The New Sudoku Players' Forum

by **daj95376** » Wed Mar 19, 2008 4:09 pm

Yesterday, I started this thread and then deleted it because I wanted to reconsider its format. Today, I'm back to repost and discover that eleven has posted a hard "17" of his own. Talk about timing! Anyway, I'll post a few and see if anyone's interested in the content.

by **daj95376** » Wed Mar 19, 2008 4:11 pm

"17" puzzle #46556. It gets contrary with 18 cells remaining.

Code: Select all: .1.....2....8..6.......3........43....2.1....8......9.4...7.5.3...2...........4.. .134.7825..48.263128.1.3947....243183429187568.1.36294429671583.382451.91..3894.2 r4c2 <> 57 Unique Rectangle Type 1

Code: Select all: *-----------------------------------------------------------* | 69 1 3 | 4 69 7 | 8 2 5 | | 579 579 4 | 8 59 2 | 6 3 1 | | 2 8 56 | 1 56 3 | 9 4 7 | |-------------------+-------------------+-------------------| | 5679 69 567 | 57 2 4 | 3 1 8 | | 3 4 2 | 9 1 8 | 7 5 6 | | 8 57 1 | 57 3 6 | 2 9 4 | |-------------------+-------------------+-------------------| | 4 2 9 | 6 7 1 | 5 8 3 | | 67 3 8 | 2 4 5 | 1 67 9 | | 1 567 567 | 3 8 9 | 4 67 2 | *-----------------------------------------------------------*

by **daj95376** » Wed Mar 19, 2008 4:12 pm

"17" puzzle #12481. It gets contrary with 19 cells remaining.

Code: Select all: ...87..3.52.......4..........3.9..7......54...8.......2.....5.....3....9...1..... 1..8742355279638414385219676534981727126354989842173562..7..5.38..3....93..1....4

Code: Select all: +-----------------------------------------------------+ | 1 69 69 | 8 7 4 | 2 3 5 | | 5 2 7 | 9 6 3 | 8 4 1 | | 4 3 8 | 5 2 1 | 9 6 7 | |-----------------+-----------------+-----------------| | 6 5 3 | 4 9 8 | 1 7 2 | | 7 1 2 | 6 3 5 | 4 9 8 | | 9 8 4 | 2 1 7 | 3 5 6 | |-----------------+-----------------+-----------------| | 2 469 169 | 7 48 69 | 5 18 3 | | 8 467 156 | 3 45 26 | 67 12 9 | | 3 679 569 | 1 58 269 | 67 28 4 | +-----------------------------------------------------+

by **daj95376** » Wed Mar 19, 2008 4:15 pm

"17" puzzle #42341. It gets contrary with 19 cells remaining.

Code: Select all: ..15............32...............2.9.5...3......7..8..27.....4.3...9.......6..5.. 7315269845..9...32.923...15..31..27995728346112.7.98532798..346365497128.1.632597 c26 X-Wing F/S <> 4 [r2c5]

Code: Select all: +-----------------------------------------------------+ | 7 3 1 | 5 2 6 | 9 8 4 | | 5 48 468 | 9 17 148 | 67 3 2 | | 468 9 2 | 3 47 48 | 67 1 5 | |-----------------+-----------------+-----------------| | 468 48 3 | 1 456 45 | 2 7 9 | | 9 5 7 | 2 8 3 | 4 6 1 | | 1 2 46 | 7 46 9 | 8 5 3 | |-----------------+-----------------+-----------------| | 2 7 9 | 8 15 15 | 3 4 6 | | 3 6 5 | 4 9 7 | 1 2 8 | | 48 1 48 | 6 3 2 | 5 9 7 | +-----------------------------------------------------+

by **hobiwan** » Wed Mar 19, 2008 4:29 pm

daj95376, what does "contrary" mean?

daj95376 wrote:
Code: Select all
..15............32...............2.9.5...3......7..8..27.....4.3...9.......6..5.. 7315269845..9...32.923...15..31..27995728346112.7.98532798..346365497128.1.632597 c26 X-Wing F/S <> 4 [r2c5]

I can't see an X-Wing. Did you mean X-Chain?

by **hobiwan** » Wed Mar 19, 2008 7:29 pm

Nice puzzles!

#46556: I need an ALS for that.
#12481: UR Type 4 and XY-Chain
#42341: W-Wing, XY-Chain and BUG+1

Do you see other possibilities?

by **daj95376** » Wed Mar 19, 2008 8:32 pm

hobiwan wrote:daj95376, what does "contrary" mean?

can't see an X-Wing. Did you mean X-Chain?

contrary: stubborn, uncooperative

The finned X-Wing elimination in 4 occurs prior to the PM. You may have been confused because I also used F for Franken. I'll update my solver to use f/s for finned/sashimi in the future.

Code: Select all: +-----------------------------------+ | . . . | . . . | . . 4 | | . *4 4 | . -4 *4 | . . . | | 4 . . | . 4 #4 | . . . | |-----------+-----------+-----------| | 4 *4 . | . 4 *4 | . . . | | . . . | . . . | 4 . . | | . . 4 | . 4 . | . . . | |-----------+-----------+-----------| | . . . | . . . | . 4 . | | . . . | 4 . . | . . . | | 4 . 4 | . . . | . . . | +-----------------------------------+

by **daj95376** » Wed Mar 19, 2008 8:45 pm

hobiwan wrote:Nice puzzles!

#46556: I need an ALS for that.
#12481: UR Type 4 and XY-Chain
#42341: W-Wing, XY-Chain and BUG+1

Do you see other possibilities?

I don't have chains incorporated (yet) into my new solver. My old solver produces networks and I have to manually search them for a useful chain. Also, I only have UR Type 1 and UR Type 2 implemented. Here's what I have for two of the puzzles. One is a single chain, the other is a forcing chain. I haven't tackled the middle puzzle, yet.

#46556:

Code: Select all: [r4c1]=5=[r2c1]-5-[r2c5]-9-[r1c5]-6-[r1c1]-9-[r4c1]; => [r4c1]<>9

#42341:

Code: Select all: [r6c3]-4-[r4c2]-8-[r4c1] -6-[r3c1] [r6c3]-6-[r6c5]-4-[r3c5]-7-[r3c7]-6-[r3c1] [r3c1]<>6

by **hobiwan** » Wed Mar 19, 2008 9:54 pm

daj95376 wrote:contrary: stubborn, uncooperative

Thanks. I thought it had some special meaning for sudokus. Next time I will check the dictionary first...

daj95376 wrote:The finned X-Wing elimination in 4 occurs prior to the PM. You may have been confused because I also used F for Franken. I'll update my solver to use f/s for finned/sashimi in the future.

Not your fault. I saw the Two-String-Kite/X-Chain [r6c5] - [r2c2] (connected through [r6c3] - [r4c2]) => [r2c5]<>4 and simply overlooked the X-Wing.

daj95376 wrote:#46556:
Code: Select all
[r4c1]=5=[r2c1]-5-[r2c5]-9-[r1c5]-6-[r1c1]-9-[r4c1]; => [r4c1]<>9

ALS XZ: A=[r2c15] - {579}, B=[r18c1] - {679}, X=7, Z=9 => [r2c2]<>9
Puzzle solves with singles

daj95376 wrote:#42341:
Code: Select all
[r6c3]-4-[r4c2]-8-[r4c1] -6-[r3c1] [r6c3]-6-[r6c5]-4-[r3c5]-7-[r3c7]-6-[r3c1] [r3c1]<>6

W-Wing: [r2c2] - [r9c1] connected through 8 in [r4c2] - [r4c1] => [r3c1]<>4
Locked Candidates 4 (b1/r2) => [r2c56]<>4
XY-Chain: [r2c2]-8-[r3c1]-6-[r3c7]-7-[r3c5]-4-[r6c5]-6-[r6c3] => [r2c3],[r4c2]<>4
Singles lead to BUG+1
Your solution is much better...

#12481:
UR Type 4 (6/7): [r89c7] - [r89c2] => [r89c2]<>6
XY-Chain: [r8c6]-6-[r8c7]-7-[r8c2]-4-[r8c5]-5-[r9c5]-8-[r9c8] => [r8c8],[r9c6]<>2

by **daj95376** » Wed Mar 19, 2008 11:55 pm

Puzzle #20425:

Code: Select all: .51..........2.4...........64....2.....5.1..7...3..6..4...3.......8...5.2........ .514.3.2636..254.1.2461.5.3643...215..25613475173426..4.523.16.1368.4.522..156.34

Code: Select all: b9 - 7 Locked Candidate (1) c37 X-Wing f/s (skyscraper) <> 8 [r1c1],[r2c8] r267 Swordfish f/s <> 9 [r3c6]

Code: Select all: *--------------------------------------------------* | 79 5 1 | 4 789 3 | 89 2 6 | | 3 6 8 | 79 2 5 | 4 79 1 | | 79 2 4 | 6 1 78 | 5 789 3 | |----------------+----------------+----------------| | 6 4 3 | 79 789 789 | 2 1 5 | | 8 9 2 | 5 6 1 | 3 4 7 | | 5 1 7 | 3 4 2 | 6 89 89 | |----------------+----------------+----------------| | 4 78 5 | 2 3 79 | 1 6 89 | | 1 3 6 | 8 79 4 | 79 5 2 | | 2 78 9 | 1 5 6 | 78 3 4 | *--------------------------------------------------*

by **daj95376** » Thu Mar 20, 2008 5:33 am

Puzzle #26572:

Code: Select all: 17.....4....62....5...3....84....1.....3....6......9....6.....3.....1..........5. 173..5642...627315562134...849256137721349586635718924.165.2..335...126.2...63.51

Code: Select all: *--------------------------------------------------* | 1 7 3 | 89 89 5 | 6 4 2 | | 49 89 48 | 6 2 7 | 3 1 5 | | 5 6 2 | 1 3 4 | 78 79 89 | |----------------+----------------+----------------| | 8 4 9 | 2 5 6 | 1 3 7 | | 7 2 1 | 3 4 9 | 5 8 6 | | 6 3 5 | 7 1 8 | 9 2 4 | |----------------+----------------+----------------| | 49 1 6 | 5 789 2 | 478 79 3 | | 3 5 478 | 489 789 1 | 2 6 89 | | 2 89 478 | 489 6 3 | 478 5 1 | *--------------------------------------------------*

by **daj95376** » Thu Mar 20, 2008 5:35 am

Puzzle #11258:

Code: Select all: ...7...1...6.......4.......7..5.1.....8...4..2...........24.6...3..8....1.......9 .257...1..76.1.....41......7945.1...6189..4..253...19.587249631439186...1623..849

Code: Select all: b5 - 8 Locked Candidate (1) r6 - 67 Naked Pair r14 - 3 X-Wing

Code: Select all: *--------------------------------------------------* | 8 2 5 | 7 39 4 | 39 1 6 | | 39 7 6 | 8 1 235 | 259 25 4 | | 39 4 1 | 6 259 235 | 7 8 235 | |----------------+----------------+----------------| | 7 9 4 | 5 23 1 | 23 6 8 | | 6 1 8 | 9 27 237 | 4 25 235 | | 2 5 3 | 4 6 8 | 1 9 7 | |----------------+----------------+----------------| | 5 8 7 | 2 4 9 | 6 3 1 | | 4 3 9 | 1 8 6 | 25 7 25 | | 1 6 2 | 3 57 57 | 8 4 9 | *--------------------------------------------------*

by **ronk** » Thu Mar 20, 2008 12:09 pm

Puzzle #11258: A BUG-Lite+2, aka a uniqueness loop (as illustrated on daj95376's pencilmarks) ...

Code: Select all: *---------------------------------------------------* | 8 2 5 | 7 39 4 |#39 1 6 | | 39 7 6 | 8 1 235 |*25+9 *25 4 | | 39 4 1 | 6 259 235 | 7 8 235 | |----------------+----------------+-----------------| | 7 9 4 | 5 23 1 | 2-3 6 8 | | 6 1 8 | 9 27 237 | 4 *25 *25+3 | | 2 5 3 | 4 6 8 | 1 9 7 | |----------------+----------------+-----------------| | 5 8 7 | 2 4 9 | 6 3 1 | | 4 3 9 | 1 8 6 |*25 7 *25 | | 1 6 2 | 3 57 57 | 8 4 9 | *---------------------------------------------------*

r4c7 -3- UL(25):(r5c9 =3|9= r2c7) -9- r1c7 -3- r4c7 ==> r4c7<>3

... leads to cascading singles.

Puzzle #20425: Not likely the simplest path, but a BUG-Lite+3 jumps out.

Code: Select all: *--------------------------------------------------* |*79 5 1 | 4 *79+8 3 |#89 2 6 | | 3 6 8 |*79 2 5 | 4 *79 1 | |*79 2 4 | 6 1 78 | 5 *79+8 3 | |----------------+----------------+----------------| | 6 4 3 |*79 *79+8 789 | 2 1 5 | | 8 9 2 | 5 6 1 | 3 4 7 | | 5 1 7 | 3 4 2 | 6 89 89 | |----------------+----------------+----------------| | 4 78 5 | 2 3 79 | 1 6 89 | | 1 3 6 | 8 #79 4 |#79 5 2 | | 2 78 9 | 1 5 6 | 78 3 4 | *--------------------------------------------------*

r4c5 -9- r8c5 -7- r8c7 -9- r1c7 -8- UL(79):(r1c5,r3c8 =8|8= r4c5) ==> r4c5<>9

... followed by an x-wing, an xy-wing and singles solves the puzzle.

[edit: added this simpler chain for the same elimination]

r4c5 -9- r8c5 -7- r8c7 -9- r1c7 -8- r1c5 =8= r4c5 ==> r4c5<>9

by **hobiwan** » Thu Mar 20, 2008 4:03 pm

ronk wrote:Puzzle #20425: Not likely the simplest path, but a BUG-Lite+3 jumps out.

I would really love having something like that jumping out at me...

I stick with simpler things:
W-Wing: 7 [r1c1] - [r8c5] connected through 9 in [r1c7] - [r8c7] => [r1c5]<>7
X-Wing: r18/c57 => [r4c5]<>9
BUG+1

ronk wrote:Puzzle #11258: A BUG-Lite+2, aka a uniqueness loop (as illustrated on daj95376's pencilmarks) ...

Looks fascinating, although I don't understand it (I will look it up as soon as I find some time).

Simple version:
W-Wing: 3 [r1c5] - [r2c1] connected through 9 in [r3c5] - [r3c1] => [r2c6]<>3

Puzzle #26572:
W-Wing: 9 [r1c5] - [r8c9] connected through 8 in [r7c5] - [r7c7] => [r8c5]<>9
XY-Wing: 8/9/7 in [r8c9] - [r7c8] - [r8c5] => [r7c5]<>7
W-Wing: 8 [r8c3] - [r9c7] connected through 4 in [r7c1] - [r7c7] => [r8c9],[r9c2]<>8

Looks like learning W-Wing was a good decision

by **Draco** » Thu Mar 20, 2008 5:32 pm

daj95376 wrote:Puzzle #26572:

Code: Select all
17.....4....62....5...3....84....1.....3....6......9....6.....3.....1..........5. 173..5642...627315562134...849256137721349586635718924.165.2..335...126.2...63.51

Code: Select all
*--------------------------------------------------* | 1 7 3 | 89 89 5 | 6 4 2 | | 49 89 48 | 6 2 7 | 3 1 5 | | 5 6 2 | 1 3 4 | 78 79 89 | |----------------+----------------+----------------| | 8 4 9 | 2 5 6 | 1 3 7 | | 7 2 1 | 3 4 9 | 5 8 6 | | 6 3 5 | 7 1 8 | 9 2 4 | |----------------+----------------+----------------| | 49 1 6 | 5 789 2 | 478 79 3 | | 3 5 478 | 489 789 1 | 2 6 89 | | 2 89 478 | 489 6 3 | 478 5 1 | *--------------------------------------------------*

I am still not sure I have the chain notations down, but try this:

r3c7=8 --> r7c7<>8 --> r7c5=8 ... and ...
r3c7=7 --> r3c8=9 --> r7c8=7

The endpoints let you state that r7c5<>7. From there the puzzle solves with singles and a couple of XY-Wings in the lower row of boxes.

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Contrary "17" Puzzles

Contrary "17" Puzzles