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PostPosted: Sun Mar 22, 2009 1:05 pm 
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All sudoku puzzles in this forum post are the intellectual property of Børge Alexander Tetlie Anderssen.
Copyright © 2009 Børge Alexander Tetlie Anderssen. All rights reserved. Terms of Use.


There are four difficulties to choose from.
All four puzzles have the same solution.
The difficulty levels explained     The ratings explained

A) Apprentice 1:  Moderate
B) Apprentice 2: Tough
C) Apprentice 3: Hard
D) Master: Super Hard
Below a cloaked list of the advanced techniques needed in the format: TECHNIQUE on DIGIT(s) in GRID, TECHNIQUE on DIGIT(s) in GRID, ...
:arrow: Skyscraper on 9 in g6, Uniqueness Test 1 on {46} in g6, Two String Kite on 3 in g8


Another Gattai-8 #A (Apprentice 1)

Rating based on required solving techniques:  Moderate

Image

000600081003090000840000090090003002020000130080070005007300000000000000004012000
003900000000300091006002000050406000000000600608103040000030000000000000000009000
004009018001007000000000200000000702000098500503016900000000000000004090000031607
000109000000000000000000000000000000530701000000005008000000000000200000000006000
000702000000000000000306000000040300792000000000000709000100000000000000000083000
900000000000000000000235000005020000000070003604001200000060010100809000050100002
000060000000309000000000000000805000000026030060090100030000000050008400100030029
000000000000001070000500400010007005020004108000090700100405000096270000000000624



Another Gattai-8 #B (Apprentice 2)

Rating based on required solving techniques:  Tough

Image

000600081003090000840000090090000002020000130080270905007350000000000000004010000
003900000000000091006002000050400000000000600608103040000038000000000000000009000
000029018001007000000000200008000702000098500503016900000000000000004090000031000
000109000000007000000000000000000150530701000000005008000070000000200000000006000
000702000000000000000006000000040300792000000000000709000100000000000000000080000
900000000000000000000235000075420000000070003004001200400060000100809030050100002
000060000000309000000000000300805000000020000060090100030000800050008400100000029
000700000000001200000500400019007005020004108000090000000005000090270000000000624



Another Gattai-8 #C (Apprentice 3)

Rating based on required solving techniques:  Hard

Image

000600081003090000840000090090003002020000030080070005007300000000000000004012000
003900200000300091006002000050400030000000600008103040000038000000000000000009000
054009010001007000000000200008000702000090500500016900000000000000004093000031600
000109000000000000000000000000000000530701000100005008000070000000200000000006000
000702000000000000000006000000047000002000000000000709000100000000000000000083000
900000000000000000010205000075420000000070003604001200400060000100809000050100002
000060000000309000000000000300805090000020030060090100030000000050018400000030029
000000000000001270000500400010007005020000108000090000100405000090200000000000624



Another Gattai-8 #D (Master)

Rating based on required solving techniques:  Super Hard

Image

000600080003090000840000000090000002020000030080070905007350000000000000034012000
003900200080300091006002000050400000000000600008103040000008000000000000000009000
054009010001007000000000200008000702000090500000016900000000000000004093000031607
000109000000007000000000000000000100530700000100005008000070000000200000000006000
000702000000000000000006000000040300702030000000000009000100000000000000000080000
940000000000000000000235000075020000000070003600001200400060010100809000050100002
000060000000309000000000000000805090000026000000000100030000000050018400100030029
000700000000001200000500400019007005000004108000090000000005000096270000000000624

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Last edited by Børge on Fri May 01, 2009 8:50 pm, edited 1 time in total.

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PostPosted: Tue Mar 24, 2009 2:31 pm 
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Oh, fun! :bouncy: Good timing, too! :applause:

I just knocked out several puzzles on my trip to Italy last week (10.5-hour flight back to the U.S., and no way to see out the window :evil: ). A couple of them (from the Cross+A site at http://www.cross-plus-a.com/sudoku.htm) were boringly easy (mostly naked singles). :roll: I think I may have identified a bug in JSudoku's pencil-mark calculation, which I'll explore further in another thread.

I tried to slog through the Christmas Shogun (Journeyman edition) again, but made very little progress (a previously-missed set of locked candidates that didn't get me very far). Now that I have access to a computer again, I'll have to plug it into a solver and figure out what else I'm missing.

In the mean time, I'll give these a shot. I'm at the "Hard" level and trying to work my way up to "Very Hard". I'm getting better at finding N/H triples and quads, and I'm starting to get the hang of XY-wings (when I can find them). I can sometimes find a swordfish, but I have yet to find one that actually eliminates any candidates, probably because I don't find the swordfish until at least the second pass through the puzzle, after most of the N/H sets and locked candidates have been found. I haven't even looked into jellyfish or squirmbag yet, though.


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PostPosted: Tue Mar 24, 2009 8:38 pm 
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Just a short warning:
Another Gattai-8 #C is a toughie :D 8-)
A large Naked Subset (or a tiny bit smaller Hidden Subset) is needed before any of the eight 9x9 subgrids are completely solved.

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PostPosted: Sat Mar 28, 2009 12:14 am 
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Børge wrote:
Just a short warning:
Another Gattai-8 #C is a toughie :D 8-)
A large Naked Subset (or a tiny bit smaller Hidden Subset) is needed before any of the eight 9x9 subgrids are completely solved.

Thanks for the warning! :D I'm working my way through #A. So far, so good. I've been trying to get through at least one grid each evening before I get so tired I can't see straight anymore.


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PostPosted: Tue Mar 31, 2009 2:23 am 
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I finished the #A edition today. Now I'm trying to go back to the Christmas 2008 Shogun (Journeyman edition) to see if I can figure out what I'm missing, but I'm having trouble with SudokuSolver's hint function. (I really don't want it to give me the next step outright.)


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PostPosted: Wed Apr 01, 2009 9:22 pm 
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enxio27 wrote:
Now I'm trying to go back to the Christmas 2008 Shogun (Journeyman edition) to see if I can figure out what I'm missing, ....
Try examining g6:n4 and g7:r4

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PostPosted: Thu Apr 02, 2009 3:03 am 
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Børge wrote:
enxio27 wrote:
Now I'm trying to go back to the Christmas 2008 Shogun (Journeyman edition) to see if I can figure out what I'm missing, ....
Try examining g6:n4 and g7:r4

By g6 and g7, do you mean the center and rightmost grids in the center row? And by n4 do you mean r4-6 c1-3 ? If so, I found the triplet and quad in g7:r4 and the 2 in g6:r4c1, but not much else in those two locations. What am I not seeing?

Here's what I have so far for those two:

Grid 6:

.-------------------------------.-------------------------------.-------------------------------.
| 356 368 2358 | 2689 4 23689 | 7 1689 1269 |
| 367 9 2378 | 268 36 1 | 24 5 234 |
| 136 4 1238 | 256789 3569 2356789 | 2689 689 2369 |
:-------------------------------+-------------------------------+-------------------------------:
| 2 5 1678 | 3 169 689 | 689 4 6789 |
| 13678 368 13678 | 4 1569 5689 | 3689 2 6789 |
| 4 368 9 | 268 7 268 | 5 1368 168 |
:-------------------------------+-------------------------------+-------------------------------:
| 58 1 58 | 679 369 34679 | 2346 3679 2469 |
| 36 7 346 | 1 2 349 | 348 389 5 |
| 9 2 34 | 567 8 34567 | 1 367 46 |
'-------------------------------.-------------------------------.-------------------------------'


Grid 7:

.-------------------------------.-------------------------------.-------------------------------.
| 23459 2345 234 | 7 15 6 | 1289 128 289 |
| 1269 8 26 | 239 15 239 | 27 2457 247 |
| 1259 1257 27 | 29 8 4 | 139 135 6 |
:-------------------------------+-------------------------------+-------------------------------:
| 1468 146 1468 | 48 2 57 | 579 79 3 |
| 2348 9 2348 | 1 6 57 | 24578 278 2578 |
| 7 24 5 | 348 9 38 | 248 6 1 |
:-------------------------------+-------------------------------+-------------------------------:
| 3456 34567 379 | 289 347 1 | 23678 23478 478 |
| 12346 123467 1237 | 5 347 28 | 36789 34789 4789 |
| 2348 2347 23789 | 6 347 29 | 1257 1247 457 |
'-------------------------------.-------------------------------.-------------------------------'


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PostPosted: Thu Apr 02, 2009 7:07 pm 
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enxio27 wrote:
By g6 and g7, do you mean the center and rightmost grids in the center row?
YES.
As our host Richard once wrote: Grids are strictly numbered from top left to bottom right (except for Clueless Grids, which are always last) [But also numbered from top left to bottom right if there are more than one clueless grid].

enxio27 wrote:
And by n4 do you mean r4-6 c1-3 ?
What else? ;)
n4 is the de facto standard abbreviation for nonet 4. Nonets are also strictly numbered from top left to bottom right!

Unfortunately I made a typo. I meant g6:n7 and not g6:n4. Sorry about that. But you have found the hidden pair in g6:n7. With g7:r4 I referred to the triplet and quad you have found.

Based on your listed state for g6, JSudoku suggests that you have missed an Intersection on an even digit in g2, which results in Naked Singles in g2:r3c38. If you have those, you have forgotten to eliminate pencil marks after placing the solution in g2:r3c8.
g2 and g6 shares a nonet, i.e. g2:n9≡g6:n1

Hope this helps.

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PostPosted: Thu Apr 02, 2009 7:34 pm 
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Børge wrote:
enxio27 wrote:
By g6 and g7, do you mean the center and rightmost grids in the center row?
YES.

Børge wrote:
enxio27 wrote:
And by n4 do you mean r4-6 c1-3 ?

n4 is the de facto standard abbreviation for nonet 4.

OK, I wanted to make sure my numbering follows the standard.
Quote:
Based on your listed state for g6, JSudoku suggests that you have missed an Intersection on an even digit in g2, which results in Naked Singles in g2:r3c38. If you have those, you have forgotten to eliminate pencil marks after placing the solution in g2:r3c8.

Boy, I sure don't see it! I went through g2 again, with special attention to the section you mentioned. I'm guessing that the intersection you mention is the 4 in r3c2 and r3c3, but I don't see what is eliminating the 4 in the rest of the nonet or the row. Here's what I have for g2:

.-------------------------------.-------------------------------.-------------------------------.
| 789 34679 34679 | 1479 2478 2489 | 134567 13678 134578 |
| 789 34679 2 | 1479 478 5 | 13467 13678 13478 |
| 1 457 457 | 6 3 48 | 2 78 9 |
:-------------------------------+-------------------------------+-------------------------------:
| 2 136789 136789 | 479 478 3489 | 13479 5 1347 |
| 5 1379 1379 | 2 6 349 | 8 137 1347 |
| 4 3789 3789 | 579 578 1 | 379 2 6 |
:-------------------------------+-------------------------------+-------------------------------:
| 79 479 479 | 38 1 26 | 356 368 2358 |
| 36 128 18 | 45 245 246 | 367 9 2378 |
| 36 258 58 | 38 9 7 | 136 4 1238 |
'-------------------------------.-------------------------------.-------------------------------'


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PostPosted: Fri Apr 03, 2009 12:14 pm 
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enxio27 wrote:
I'm guessing that the intersection you mention is the 4 in r3c2 and r3c3, but I don't see what is eliminating the 4 in the rest of the nonet or the row
No. I thought you had missed an intersection on 8 in g2, but you have not.

When JSudoku deploys the Intersection on 8, its g6 and g7 states are pretty similar to yours. Its g2 is however quite a bit more developed than yours.

Can it be that you have missed a Hidden Single in g5:c9 or g5:n9?
If not, please check the following locations for Naked Subsets. JSudoku lists them prior to the Naked Quad in g7:r4 and the Hidden Pair in g6:n7.
g1:n3
g7:n8
g7:n5

If none of this helps, please post the complete text based candidate grid for the complete puzzle, so that I can paste it into JSudoku. I will then post its next move as a vague hint. Before posting please verify that the complete text based candidate grid (from SudokuSolver I presume) is understood by JSudoku.

It should look something like this:
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 14 2 14 | 8 3 9 | 56 56 7 | | 3789 346789 346789 | 14789 2478 2489 | 134567 134678 134578 | | 2459 2459 2459 | 1 6 7 | 8 239 23 | | 4 23678 1 | 2356 25679 25679 | 5789 2789 2789 |
| 5 78 9 | 1267 267 1267 | 48 3 248 | | 3789 346789 2 | 14789 478 5 | 13467 134678 13478 | | 1 7 8 | 2 3 9 | 456 456 456 | | 279 267 5 | 26 12679 8 | 179 4 3 |
| 378 6 378 | 27 4 5 | 9 28 1 | | 1 4578 4578 | 6 3 48 | 2 478 9 | | 3 269 269 | 58 58 4 | 7 29 1 | | 23789 2378 23789 | 235 4 12579 | 15789 6 2789 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 34789 1 3478 | 3679 6789 3678 | 2 45689 45689 | | 23789 1236789 136789 | 34789 478 3489 | 13479 5 12347 | | 4568 3 1456 | 458 7 2 | 1456 1456 9 | | 5 9 278 | 1 3 4 | 678 278 2678 |
| 2 78 6 | 5 789 4 | 1 89 3 | | 5 1379 1379 | 2 6 349 | 8 13479 1347 | | 245689 1245689 124569 | 34589 14589 1358 | 123456 1234567 234567 | | 1238 12348 2348 | 7 269 269 | 489 289 5 |
| 3489 5 348 | 12369 2689 12368 | 468 7 4689 | | 4 23789 3789 | 35789 578 1 | 379 2379 6 | | 2459 12459 7 | 3459 1459 6 | 12345 12345 8 | | 6 247 247 | 8 259 259 | 479 3 1 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 678 9 278 | 23467 25678 23678 | 345 1 245 | 2345 8 6 | 2379 2479 3479 | 3458 1 23468 | 356 2368 2358 | 25689 4 235689 | 7 15689 12569 | 45689 24589 58 | 23459 23458 234 | 7 15 6 | 1289 1248 2489 | 246 1267 1267 | 3 5 46789 |
| 1678 4 1278 | 23679 256789 23678 | 35678 2569 25689 | 23457 2479 2347 | 2368 1248 1348 | 3458 2458 23468 | 35679 2346789 234578 | 2568 356 1 | 2468 568 23456 | 7 124589 1358 | 124569 124568 246 | 239 15 239 | 278 24578 24678 | 9 256 3 | 68 1 468 |
| 678 3 5 | 24679 1 2678 | 4678 2469 24689 | 1 2479 2347 | 2368 2458 3458 | 348 9 7 | 136 123468 12348 | 256789 3569 2356789 | 24689 5689 234569 | 345689 124589 1358 | 12569 12567 267 | 29 8 4 | 139 135 69 | 456 8 1567 | 2 79 4679 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| | | 569 3 569 | 2467 2467 247 | 14789 14789 14789 | | 2 5 1678 | 3 169 689 | 1689 4 16789 | | 1468 146 1468 | 48 2 57 | 579 79 3 | | |
| | | 2 47 47 | 8 1 9 | 5 3 6 | | 13678 13678 13678 | 4 1569 5689 | 13689 2 16789 | | 2348 9 2348 | 1 6 57 | 24578 278 2578 | | |
| | | 1 8 69 | 467 3 5 | 479 479 2 | | 4 1368 9 | 268 7 268 | 5 1368 168 | | 7 24 5 | 348 9 38 | 248 6 1 | | |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 1 247 2457 | 245 6 3 | 489 2479 2789 | 23467 5 1 | 2347 2467 37 | 34 467 9 | 58 123467 58 | 679 369 34679 | 2346 3679 2469 | 1469 8 123469 | 23456 234567 2379 | 289 347 1 | 23678 23478 478 | 14678 9 1678 | 12347 12478 5 |
| 2567 2467 3 | 245 8 9 | 46 2467 1 | 23467 2467 23478 | 34789 45678 35789 | 2 1 3478 | 36 3467 3467 | 1 2 34679 | 3468 356789 45689 | 469 23479 23469 | 12346 123467 1237 | 5 347 28 | 36789 34789 4789 | 5 2 1678 | 1347 1478 1467 |
| 9 8 246 | 24 7 1 | 456 2456 3 | 9 2467 2478 | 12478 124678 178 | 5 4678 3478 | 369 234679 23467 | 567 8 34567 | 12346 367 1246 | 469 23479 5 | 2348 2347 23789 | 6 347 29 | 1257 1247 457 | 4678 3 678 | 9 2478 2467 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 2378 1237 127 | 6 4 5 | 12389 1289 289 | | 13478 13478 1378 | 148 5 24678 | 13468 12346 9 | | 2457 2459 24579 | 3 6 8 | 1257 1257 127 | | 4 689 89 | 12678 1678 3 | 5 127 127 |
| 368 5 9 | 7 13 2 | 13468 1468 68 | | 1458 9 158 | 148 3 2468 | 7 12456 24568 | | 23578 2358 2578 | 145 245 124 | 9 23578 6 | | 58 568 3 | 12678 1678 1678 | 1247 1247 9 |
| 236 12346 1246 | 39 139 8 | 7 1256 256 | | 6 134578 2 | 1489 4789 478 | 13458 1345 3458 | | 23568 1 2568 | 7 259 29 | 2358 2358 4 | | 17 17 2 | 9 4 5 | 8 6 3 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+
| 23567 12367 12567 | 389 39 4 | 15689 156789 56789 | | 123589 12358 6 | 3489 2489 3458 | 3459 34579 3457 | | 9 24568 1245678 | 4568 345 346 | 1234678 1234678 12378 | | 278 2478 6 | 3 178 9 | 1247 5 1247 |
| 4 9 8 | 1 5 67 | 26 3 267 | | 23579 2357 3579 | 6 249 345 | 3459 8 1 | | 1468 468 1468 | 2 349 7 | 13468 134689 5 | | 23578 23578 1 | 78 578 4 | 6 9 27 |
| 3567 1367 1567 | 389 2 67 | 15689 156789 4 | | 3589 358 4 | 7 89 1 | 2 3569 356 | | 245678 24568 3 | 45689 1 469 | 24678 246789 278 | | 579 4579 4579 | 167 1567 2 | 147 3 8 |
+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+----------------------------+

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