The New Sudoku Players' Forum

by **al_bell** » Wed Apr 16, 2008 8:41 pm

Code: Select all: Without Pencil Marks . . 9 | . . 8 | . . . . . . | . 3 . | . 4 . . . 7 | . . . | . . 5 ------+-------+------ . . 8 | . . . | 9 . . 3 . . | . 4 . | . . 2 . . 6 | . . . | 7 . . ------+-------+------ 2 . . | . . . | 5 . . . 1 . | . 5 . | . . . . . . | 6 . . | 8 . . With Pencil Marks 145 345 9 | 1245 12 8 | 23 67 67 568 568 2 | 579 3 579 | 1 4 89 148 348 7 | 124 69 126 | 23 89 5 ------------+------------------+-------------- 457 245 8 | 1235 67 12356 | 9 135 134 3 79 1 | 589 4 579 | 6 58 2 459 245 6 | 123589 89 12359 | 7 135 1348 ------------+------------------+-------------- 2 68 4 | 13789 789 1379 | 5 1679 1679 68 1 3 | 289 5 279 | 4 2679 679 79 79 5 | 6 12 4 | 8 123 13

I am wondering what the next step should be and why.

thank you

by **ArkieTech** » Wed Apr 16, 2008 9:27 pm

Code: Select all: .------------------------.------------------------.------------------------. | 145 345 9 | 1245 12 8 | 23 67 67 | | 568 568 2 | 579 3 579 | 1 4 89 | | 148 348 7 | 124 A69 126 | 23 89 5 | :------------------------+------------------------+------------------------: | 457 245 8 | 1235 A67 12356 | 9 135 134 | | 3 79 1 |B589 4 B579 | 6 B58 2 | | 459 245 6 | 123589 8-9 12359 | 7 135 1348 | :------------------------+------------------------+------------------------: | 2 68 4 | 13789 789 1379 | 5 1679 1679 | | 68 1 3 | 289 5 279 | 4 2679 679 | | 79 79 5 | 6 12 4 | 8 123 13 | '------------------------'------------------------'------------------------' ALS:A(679)B(5789)C(7)=>r6c5<>9 later ur(67)=>r7c8=1

dan

by **storm_norm** » Thu Apr 17, 2008 12:23 am

Code: Select all: 145 345 9 | 1245 12 8 | 23 67 67 568 568 2 | 579 3 5679 | 1 4 89 1468 3468 7 | 1249 6(9) 1269 | 23 #89 5 ------------------------------------------------------------------ 457 2457 8 | 12357 67 123567 | 9 135 134 3 579 1 |#5789 4 579 | 6 #58 2 459 2459 6 | 123589 89# 12359 | 7 1358 1348 ------------------------------------------------------------------ 2 68 4 | 13789 789 1379 | 5 1679 1679 68 1 3 | 2789 5 279 | 4 2679 679 79 79 5 | 6 12 4 | 8 123 13

the # marked in the grid is a W-wing on {8,9}...
the pair {8,9} can see the strong link on 8's in row 5 and the associated 9's see the 9 in r3c5.
that solves r3c5 as 6 directly.

leaves you with this...

Code: Select all: 14 34 9 | 5 12 8 | 23 #67 #67 56 56 2 | 7 3 9 | 1 4 89 18 38 7 | 4 6 12 | 23 9 5 ------------------------------------------------------------------ 45 245 8 | 123 7 6 | 9 135 134 3 579 1 | 5789 4 579 | 6 8 2 9 245 6 | 123 8 123 | 7 135 134 ------------------------------------------------------------------ 2 68 4 | 138 9 137 | 5 #1(67) #67 68 1 3 | 28 5 27 | 4 267 9 79 79 5 | 6 12 4 | 8 123 13

the cells marked # is a type 1 UR on {6,7} and removes {6,7} from r7c8 and solves r7c8 as 1 and solves the puzzle.

by **tarek** » Thu Apr 17, 2008 6:04 pm

ArkieTech wrote:
Code: Select all
.------------------------.------------------------.------------------------. | 145 345 9 | 1245 12 8 | 23 67 67 | | 568 568 2 | 579 3 579 | 1 4 89 | | 148 348 7 | 124 A69 126 | 23 89 5 | :------------------------+------------------------+------------------------: | 457 245 8 | 1235 A67 12356 | 9 135 134 | | 3 79 1 |B589 4 B579 | 6 B58 2 | | 459 245 6 | 123589 8-9 12359 | 7 135 1348 | :------------------------+------------------------+------------------------: | 2 68 4 | 13789 789 1379 | 5 1679 1679 | | 68 1 3 | 289 5 279 | 4 2679 679 | | 79 79 5 | 6 12 4 | 8 123 13 | '------------------------'------------------------'------------------------' ALS:A(679)B(5789)C(7)=>r6c5<>9 later ur(67)=>r7c8=1

dan

Isn't r5c2 part of you B set ???

I couldn't spot it myself. My solver says 2 ALS-XY, doubles & UR-1

tarek

by **ArkieTech** » Thu Apr 17, 2008 7:14 pm

Isn't r5c2 part of you B set ???

Wouldn't that take the "Almost" out of it -- making 4 candidates for 4 cells?
I look for 4 candidates to go into 3 cells with a common. I am new at this and just learning....Help!

dan

by **hobiwan** » Thu Apr 17, 2008 7:34 pm

ArkieTech wrote:Wouldn't that take the "Almost" out of it -- making 4 candidates for 4 cells?
I look for 4 candidates to go into 3 cells with a common. I am new at this and just learning....Help!

dan

As far as I can see your ALS-XZ is perfectly valid.

by **tarek** » Thu Apr 17, 2008 8:00 pm

hobiwan wrote:
ArkieTech wrote:Wouldn't that take the "Almost" out of it -- making 4 candidates for 4 cells?
I look for 4 candidates to go into 3 cells with a common. I am new at this and just learning....Help!

dan

As far as I can see your ALS-XZ is perfectly valid.

Absolutely, I was confused when looking at the C(7) & thought it was an ALS-XY.

This is the last time that I will try replying while thinking about something else

Good one ArkieTech

tarek

by **ttt** » Sat Apr 19, 2008 3:58 pm

Code: Select all: I am wondering what the next step should be and why.

Based on Arkie Tech meant that :
1- If r5c468=(triple 589) => r6c6<>9
2- If r5c468<>(triple 589) => r5c6=7 => r4c5=6 => r3c5=9 => r6c6<>9

by **ArkieTech** » Sat Apr 19, 2008 4:06 pm

ttt said:

1- If r5c468=(triple 589) => r6c6<>9
2- If r5c468<>(triple 589) => r5c6=7 => r4c5=6 => r3c5=9 => r6c6<>9

Excellent! I like it.

dan

by **wintder** » Sat Apr 19, 2008 5:34 pm

storm_norm wrote:the # marked in the grid is a W-wing on {8,9}...
the pair {8,9} can see the strong link on 8's in row 5 and the associated 9's see the 9 in r3c5.
that solves r3c5 as 6 directly.

storm_norm, I like this route.

by **daj95376** » Sat Apr 19, 2008 7:03 pm

ttt wrote:Based on Arkie Tech:

1- If r5c468=589 => r5c2=7 => r6c1=9 => r6c5<>9
2- If r5c468<>589 => r5c6=7 => r4c5=6 => r3c5=9 => r6c5<>9

I like it too. It reminds me of the (old-style?) double implication chain where [r5c2]=7 or [r5c6]=7.

by **storm_norm** » Sun Apr 20, 2008 6:53 pm

wintder wrote:
storm_norm wrote:the # marked in the grid is a W-wing on {8,9}...
the pair {8,9} can see the strong link on 8's in row 5 and the associated 9's see the 9 in r3c5.
that solves r3c5 as 6 directly.

storm_norm, I like this route.

thank you, me too.

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