for
the 9, 1,2,6 / 1,3,5 and 2,3,4

The 3 outies add up to (16+15+17+21+17+15+11-90) = 22. Since it cannot go below {589}, all candidates 1,2,3 & 4 are scrapped.

Step 2: Unplaceable candidate in cage 11(3) in nonet 3
In my opinion only the 9 is not placeable.

This is the result of your incorrect calculation in step 1. Because the outie must be 5 or higher, the other 2 digits must add up to 6 or less, but {15} is impossible because it would result in a repeating 5.

Step 3: 45 test eliminates in 3 outies of rows 1,2
I don't see the difference with step 1

Read carefully: it reads "columns" and not "rows"
The outies add up to 9 (maybe you tested the columns in step 1?). The highest possible number is 6 in {126}

Step 4: 45 test eliminates in 3 outies of rows 8,9
It leaves 9 for the 3 outies, that implies three combinations for
the 9, 1,2,6 / 1,3,5 and 2,3,4

Again: Columns, not rows. The surplus is 7 for the 3 outies. {124} is the only configuration for that.

Step 5: Unplaceable candidates in cage 16(3) in nonet 9
I don't see any candidates

I like this one. Hard to find indeed. The outie cell has {124} after the preious step. If you press X (show configurations) you will see that there are no configurations that contain 2 of these digits, which means that the other 2 cells cannot place them.

Step 6: Naked subset of size 3 found in column 7
What is the meaning of this

Step 4 caused 3 cells in column 7 with candidates {124}. These 3 cells will be the ONLY spots in column 7 that can contain 1, 2 or 4. All other cells in column 7 can be cleared of these digits. For more details, read my online solving guide.

Step 7: Unplaceable candidates in cage 9(3) in nonet 2,3,6
The combination for 9 can be 1,2,6 / 1,3,5 or 2,3,4 , so 7,8,9 are
not placeable.

This is because you did not take the previous step into account. The 2 cells in column 7 no longer have digits 1,2 & 4 as candidate. As a result, the combination {126} no is longer valid. This eliminates 6. Now the 2 cells in column 7 only allow {3,5}, so the other cell can only be 1.

Step 8: Digit 1 is placed in r3c6

Perfectly logical.


Difficult killers like these must be handled with care. Read the hints carefully, do not confuse rows & columns, and check your calculations.

Ruud

[Ron@ldK]

Thanks a lot,

It's now perfectly clear to me.

I wasn't careful enough and it was all due to my miscalculation.

Ronald