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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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 Posted: Tue Nov 20, 2007 1:49 am Post subject: And yet another |
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| Code: |
+-------+-------+-------+
| 5 4 9 | 3 . 7 | . . . |
| 6 . . | . 5 9 | . 7 4 |
| . 7 . | . . 4 | 9 . 5 |
+-------+-------+-------+
| 1 6 7 | . 3 . | . . 9 |
| . . . | 2 9 6 | 7 . . |
| . 9 . | . 7 1 | 5 . 6 |
+-------+-------+-------+
| 9 . 8 | 7 4 2 | . . . |
| 4 2 . | . 1 . | . 9 7 |
| 7 . . | 9 . 3 | 4 . . |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Tue Nov 20, 2007 2:34 am Post subject: Re: And yet another |
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I had to use a 7 step xy-chain to eliminate 5 from R5C3.
There must be a neater solution.
Earl |
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Earl
Joined: 30 May 2007
Posts: 677
Location: Victoria, KS
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| Posted: Tue Nov 20, 2007 2:40 am Post subject: Re: And yet another |
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Here's the grid after basic steps.
Earl
| Code: |
+-------------+------------+----------------+
| 5 4 9 | 3 268 7 | 1268 1268 128 |
| 6 138 123 | 18 5 9 | 1238 7 4 |
| 238 7 123 | 168 268 4 | 9 12368 5 |
+-------------+------------+----------------+
| 1 6 7 | 458 3 58 | 28 248 9 |
| 38 358 345 | 2 9 6 | 7 1348 138 |
| 238 9 234 | 48 7 1 | 5 2348 6 |
+-------------+------------+----------------+
| 9 135 8 | 7 4 2 | 136 1356 13 |
| 4 2 356 | 568 1 58 | 368 9 7 |
| 7 15 156 | 9 68 3 | 4 12568 128 |
+-------------+------------+----------------+
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Play this puzzle online at the Daily Sudoku site |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Tue Nov 20, 2007 2:59 am Post subject: |
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Earl,
Your grid isn't simplified fully. You have Locked Candidates in several Boxes. After that, there is at least one Locked Set. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Tue Nov 20, 2007 3:29 am Post subject: |
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| Code: | ------------------------------------------------------------------------------|
| 5 4 9 | 3 268 7 | 16 1268 128 |
| 6 138@ 123@ | 18 5 9 | 238@ 7 4 |
| 238 7 12-3 | 168 268 4 | 9 2368 5 |
------------------------------------------------------------------------------|
| 1 6 7 | 45-8# 3 58# | 28 248 9 |
| 38 358 345 | 2 9 6 | 7 1348 138 |
| 238 9 234 | 48 7 1 | 5 348 6 |
------------------------------------------------------------------------------|
| 9 153 8 | 7 4 2 | 16 1356 13 |
| 4 2 36@ | 56-8# 1 58# | 38@ 9 7 |
| 7 15 156 | 9 68 3 | 4 1258 128 |
------------------------------------------------------------------------------|
the @ is a finned x-wing on the 3's r3c3 is not a 3
the # is a UR and eliminates some 8's in c4 |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Tue Nov 20, 2007 3:32 am Post subject: |
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After an ER (<3>) and several X-Wings (<3> and <8>), I found a nice example of coloring from W-Wing Pincers:
| Code: | +-------------+-----------+--------------+
| 5 4 9 | 3 268 7 | 16 1-268 28 |
| 6 8 r23 | 1 5 9 |g23 7 4 |
|g23 7 1 | 68 268 4 | 9 -2368 5 |
+-------------+-----------+--------------+
| 1 6 7 | 45 3 58 | 28 R24@ 9 |
| 8 35 45 | 2 9 6 | 7 14 13 |
|r23 9 g24@ | 48 7 1 | 5 348 6 |
+-------------+-----------+--------------+
| 9 135 8 | 7 4 2 | 16 156 13 |
| 4 2 36 | 56 1 58 | 38 9 7 |
| 7 15 56 | 9 68 3 | 4 1258 28 |
+-------------+-----------+--------------+ |
The otherwise useless {24} W-Wing (strong link in C4) is marked @. Coloring from R6C3 removes the <2>s in Box 3 as shown. But, there's more:
| Code: | +-------------+-----------+--------------+
| 5 4 9 | 3 268 7 | 16 168 28 |
| 6 8 G23 | 1 5 9 |R23 7 4 |
|R23 7 1 | 68 268 4 | 9 368 5 |
+-------------+-----------+--------------+
| 1 6 7 | 45 3 58 |G28 R24@ 9 |
| 8 35 45 | 2 9 6 | 7 14 13 |
|-23 9 g24@ | 48 7 1 | 5 348 6 |
+-------------+-----------+--------------+
| 9 135 8 | 7 4 2 | 16 156 13 |
| 4 2 36 | 56 1 58 | 38 9 7 |
| 7 15 56 | 9 68 3 | 4 1258 28 |
+-------------+-----------+--------------+ |
Coloring from the other Pincer removes <2> at R6C1 and solves the puzzle. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Tue Nov 20, 2007 3:36 am Post subject: |
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storm_norm,
If you use the ER in Box 7 with the link in C7, the <3> in R2C2 is eliminated. The resulting X-Wings (there are 3 involving those <3>s) eliminate many of the other <3>s. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Tue Nov 20, 2007 3:42 am Post subject: |
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| yes, I love those x-wings. |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Tue Nov 20, 2007 3:44 am Post subject: |
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| Yeah... it's sorta X-Wings galore! |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Tue Nov 20, 2007 3:46 am Post subject: |
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| I was trying to go back to the 3's, i am sure there is a bigger fish in there, maybe sashimi. I think some of the 3's are implied tho. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Tue Nov 20, 2007 3:58 am Post subject: |
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| Code: | +-------------+-----------+--------------+
| 5 4 9 | 3 268 7 | 16 168 28 |
| 6 8 G23* | 1 5 9 |R23 7 4 |
|R23 7 1 | 68* 268 4 | 9 368 5 |
+-------------+-----------+--------------+
| 1 6 7 | 45 3 58 |G28 R24@ 9 |
| 8 35 45 | 2 9 6 | 7 14 13 |
|-23 9 g24* | 48* 7 1 | 5 348 6 |
+-------------+-----------+--------------+
| 9 135 8 | 7 4 2 | 16 156 13 |
| 4 2 36* | 5-6 1 58 | 38 9 7 |
| 7 15 56 | 9 68 3 | 4 1258 28 |
+-------------+-----------+--------------+ |
my * is another xy chain start at r8c3 end at r8c4 can't be a 6 |
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Asellus
Joined: 05 Jun 2007
Posts: 865
Location: Sonoma County, CA, USA
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| Posted: Tue Nov 20, 2007 4:39 am Post subject: |
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At the point where I show the W-Wing coloring, there are many ways to solve the puzzle. The simplest is probably the X-Wing on <8> in C67.
I, also, wondered more about those <3>s. Nothing that I can find works as easily as that ER for clearing them out. However, there are some finned fish with transported fins possible. We start with your Finned X-Wing to remove <3> from R3C3. Then:
| Code: | +--------------+------------+----------------+
| 5 4 9 | 3 268 7 |e16 1268 e128 |
| 6 f138 123 | 18 5 9 | 238 7 4 |
| 238 7 12 | 168 268 4 |e9 2368 e5 |
+--------------+------------+----------------+
| 1 6 7 | 458 3 58 | 28 248 9 |
| 38 x358 345 | 2 9 6 | 7 1-348 x138 |
| 238 9 234 | 48 7 1 | 5 348 6 |
+--------------+------------+----------------+
| 9 x135 8 | 7 4 2 | 16 1-356 x13 |
| 4 2 36 | 568 1 58 | 38 9 7 |
| 7 15 156 | 9 68 3 | 4 1258 128 |
+--------------+------------+----------------+ |
The remote fin of the Finned X-Wing in C29 can be transported to C8 via the strong link or ER in Box 3, eliminating the <3>s shown. Then, a conventional Finned X-Wing in C18 eliminates <3> at R6C3. That results in a C36 X-Wing removing <3> from R5C1.
We're almost there. The last step is the fun one: another transported fin, this time in C37:
| Code: | +---------------+------------+----------------+
| 5 4 9 | 3 268 7 |e16 1268 e128 |
| 6 1-38 x123 | 18 5 9 |x238 7 4 |
| 238 7 12 | 168 268 4 |e9 2368 e5 |
+---------------+------------+----------------+
| 1 6 7 | 458 3 58 |e28 248 e9 |
| 38 358 f345 | 2 9 6 | 7 148 138 |
| 238 9 24 | 48 7 1 |e5 348 e6 |
+---------------+------------+----------------+
| 9 135 8 | 7 4 2 | 16 156 13 |
| 4 2 x36 | 568 1 58 |x38 9 7 |
| 7 15 156 | 9 68 3 | 4 1258 128 |
+---------------+------------+----------------+ |
There are a couple of ways to transport the fin. The simplest is via the strong link in Box 7. However, you could also use the two ERs (or two strong links) in Boxes 6 and 3. After that, the R28 X-Wing brings us to the same place as the previous (and simpler) ER followed by cascading X-Wings.
This route is sort of the "backward" way to do it. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Tue Nov 20, 2007 1:41 pm Post subject: |
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In this position my unwritten program e.g. could tell me, that the only possible placements in boxes 6 and 9 are as shown
(in this case "external" strong links are 2 in r4, 1 in r6, 8 in c7, 58 in c8 ).
| Code: | *--------------------------------------------*
| 5 4 9 | 3 26 7 | 16 126 8 |
| 6 8 23 | 1 5 9 | 23 7 4 |
| 23 7 1 | 68 268 4 | 9 236 5 |
|--------------+--------------+--------------| ---------------|
| 1 6 7 | 45 3 58 | 28 24 9 | | 8 2 9 |
| 8 35 45 | 2 9 6 | 7 14 13 | | 7 1 3 |
| 23 9 24 | 48 7 1 | 5 348 6 | | 5 4 6 |
|--------------+--------------+--------------| ---------------|
| 9 135 8 | 7 4 2 | 16 156 13 | | 6 5 1 |
| 4 2 36 | 56 1 58 | 38 9 7 | | 3 9 7 |
| 7 15 56 | 9 68 3 | 4 158 2 | | 4 8 2 |
*--------------------------------------------* ---------------|
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Then i could look why and e.g. see
an xy-chain
r5c8=4 => r4c8=2 => r4c7=8 => r8c7=3 => r7c9=1 (r5c9,r7c8<>1)
or a contradiction chain
r8c8=1 => r7c9=3
r8c8=1 => r7c8=8 => r5c9=3
or an ALS
A={12348} in r5c78 and r6c89, B={13568} in r7c789 and r8c8, x=3, z=8 => r6c8<>8
Not a great point here (i would prefer about Asellus' solution), but of course it would be more interesting with harder grids and more boxes (in the hardest even 1 impossible candidate in a reduced number of boxes is interesting).
Ok, its said and someone will implement it, earlier or later  |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Wed Nov 21, 2007 8:41 am Post subject: |
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| keith wrote: | | Is your proposal perhaps something like Trebor's Tables? Forgive me if I do not understand. |
No, as far as i remember Trebor's tables are a systematic method to find (multiple) forcing chains (which i would not recommend to do manually).
What i had in mind is just a tool using a brute force programming algorithm (like the programs that just solve puzzles with t&e in very short time), that shows possible eliminations, when not the whole puzzle, but only a restricted number of boxes is looked at. Something like "if you look at boxes 1, 7 and 8, you can find that 5 can be eliminated from r8c5".
So it might be a help to get new ideas or improve solving methods. Also it could be a help to classify (rate) hard puzzles. E.g. puzzles, that can be solved, when looking at only 2 boxes at a time, cannot be extremely hard. |
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re'born
Joined: 28 Oct 2007
Posts: 80
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| Posted: Wed Nov 21, 2007 1:10 pm Post subject: |
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| ravel wrote: | | keith wrote: | | Is your proposal perhaps something like Trebor's Tables? Forgive me if I do not understand. |
No, as far as i remember Trebor's tables are a systematic method to find (multiple) forcing chains (which i would not recommend to do manually).
What i had in mind is just a tool using a brute force programming algorithm (like the programs that just solve puzzles with t&e in very short time), that shows possible eliminations, when not the whole puzzle, but only a restricted number of boxes is looked at. Something like "if you look at boxes 1, 7 and 8, you can find that 5 can be eliminated from r8c5".
So it might be a help to get new ideas or improve solving methods. Also it could be a help to classify (rate) hard puzzles. E.g. puzzles, that can be solved, when looking at only 2 boxes at a time, cannot be extremely hard. |
Actually, it reminds me of 'Sherlocking'. |
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ravel
Joined: 21 Apr 2006
Posts: 536
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| Posted: Wed Nov 21, 2007 5:18 pm Post subject: |
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Yes, seems to be a similar idea. I dont think more about it - i know too good, that if i start it, i will find 100 improvements to make ...
Have you seen MJ's new technique ? Funnily i could apply it in the helpme puzzle also posted today:
| Code: | *-----------*
|5..|3.4|..8|
|...|5.9|...|
|..4|.8.|...|
|---+---+---|
|..2|.9.|.3.|
|..7|...|4..|
|.1.|.2.|69.|
|---+---+---|
|...|.4.|2..|
|...|6.7|...|
|8..|2.3|..5|
*-----------*
*-------------------------------------------------*
| 5 2679 169 | 3 67 4 | 1-79 1267 8 |
| 1267 8 136 | 5 67 9 | 13-7 12467 B46 |
| 679 3679 4 | 1 8 2 | 5 B67 369 |
|------------------+-----------+------------------|
| 4 5 2 | 7 9 6 | 8 3 1 |
| 69 69 7 | 8 3 1 | 4 5 2 |
| 3 1 8 | 4 2 5 | 6 9 7 |
|------------------+-----------+------------------|
| 167 367 5 | 9 4 8 | 2 16-7 36 |
| 129 249 139 | 6 5 7 | 139 8 A49 |
| 8 4679 69 | 2 1 3 |A79 467 5 |
*-------------------------------------------------*
ALS
*-------------------------------------------------*
| 5 2679 169 | 3 67 4 | 19 1267 8 |
|#1267 8 @13A6 | 5 67 9 |@1A3 12467 46 |
| 679 3679 4 | 1 8 2 | 5 67 369 |
|------------------+-----------+------------------|
| 4 5 2 | 7 9 6 | 8 3 1 |
| 69 69 7 | 8 3 1 | 4 5 2 |
| 3 1 8 | 4 2 5 | 6 9 7 |
|------------------+-----------+------------------|
|#1b67 367 5 | 9 4 8 | 2 @1B6 36 |
|#12 24 #13a | 6 5 7 |#1b39 8 49 |
| 8 469 69 | 2 1 3 | 7 46 5 |
*-------------------------------------------------*
r8c3<>1, r2c1<>1 |
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re'born
Joined: 28 Oct 2007
Posts: 80
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| Posted: Thu Nov 22, 2007 2:55 pm Post subject: |
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| ravel wrote: | Yes, seems to be a similar idea. I dont think more about it - i know too good, that if i start it, i will find 100 improvements to make ...
Have you seen MJ's new technique ? Funnily i could apply it in the helpme puzzle also posted today:
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That's really cool. A couple of weeks ago, Mike Barker had translated some of champagne's tagging rules for us on the Eureka forum and I figured it would only be a matter of time before someone (read: Myth) would find a pattern that even I could find. |
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