The New Sudoku Players' Forum

by **gurth** » Tue Nov 11, 2014 5:06 pm

This puzzle is rated 7.2 by SE. Just a bit harder than Simple Sudoku. I was never very keen (or good) at forcing chains, but I spent a lot of time bashing my head in vain to make progress. Of course, it's much too easy using contradiction nets. Just now I was thrilled to find a very elegant chain! I'll be interested to see who can come up with the prettiest solution of this one!

Code: Select all: ....3..1. 93.....8. ...7.9.46 .2.964..1 .6.1..4.. ..4.2.... 6......7. ..9.45... ..32..1.4 *-----------* |...|.3.|.1.| |93.|...|.8.| |...|7.9|.46| |---+---+---| |.2.|964|..1| |.6.|1..|4..| |..4|.2.|...| |---+---+---| |6..|...|.7.| |..9|.45|...| |..3|2..|1.4| *-----------*

by **JC Van Hay** » Tue Nov 11, 2014 6:28 pm

Code: Select all: +----------------+-----------------+--------------------+ | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | +----------------+-----------------+--------------------+ | 358 2 58(7) | 9 6 4 | (78) 35 1 | | 358 6 58(7) | 1 58(7) 378 | 4 (29) 29 | | 1 9 4 | 358 2 378 | 678 356 378 | +----------------+-----------------+--------------------+ | 6 4 2 | 38 189 138 | 589 7 3589 | | 7 1 9 | 368 4 5 | (268) 36(2) 238 | | 58 58 3 | 2 (79) 67 | 1 -6(9) 4 | +----------------+-----------------+--------------------+

6r8c7=*[9r9c8=(9-2)r5c8=2r8c8 - (2=*8)r8c7 - (8=7)r4c7 - 7r4c3=7r5c3 - 7r5c5=(7-9)r9c5=9r9c8] :=> -6r9c8; stte

by **Leren** » Tue Nov 11, 2014 8:34 pm

Code: Select all: *--------------------------------------------------------------------------------* | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | |--------------------------+--------------------------+--------------------------| | 358 2 578C | 9 6 4 | 78B 35 1 | | 358 6 578D | 1 578E 378 | 4 c2-9cH 29 | | 1 9 4 | 358 2 378 | 678 356 378 | |--------------------------+--------------------------+--------------------------| | 6 4 2 | 38 189 138 | 589 7 3589 | | 7 1 9 | 368 4 5 |a268aA b236 238 | | 58 58 3 | 2 79F 67 | 1 69bG 4 | *--------------------------------------------------------------------------------* Kraken cell r8c7: 2 r8c7 - r8c8 = r5c8 - 9 r5c8; 6 r8c7 - (6=9) r9c8 - 9 r5c8; 8 r8c7 - (8=7) r4c7 - r4c3 = r5c3 - r5c5 = (7-9) r9c5 = r9c8 - 9 r5c8; => - 9 r5c8; stte

Leren

by **pjb** » Wed Nov 12, 2014 12:09 am

Code: Select all: 4 7 568 | 568 3 268 | 259 1 259 9 3 156 | 4 15 126 | 257 8 257 2 58 158 | 7 158 9 | 3 4 6 ------------------------+----------------------+--------------------- 358 2 g578 | 9 6 4 |h78 35 1 358 6 f578 | 1 e578 d378 | 4 a29 29 1 9 4 | 358 2 d378 | 678 356 378 ------------------------+----------------------+--------------------- 6 4 2 | 38 189 138 | 589 7 3589 7 1 9 | 368 4 5 |i268 36-2 238 58 58 3 | 2 79 c67 | 1 b69 4

(2=9)r5c8-(9=6)r9c8*-(6=7)r9c6-r6c6=r5c5-r5c3=r4c3-(7=8)r4c7-(68=2)r8c7* => -2 r8c8; stte

Phil

by **gurth** » Wed Nov 12, 2014 5:04 am

JC Van Hay , Leren and Phil: thanks for your replies! So far so good, no problems with your solutions, which are very interesting to me; I'll comment further on each one after waiting a bit to see if any other solutions are forthcoming.

Website · by **denis_berthier** » Wed Nov 12, 2014 6:56 am

gurth wrote:This puzzle is rated 7.2 by SE. Just a bit harder than Simple Sudoku. I was never very keen (or good) at forcing chains, but I spent a lot of time bashing my head in vain to make progress. Of course, it's much too easy using contradiction nets. Just now I was thrilled to find a very elegant chain! I'll be interested to see who can come up with the prettiest solution of this one!
Code: Select all
....3..1. 93.....8. ...7.9.46 .2.964..1 .6.1..4.. ..4.2.... 6......7. ..9.45... ..32..1.4

Hi Gurth,
What "pretty solution" means is very subjective. In my view, it supposes it doesn't use overly complicated patterns but it doesn't suppose "single-step".
In any case, this puzzle can be solved using only very elementary patterns of maximum size 4:

Code: Select all: singles ==> r7c2 = 4, r1c1 = 4, r2c4 = 4, r6c2 = 9, r6c1 = 1, r8c2 = 1, r8c1 = 7, r7c3 = 2, r3c1 = 2, r1c2 = 7, r3c7 = 3 whip[1]: r7n5{c9 .} ==> r9c8 ≠ 5 whip[1]: c8n5{r6 .} ==> r4c7 ≠ 5, r5c9 ≠ 5, r6c7 ≠ 5, r6c9 ≠ 5 whip[1]: b7n8{r9c2 .} ==> r9c6 ≠ 8, r9c5 ≠ 8 hidden-pairs-in-a-row: r5{n2 n9}{c8 c9} ==> r5c9 ≠ 8, r5c9 ≠ 7, r5c9 ≠ 3, r5c8 ≠ 5, r5c8 ≠ 3 biv-chain[4]: c4n5{r6 r1} - c4n6{r1 r8} - r9c6{n6 n7} - c5n7{r9 r5} ==> r5c5 ≠ 5 singles ==> r6c4 = 5, r4c8 = 5, r4c1 = 3, r5c6 = 3 biv-chain[3]: c6n7{r6 r9} - r9n6{c6 c8} - b6n6{r6c8 r6c7} ==> r6c7 ≠ 7 biv-chain[4]: c5n9{r7 r9} - c5n7{r9 r5} - b5n8{r5c5 r6c6} - r7c6{n8 n1} ==> r7c5 ≠ 1 hidden-single-in-a-block ==> r7c6 = 1 hidden-pairs-in-a-block: b2{r2c5 r3c5}{n1 n5} ==> r3c5 ≠ 8 whip[1]: r3n8{c3 .} ==> r1c3 ≠ 8 biv-chain[4]: r2n7{c7 c9} - r6n7{c9 c6} - c6n8{r6 r1} - b2n2{r1c6 r2c6} ==> r2c7 ≠ 2 biv-chain[3]: c7n2{r8 r1} - r1n9{c7 c9} - r5c9{n9 n2} ==> r8c9 ≠ 2 biv-chain[3]: c7n6{r6 r8} - r8n2{c7 c8} - c8n3{r8 r6} ==> r6c8 ≠ 6 singles ==> r6c8 = 3, r6c7 = 6 biv-chain[2]: r6n8{c9 c6} - c5n8{r5 r7} ==> r7c9 ≠ 8 ;;; Resolution state RS1 whip[3]: r1n9{c7 c9} - r5c9{n9 n2} - b3n2{r2c9 .} ==> r1c7 ≠ 5 whip[3]: r5c9{n9 n2} - b3n2{r2c9 r1c7} - r1n9{c7 .} ==> r7c9 ≠ 9 biv-chain[4]: c4n6{r1 r8} - r8n3{c4 c9} - r7c9{n3 n5} - r1n5{c9 c3} ==> r1c3 ≠ 6 singles ==> r1c3 = 5, r3c2 = 8, r3c3 = 1, r2c3 = 6, r2c6 = 2, r3c5 = 5, r2c5 = 1, r9c2 = 5, r9c1 = 8, r5c1 = 5 biv-chain[4]: r8n3{c9 c4} - c4n6{r8 r1} - r1c6{n6 n8} - r6n8{c6 c9} ==> r8c9 ≠ 8 stte

There is also a solution using only reversible chains, based on g-candidates:

Code: Select all: ;;; Same as above until resolution state RS1 g-biv-chain[3]: c7n9{r7 r1} - b3n2{r1c7 r123c9} - r5c9{n2 n9} ==> r7c9 ≠ 9 g-biv-chain[3]: b3n2{r1c7 r123c9} - r5c9{n2 n9} - r1n9{c9 c7} ==> r1c7 ≠ 5 biv-chain[4]: r9n6{c6 c8} - b9n9{r9c8 r7c7} - r1c7{n9 n2} - b2n2{r1c6 r2c6} ==> r2c6 ≠ 6 singles ==> r2c6 = 2, r2c3 = 6, r1c3 = 5, r3c2 = 8, r3c3 = 1, r3c5 = 5, r2c5 = 1, r9c2 = 5, r9c1 = 8, r5c1 = 5 biv-chain[4]: r8n3{c9 c4} - c4n6{r8 r1} - r1c6{n6 n8} - r6n8{c6 c9} ==> r8c9 ≠ 8 stte

by **gurth** » Wed Nov 12, 2014 8:51 am

denis_berthier wrote:
gurth wrote:This puzzle is rated 7.2 by SE. Just a bit harder than Simple Sudoku. I was never very keen (or good) at forcing chains, but I spent a lot of time bashing my head in vain to make progress. Of course, it's much too easy using contradiction nets. Just now I was thrilled to find a very elegant chain! I'll be interested to see who can come up with the prettiest solution of this one!
Code: Select all
....3..1. 93.....8. ...7.9.46 .2.964..1 .6.1..4.. ..4.2.... 6......7. ..9.45... ..32..1.4

Hi Gurth,
What "pretty solution" means is very subjective. In my view, it supposes it doesn't use overly complicated patterns but it doesn't suppose "single-step".
In any case, this puzzle can be solved using only very elementary patterns of maximum size 4:
...

Yes, I agree that "pretty" is totally subjective! So perhaps I should enlarge a bit. The methods you offer here are far above my head, as I never knew anything about those techniques and probably never will. What I seek is the maximum ease and simplicity, using the most primitive methods possible. In this case, I want nothing more than one very simple and short 'OR' chain, to use the terminology of Bill Richter, which is the same as an AIC: based on the principle that strong-link pairs can be 'glued' into a chain by weak links, the two ends of the chain in that case are also strongly linked to each other, meaning that if one end is not true, the other end must be. A strong link is any 'OR' link, and that does not demand that it be a conjugate link, which is an 'EOR' (exclusive-or) link.

The Kraken was a totally unknown animal to me, but Leren's reply is perfectly clear and lucid without any such knowledge. I admire the ingeniousness of Van Hay's logic, though it is rather complex. My own solution is, however, simpler and shorter... than any of the others so far...

by **Leren** » Wed Nov 12, 2014 8:53 am

Here's a beautiful (to my mind) 3 step solution.

Code: Select all: *--------------------------------------------------------------* | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | |--------------------+--------------------+--------------------| |B358 2 B578 | 9 6 4 | 78 35 1 | | 358 6 578 | 1 T578 378 | 4 29 29 | | 1 9 4 | 358 2 378 | 678 T35-6 378 | |--------------------+--------------------+--------------------| | 6 4 2 | 38 189 138 | 589 7 3589 | | 7 1 9 | 368 4 5 | 268 236 238 | | 58 58 3 | 2 79 67 | 1 69 4 | *--------------------------------------------------------------*

Exocet : r4c1 r4c3 r5c5 r6c8 3578 => - 6 r6c8

Code: Select all: *--------------------------------------------------------------* | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | |--------------------+--------------------+--------------------| |B358 2 B578 | 9 6 4 | 78 35 1 | | 358 6 578 | 1 T78-5 378 | 4 29 29 | | 1 9 4 | 358 2 378 | 6 T35 78-3 | |--------------------+--------------------+--------------------| | 6 4 2 | 38 189 138 | 589 7 3589 | | 7 1 9 | 368 4 5 | 28 236 238 | | 58 58 3 | 2 79 67 | 1 69 4 | *--------------------------------------------------------------*

Exocet : r4c1 r4c3 r5c5 r6c8 3578 ; r6c9==r5c5 => - 5 r5c5, -3 r6c9

Code: Select all: *--------------------------------------------------------------* | 4 7 568 | 68 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | |--------------------+--------------------+--------------------| | 3 2 78 | 9 6 4 |c78 5 1 | | 58 6 578 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 e78 | 6 3 d78 | |--------------------+--------------------+--------------------| | 6 4 2 | 38 189 18 | 589 7 3589 | | 7 1 9 | 38-6 4 5 |b28 a26 238 | | 58 58 3 | 2 79 f67 | 1 9-6 4 | *--------------------------------------------------------------*

XY Chain (6=2) r8c8 - (2=8) r8c7 - (8=7) r4c7 - (7=8) r6c9 - (8=7) r6c6 - (7=6) r9c6 => - 6 r8c4, r9c8; stte

Leren

Website · by **denis_berthier** » Wed Nov 12, 2014 9:08 am

gurth wrote:The methods you offer here are far above my head, as I never knew anything about those techniques and probably never will. What I seek is the maximum ease and simplicity, using the most primitive methods possible.

I don't think you can find simpler patterns:
- whip[1] is the same thing as row-block interaction or column-block interaction (also called claiming and pointing)
- biv-chain and g-biv-chain is the same thing as the simplest AIC (with no ALS), resp. with and without grouped candidates.

I'm eager to see your simpler solution

by **David P Bird** » Wed Nov 12, 2014 11:43 am

Welcome back Gurth - that was quite a coffee break!

Denis this is the simplest solution I can find:
1: (5)r6c4 = (5-7)r5c5 = (7)r9c5 - (7=6)r9c6 - (6)r8c4 = (6)r1c4 => r1c4 <> 5
. . Singles (5)r6c4,r4c8, (3)r4c1,r5c6
2: (1)r7c6 = (1-9)r7c5 = (9-7)r9c5 = (7-8)r5c5 = (8)r6c6 - (8=1)r7c6 => r7c6 = 1
. . (15)HP:r23c5 => r3c5 <> 8
. . (8)box-line:b2r1 => r1c3 <> 8
3: (7)r2c9 = (7)r6c9 - (7)r6c6 = (7)r9c6 - (7=9)r9c5 - (9)r9c8 = (9-2)r5c8 = (2)r8c8 - (2)r8c7 = (259-7)r127c7 = (7)r2c9 => r2c9 = 7
4: (9=6)r9c8 - (6=3)r6c8 - (3=8)r6c9 - (8)r4c7 = (8)r4c3 - (8)r5c3 = (8)r5c5 - (8=9)r7c5 => r9c5 <> 9
Singles to the end.

You won't like the chain length of step 3, but using persistent equivalence marking, segments such as (7)r2c9 =[..]- (7)r9c5 are simple to spot.

by **eleven** » Wed Nov 12, 2014 5:45 pm

Hi Gurth,

With some uniqueness moves:

Code: Select all: +----------------+-----------------+--------------------+ | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | +----------------+-----------------+--------------------+ | 358 2 578 | 9 6 4 | 78 35 1 | | 358 6 578 | 1 578 a378 | 4 29 29 | | 1 9 4 | 358 2 a378 | 678 356 378 | +----------------+-----------------+--------------------+ | 6 4 2 |b38 189 138 | 589 7 3589 | | 7 1 9 |b368 4 5 | 268 236 238 | | 58 58 3 | 2 79 *67 | 1 69 4 | +----------------+-----------------+--------------------+

UR 15r23c35 => r23c3<>5
chain: (38=6)r78c4-(6=7)r9c6-(7=38)r56c6 => r6c4<>38

Code: Select all: +-------------------+-------------------+-------------------+ | 4 7 568 | 68 3 268 | 259 1 259 | | 9 3 16 | 4 15 126 | 257 8 257 | | 2 *58 *18 | 7 158 9 | 3 4 6 | +-------------------+-------------------+-------------------+ | 3 2 78 | 9 6 4 | 78 5 1 | |*58 6 *578 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 b78 | 678 36 378 | +-------------------+-------------------+-------------------+ | 6 4 2 | 38 e189 a18 | 589 7 3589 | | 7 1 9 | 368 4 5 | 268 236 238 | |*58 *58 3 | 2 d79 c67 | 1 69 4 | +-------------------+-------------------+-------------------+

DP 58rc23,r5c13,r9c12: {1r3c3=7r5c3}-(7=8)r4c3-(8=1)r3c3 => r3c3=1
chain: (1=8)r7c6-(8=7)r6c6-7r9c6=(7-9)r9c5=(9-1)r7c5=1r7c6 => r7c6=1

Code: Select all: +----------------+----------------+----------------+ | 4 7 5 | 68 3 68 | 29 1 29 | | 9 3 6 | 4 1 2 | 57 8 57 | | 2 8 1 | 7 5 9 | 3 4 6 | +----------------+----------------+----------------+ | 3 2 78 | 9 6 4 | 78 5 1 | | 5 6 78 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 78 |a678 b36 378 | +----------------+----------------+----------------+ | 6 4 2 | 38 89 1 | 589 7 358 | | 7 1 9 | 368 4 5 |d268 c236 38 | | 8 5 3 | 2 79 67 | 1 69 4 | +----------------+----------------+----------------+

chain: 6r6c7=(6-3)r6c8=(3-2)r8c8=r8c7 => r8c7<>6

Code: Select all: +----------------+----------------+----------------+ | 4 7 5 | 68 3 68 | 29 1 29 | | 9 3 6 | 4 1 2 | 57 8 57 | | 2 8 1 | 7 5 9 | 3 4 6 | +----------------+----------------+----------------+ | 3 2 78 | 9 6 4 | 78 5 1 | | 5 6 78 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 78 | 6 3 78 | +----------------+----------------+----------------+ | 6 4 2 | 38 89 1 |#589 7 #358 | | 7 1 9 |#368 4 5 | 28 26 38 | | 8 5 3 | 2 79 67 | 1 69 4 | +----------------+----------------+----------------+

BUG: one of r7c79,r8c4 must be 8 => r7c45, r8c79<>8

by **gurth** » Thu Nov 13, 2014 6:24 am

Leren wrote:Here's a beautiful (to my mind) 3 step solution.

Code: Select all
*--------------------------------------------------------------* | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | |--------------------+--------------------+--------------------| |B358 2 B578 | 9 6 4 | 78 35 1 | | 358 6 578 | 1 T578 378 | 4 29 29 | | 1 9 4 | 358 2 378 | 678 T35-6 378 | |--------------------+--------------------+--------------------| | 6 4 2 | 38 189 138 | 589 7 3589 | | 7 1 9 | 368 4 5 | 268 236 238 | | 58 58 3 | 2 79 67 | 1 69 4 | *--------------------------------------------------------------*

Exocet : r4c1 r4c3 r5c5 r6c8 3578 => - 6 r6c8
.........
.......

Leren

- 'Exocet' is Greek to me, and I can't follow this, but it looks so intriguing I think I will delve into it. Thanks very much for this inspiration!

by **gurth** » Thu Nov 13, 2014 6:48 am

eleven wrote:Hi Gurth,

With some uniqueness moves:
Code: Select all
+----------------+-----------------+--------------------+ | 4 7 568 | 568 3 268 | 259 1 259 | | 9 3 156 | 4 15 126 | 257 8 257 | | 2 58 158 | 7 158 9 | 3 4 6 | +----------------+-----------------+--------------------+ | 358 2 578 | 9 6 4 | 78 35 1 | | 358 6 578 | 1 578 a378 | 4 29 29 | | 1 9 4 | 358 2 a378 | 678 356 378 | +----------------+-----------------+--------------------+ | 6 4 2 |b38 189 138 | 589 7 3589 | | 7 1 9 |b368 4 5 | 268 236 238 | | 58 58 3 | 2 79 *67 | 1 69 4 | +----------------+-----------------+--------------------+

UR 15r23c35 => r23c3<>5
chain: (38=6)r78c4-(6=7)r9c6-(7=38)r56c6 => r6c4<>38
Code: Select all
+-------------------+-------------------+-------------------+ | 4 7 568 | 68 3 268 | 259 1 259 | | 9 3 16 | 4 15 126 | 257 8 257 | | 2 *58 *18 | 7 158 9 | 3 4 6 | +-------------------+-------------------+-------------------+ | 3 2 78 | 9 6 4 | 78 5 1 | |*58 6 *578 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 b78 | 678 36 378 | +-------------------+-------------------+-------------------+ | 6 4 2 | 38 e189 a18 | 589 7 3589 | | 7 1 9 | 368 4 5 | 268 236 238 | |*58 *58 3 | 2 d79 c67 | 1 69 4 | +-------------------+-------------------+-------------------+

DP 58rc23,r5c13,r9c12: {1r3c3=7r5c3}-(7=8)r4c3-(8=1)r3c3 => r3c3=1
chain: (1=8)r7c6-(8=7)r6c6-7r9c6=(7-9)r9c5=(9-1)r7c5=1r7c6 => r7c6=1
Code: Select all
+----------------+----------------+----------------+ | 4 7 5 | 68 3 68 | 29 1 29 | | 9 3 6 | 4 1 2 | 57 8 57 | | 2 8 1 | 7 5 9 | 3 4 6 | +----------------+----------------+----------------+ | 3 2 78 | 9 6 4 | 78 5 1 | | 5 6 78 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 78 |a678 b36 378 | +----------------+----------------+----------------+ | 6 4 2 | 38 89 1 | 589 7 358 | | 7 1 9 | 368 4 5 |d268 c236 38 | | 8 5 3 | 2 79 67 | 1 69 4 | +----------------+----------------+----------------+

chain: 6r6c7=(6-3)r6c8=(3-2)r8c8=r8c7 => r8c7<>6
Code: Select all
+----------------+----------------+----------------+ | 4 7 5 | 68 3 68 | 29 1 29 | | 9 3 6 | 4 1 2 | 57 8 57 | | 2 8 1 | 7 5 9 | 3 4 6 | +----------------+----------------+----------------+ | 3 2 78 | 9 6 4 | 78 5 1 | | 5 6 78 | 1 78 3 | 4 29 29 | | 1 9 4 | 5 2 78 | 6 3 78 | +----------------+----------------+----------------+ | 6 4 2 | 38 89 1 |#589 7 #358 | | 7 1 9 |#368 4 5 | 28 26 38 | | 8 5 3 | 2 79 67 | 1 69 4 | +----------------+----------------+----------------+

BUG: one of r7c79,r8c4 must be 8 => r7c45, r8c79<>8

Hi eleven, I love the UR stuff, I never even thought I could find or solve that UR, your work reveals a lot to me and shows me how it must be done.
The same applies to the DP (I don't even know what that stands for, seems to be a ULoop) - love it. The bug I must still look into. Thank you!

To everybody: my solution, starting from the diagram in JC Van Hay's first reply, consists of a single chain containing 3 to 5 strong links only. 5 if you really want to spell it out and be as helpful as possible, 3 if you want to be brief and assume a knowledgeable reader. What I would most prefer to do is present the short version, and reply to requests for more with a comprehensive lecture on the subject. Meanwhile, while I give more time to anyone trying to match the brevity of it, I want to place a code here, a key to my solution, for later reference if needed: 395361964959.

by **gurth** » Mon Nov 17, 2014 4:43 am

denis_berthier wrote:I'm eager to see your simpler solution

Code: Select all: 4 7 568 | 568 3 268 | 259 1 259 9 3 156 | 4 15 126 | 257 8 257 2 58 158 | 7 158 9 | 3 4 6 ------------------------+----------------------+--------------------- 358 2 578 | 9 6 4 | 78 35 1 358 6 578 | 1 578 e378 | 4 29 29 1 9 4 |a358 2 f378 | 678 356 378 ------------------------+----------------------+--------------------- 6 4 2 |b38 189 138 | 589 7 3589 7 1 9 |c368 4 5 | 268 236 238 58 58 3 | 2 79 d67 | 1 69 4

5r6c4=38r67c4-(38=6)r8c4-(6=7)r9c6-(7=38)r56c6-(38=5)r6c4 => 5r6c4; stte

by **daj95376** » Mon Nov 17, 2014 5:49 am

gurth wrote:5r6c4=38r67c4-(38=6)r8c4-(6=7)r9c6-(7=38)r56c6-(38=5)r6c4 => 5r6c4; stte

If you review eleven's solution, you'll see that he performs r6c4<>38 early ... and still needs several steps before stte.

I believe others encountered similar results and needed additonal steps as well.

My solver generated:

Code: Select all: (38=6)r78c4 - (6=7)r9c6 - (7=38)r56c6 => -38 r6c4,r7c6

But this is still insufficient to crack the puzzle.

_

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