The New Sudoku Players' Forum

[Kites]

I finished this puzzle by guessing. Can you help solving it the logical way?
What is the next move? Please.....

*58 1** ***
471 6*2 ***
*6* **8 17*

74* 8*1 2**
*3* *6* **1
186 2*3 *59

613 789 *2*
597 426 318
824 315 697

[Addlan]

I finished this puzzle by guessing. Can you help solving it the logical way?
What is the next move? Please.....

*58 1** ***
471 6*2 ***
*6* **8 17*

74* 8*1 2**
*3* *6* **1
186 2*3 *59

613 789 *2*
597 426 318
824 315 697

Look at column 6 and 8, '4' can only be put in r1c6, r1c8, r5c6, r5c8. Because two columns and two rows should only have two '4's, so other grids in row 1 and row 5 won't have digit '4' except the above grids and you can eliminate the possibility of '4's in other grids. People call it X-wing, look at more about X-wing in the forum or people's website if you still don't know what it is.

[russ]

Alternatively, one of r4c3 and r3c4 contains 5 and the other 9
so r3c3 cannot be 9 (or 5, but we knew that already).

[Kites]

Thank you very much for your reply. I am not very clear about the X wing and am very interested in finding more about it, but don't know where to find it in the forum, or where to find the people's website. please help.

[quote="Addlan"][quote="Kites"]I finished this puzzle by guessing. Can you help solving it the logical way?
What is the next move? Please.....

*58 1** ***
471 6*2 ***
*6* **8 17*

74* 8*1 2**
*3* *6* **1
186 2*3 *59

613 789 *2*
597 426 318
824 315 697[/quote]

Look at column 6 and 8, '4' can only be put in r1c6, r1c8, r5c6, r5c8. Because two columns and two rows should only have two '4's, so other grids in row 1 and row 5 won't have digit '4' except the above grids and you can eliminate the possibility of '4's in other grids. People call it X-wing, look at more about X-wing in the forum or people's website if you still don't know what it is.[/quote]

[Kites]

Thanks Russ. My alternatives in r3c3 are = 29, in r4c3 = 59, r5c3 =259
also r3c4=59 as r5c4=59
Why r3c3 cannot be 9?

[quote="russ"]Alternatively, one of r4c3 and r3c4 contains 5 and the other 9
so r3c3 cannot be 9 (or 5, but we knew that already).[/quote]

[simes]

My attempt at an explanation is here

(It's been both praised and criticised, so form your own opinion!)

Simes

[russ]

Thanks Russ. My alternatives in r3c3 are = 29, in r4c3 = 59, r5c3 =259
also r3c4=59 as r5c4=59
Why r3c3 cannot be 9?

whatever r3c4 is [5 or 9], r5c4 is the other [9 or 5]
so r4c5 is the same as r3c4 [5 or 9]
so r4c3 is [9 or 5]

r3c3 must be different to r3c4 and r4c3 and so
must be different to (5 and) 9

so it's 2

[aleph]

Hi Addlan,
need help to understand the logic from your proposal... (asking for your patience )

what I found out is
Row1: {2,3,9}, 5, 8 | 1, {3479}, {4,7} | {4,9}, {3,4,6}, {2,3,4,6}
Row5: {2,9}, 3, {2,5,9} | {5,9}, 6, {4,7} | {4,7,8}, {4,8}, 1


the quartet you mention is r1c6, r1c8, r1c8, r5c8 or
{4,7}, {3,4,6}, {4,7}, {4,8}

I can also have '4' in r1c7 and r5c7... and therefore am not seeing how the x wing applies here

TIA for your help.

luis

I finished this puzzle by guessing. Can you help solving it the logical way?
What is the next move? Please.....

*58 1** ***
471 6*2 ***
*6* **8 17*

74* 8*1 2**
*3* *6* **1
186 2*3 *59

613 789 *2*
597 426 318
824 315 697

Look at column 6 and 8, '4' can only be put in r1c6, r1c8, r5c6, r5c8. Because two columns and two rows should only have two '4's, so other grids in row 1 and row 5 won't have digit '4' except the above grids and you can eliminate the possibility of '4's in other grids. People call it X-wing, look at more about X-wing in the forum or people's website if you still don't know what it is.