Extreme level sudoku

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Extreme level sudoku

Postby urhegyi » Tue Jan 05, 2021 3:26 pm

A member on a sudoku group asked for harder sudokus. So I genererated one myself. Advice on solving appreciated.
Code: Select all
007020090080010000000004628039070004800000000050900000200007060000040300000500019

nr1.png
nr1.png (15.34 KiB) Viewed 78 times
urhegyi
 
Posts: 220
Joined: 13 April 2020

Re: Extreme level sudoku

Postby denis_berthier » Wed Jan 06, 2021 4:09 am

SER 7.8

***********************************************************************************************
*** SudoRules 20.1.s based on CSP-Rules 2.1.s, config = W+SFin
*** Using CLIPS 6.32-r779
***********************************************************************************************
9 singles
163 candidates, 778 csp-links and 778 links. Density = 5.89%
whip[1]: c8n3{r6 .} ==> r6c9 ≠ 3, r5c9 ≠ 3
whip[1]: c8n5{r5 .} ==> r4c7 ≠ 5
whip[1]: r3n1{c3 .} ==> r1c2 ≠ 1, r1c1 ≠ 1
finned-x-wing-in-rows: n2{r9 r4}{c7 c6} ==> r6c6 ≠ 2
whip[1]: r6n2{c9 .} ==> r4c7 ≠ 2
finned-swordfish-in-rows: n6{r2 r4 r8}{c4 c6 c1} ==> r9c1 ≠ 6
Code: Select all
RESOLUTION STATE AT THIS POINT:
   3456      46        7         368       2         3568      15        9         13       
   3569      8         2         36        1         3569      57        4         37       
   1359      19        135       7         359       4         6         2         8         
   16        3         9         1268      7         12568     18        58        4         
   8         2         16        4         356       1356      9         357       167       
   7         5         4         9         368       1368      128       38        126       
   2         149       138       138       389       7         48        6         5         
   1569      1679      1568      1268      4         12689     3         78        27       
   34        467       368       5         368       2368      2478      1         9         

Nothing noticeable after that, except that it doesn't use whips even though they were active:
Hidden Text: Show
z-chain[3]: c4n2{r4 r8} - c9n2{r8 r6} - r6n6{c9 .} ==> r4c4 ≠ 6
finned-x-wing-in-rows: n6{r4 r2}{c1 c6} ==> r1c6 ≠ 6
t-whip-cn[3]: c3n6{r9 r5} - c9n6{r5 r6} - c5n6{r6 .} ==> r9c2 ≠ 6
t-whip[3]: r6c8{n3 n8} - r4c7{n8 n1} - r6n1{c9 .} ==> r6c6 ≠ 3
biv-chain[4]: r9c1{n3 n4} - r9c2{n4 n7} - c7n7{r9 r2} - r2c9{n7 n3} ==> r2c1 ≠ 3
biv-chain[4]: r1n4{c1 c2} - r9c2{n4 n7} - c7n7{r9 r2} - b3n5{r2c7 r1c7} ==> r1c1 ≠ 5
z-chain[4]: r1c2{n6 n4} - r1c1{n4 n3} - c9n3{r1 r2} - r2c4{n3 .} ==> r2c1 ≠ 6
whip[1]: r2n6{c6 .} ==> r1c4 ≠ 6
hidden-pairs-in-a-row: r1{n4 n6}{c1 c2} ==> r1c1 ≠ 3
whip[1]: b1n3{r3c3 .} ==> r3c5 ≠ 3
t-whip[4]: r5c3{n1 n6} - c9n6{r5 r6} - r6n2{c9 c7} - r6n1{c7 .} ==> r5c6 ≠ 1
t-whip[4]: r9c1{n3 n4} - r1c1{n4 n6} - r4n6{c1 c6} - c5n6{r6 .} ==> r9c5 ≠ 3
biv-chain[5]: c3n5{r8 r3} - b1n3{r3c3 r3c1} - r9c1{n3 n4} - r1c1{n4 n6} - b4n6{r4c1 r5c3} ==> r8c3 ≠ 6
finned-x-wing-in-columns: n6{c3 c5}{r9 r5} ==> r5c6 ≠ 6
biv-chain[2]: c3n6{r9 r5} - r4n6{c1 c6} ==> r9c6 ≠ 6
swordfish-in-columns: n6{c3 c5 c9}{r5 r9 r6} ==> r6c6 ≠ 6
biv-chain[3]: r5c6{n3 n5} - c5n5{r5 r3} - b2n9{r3c5 r2c6} ==> r2c6 ≠ 3
biv-chain[4]: r4c7{n8 n1} - r5n1{c9 c3} - c3n6{r5 r9} - r9c5{n6 n8} ==> r9c7 ≠ 8
biv-chain[4]: r9n2{c6 c7} - r6n2{c7 c9} - r6n6{c9 c5} - r9c5{n6 n8} ==> r9c6 ≠ 8
hidden-pairs-in-a-row: r9{n6 n8}{c3 c5} ==> r9c3 ≠ 3
biv-chain[4]: c5n5{r3 r5} - r5c6{n5 n3} - r9n3{c6 c1} - b1n3{r3c1 r3c3} ==> r3c3 ≠ 5
hidden-single-in-a-column ==> r8c3 = 5
finned-swordfish-in-columns: n8{c3 c5 c7}{r7 r9 r6} ==> r6c8 ≠ 8
naked-single ==> r6c8 = 3
naked-pairs-in-a-column: c5{r6 r9}{n6 n8} ==> r7c5 ≠ 8, r5c5 ≠ 6
naked-pairs-in-a-block: b5{r5c5 r5c6}{n3 n5} ==> r4c6 ≠ 5
singles ==> r4c8 = 5, r5c8 = 7, r8c8 = 8, r7c7 = 4
naked-pairs-in-a-column: c2{r3 r7}{n1 n9} ==> r8c2 ≠ 9, r8c2 ≠ 1
x-wing-in-columns: n9{c2 c5}{r3 r7} ==> r3c1 ≠ 9
biv-chain-rc[4]: r5c6{n5 n3} - r9c6{n3 n2} - r9c7{n2 n7} - r2c7{n7 n5} ==> r2c6 ≠ 5
biv-chain[3]: c4n6{r8 r2} - r2c6{n6 n9} - c1n9{r2 r8} ==> r8c1 ≠ 6
naked-pairs-in-a-block: b7{r7c2 r8c1}{n1 n9} ==> r7c3 ≠ 1
biv-chain[4]: c9n2{r6 r8} - r8n7{c9 c2} - b7n6{r8c2 r9c3} - c5n6{r9 r6} ==> r6c9 ≠ 6
stte

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denis_berthier
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