The New Sudoku Players' Forum

[paranoyak]

Hi there
For a some time I couldn’t solve this and I need your help.
Instead of giving the solution I would be appreciate if you teach me the way:)
Thanks in advance.

https://ibb.co/D4VcDck

[Serg]

Hi, paranoyak!
It seems my help is too late, but nevertheless...

Digit "2" cannot be placed in r6c9 cell, because maximal sum of the 3 rest cells 6+8+9 < 24. So, "2" can be placed in r6c6 cell only and should be eleminated from r5c6 cell. I am not sure this much help, but it's a small advance that was quickly discovered.

Serg

[denis_berthier]

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Just seen this thread.
Starting from your resolution state and using the approach developed in my book [PBCS] (https://www.researchgate.net/publication/356313228_Pattern-Based_Constraint_Satisfaction_and_Logic_Puzzles_Third_Edition), where you need to keep track of the combinations still possible in the black cells and to use them in chains mixing white and black cell data, there's a solution with whips[2]; it's easy because each of the whips remains in a single sector:

Code: Select all

 biv-chain[2]: vr5c7{n12347 n12356} - r9c7{n7 n5} ==> r6c7≠5, r7c7≠5, r8c7≠5
 biv-chain[2]: vr5c7{n12356 n12347} - r9c7{n5 n7} ==> r6c7≠7, r7c7≠7, r8c7≠7
 whip[2]: hr8c4{n36789 n45789} - r8c7{n3 .} ==> r8c8≠4
 whip[2]: hr7c6{n5678 n2789} - r7c7{n3 .} ==> r7c10≠2
 whip[2]: vr1c4{n123567 n123459} - r5c4{n6 .} ==> r7c4≠9, r4c4≠9, r6c4≠9
 hidden-single-in-magic-horiz-sector ==> r7c5=9
 w[1]-cell-to-verti-ctr  ==> vr1c4≠123459
 w[1]-ctr-to-verti-sector  ==> r5c4≠9
 hidden-single-in-magic-horiz-sector ==> r5c6=9
 w[1]-ctr-to-verti-sector  ==> r6c6≠6
 w[1]-ctr-to-verti-sector  ==> r4c6≠6
 w[1]-ctr-to-verti-sector  ==> r4c6≠5
 w[1]-ctr-to-verti-sector  ==> r6c6≠5
 w[1]-ctr-to-verti-sector  ==> r6c6≠7
 w[1]-ctr-to-verti-sector  ==> r6c6≠8
 biv-chain[2]: r7c4{n8 n7} - vr1c4{n123468 n123567} ==> r3c4≠8, r4c4≠8, r5c4≠8, r6c4≠8
 biv-chain[2]: vr1c4{n123468 n123567} - r7c4{n8 n7} ==> r3c4≠7, r4c4≠7, r5c4≠7, r6c4≠7
 naked-single ==> r5c4=6
 naked-pairs-in-verti-sector: c3{r5 r7}{n7 n8} ==> r6c3≠8, r6c3≠7, r4c3≠8, r4c3≠7, r3c3≠8, r3c3≠7
 whip[2]: hr4c1{n578 n479} - r4c3{n6 .} ==> r4c4≠4, r4c2≠4
 w[1]-cell-to-horiz-ctr  ==> hr4c1≠479
 w[1]-ctr-to-horiz-sector  ==> r4c3≠4
 whip[2]: hr4c1{n578 n389} - r4c3{n6 .} ==> r4c4≠3, r4c2≠3
 w1-tte

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