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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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 Posted: Sat Oct 29, 2011 8:41 am Post subject: Free Press October 28, 3011 |
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Not yet started. Seems to be on the tough side.
| Code: | Puzzle: FP102811
+-------+-------+-------+
| . . . | . . . | 4 2 7 |
| . . . | . . 3 | 9 . . |
| 5 . . | 2 . 4 | . 1 . |
+-------+-------+-------+
| . . . | 9 1 . | 7 5 . |
| . . . | . . . | . . . |
| . 6 1 | . 4 2 | . . . |
+-------+-------+-------+
| . 2 . | . . 6 | . . 4 |
| . . 4 | 3 . . | . . . |
| 6 3 9 | . . . | . . 1 |
+-------+-------+-------+
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Play this puzzle online at the Daily Sudoku site
Keith |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Oct 29, 2011 9:54 am Post subject: |
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A tough one with a bug but I don't like bugs. | Code: | *-----------------------------------------------------------*
| 3 189 6 | 18 5 19 | 4 2 7 |
| 4 17-8 2 | 178 678 3 | 9 a68 5 |
| 5 789 e78 | 2 6789 4 | 36-8 1 3-8 |
|-------------------+-------------------+-------------------|
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 389 |
|-------------------+-------------------+-------------------|
| 18 2 d57 | 178 789 6 | 358 39 4 |
| 18 c57 4 | 3 27 19 | 256 b67 89 |
| 6 3 9 | 4 278 5 | 28 78 1 |
*-----------------------------------------------------------*
(8=6)r2c8-(6=7)r8c8-(7)r8c2=(7)r7c3-(7=8)r3c3 => r2c2,r3c79<>8
*--------------------------------------------------*
| 3 189 6 | 18 5 19 | 4 2 7 |
| 4 1-7 2 |*17 6 3 | 9 8 5 |
| 5 789 78 | 2 789 4 | 6 1 3 |
|----------------+----------------+----------------|
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 89 |
|----------------+----------------+----------------|
| 18 2 *57 |*178 789 6 | 358 39 4 |
| 18 *57 4 | 3 27 19 | 25 6 89 |
| 6 3 9 | 4 28 5 | 28 7 1 |
*--------------------------------------------------*
Turbot r2c2<>7
*--------------------------------------------------*
| 3 89 6 | 18 5 19 | 4 2 7 |
| 4 1 2 | 7 6 3 | 9 8 5 |
| 5 789 *78 | 2 *89 4 | 6 1 3 |
|----------------+----------------+----------------|
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 89 |
|----------------+----------------+----------------|
| 18 2 5-7 | 18 *79 6 | 35 39 4 |
| 18 57 4 | 3 27 19 | 25 6 89 |
| 6 3 9 | 4 28 5 | 28 7 1 |
*--------------------------------------------------*
xy wing 789 r7c3<>7 |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 29, 2011 11:03 am Post subject: |
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After basics: | Code: | +----------------+----------------+----------------+
| 3 189 6 | 18 5 19 | 4 2 7 |
| 4 178 2 | 178 678 3 | 9 68 5 |
| 5 789 78 | 2 6789 4 | 368 1 38 |
+----------------+----------------+----------------+
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 389 |
+----------------+----------------+----------------+
| 18 2 57 | 178 789 6 | 358 39 4 |
| 18 57 4 | 3 27 19 | 256 67 89 |
| 6 3 9 | 4 278 5 | 28 78 1 |
+----------------+----------------+----------------+ |
Edit: INCORRECT: W-wing 1-8; XY-wing 6-78; SS 7.
Keith
Last edited by keith on Sat Oct 29, 2011 2:32 pm; edited 1 time in total |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Oct 29, 2011 1:53 pm Post subject: |
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| keith wrote: | After basics: | Code: | +----------------+----------------+----------------+
| 3 189 6 | 18 5 19 | 4 2 7 |
| 4 178 2 | 178 678 3 | 9 68 5 |
| 5 789 78 | 2 6789 4 | 368 1 38 |
+----------------+----------------+----------------+
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 389 |
+----------------+----------------+----------------+
| 18 2 57 | 178 789 6 | 358 39 4 |
| 18 57 4 | 3 27 19 | 256 67 89 |
| 6 3 9 | 4 278 5 | 28 78 1 |
+----------------+----------------+----------------+ |
W-wing 1-8; XY-wing 6-78; SS 7.
Keith |
Help!  I don't see the w wing. Can you help? |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 29, 2011 2:31 pm Post subject: |
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Oops! Looks like I screwed up. 
Keith |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 29, 2011 2:55 pm Post subject: |
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How about this? | Code: | +----------------+----------------+----------------+
| 3 189 6 | 18 5 19 | 4 2 7 |
| 4 17-8 2 | 178 678 3 | 9 D68 5 |
| 5 789 A78 | 2 6789 4 |36-8 1 3-8 |
+----------------+----------------+----------------+
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | 38 39 389 |
+----------------+----------------+----------------+
| 18 2 57 | 178 789 6 | 358 39 4 |
| 18 B57 4 | 3 27 19 | 256 67 89 |
| 6 3 9 | 4 278 5 | 28 C78 1 |
+----------------+----------------+----------------+ |
M-wing: 7 in A forces 7 in B and C. AD are pincers on 8.
That leads to a SS 7, then either a BUG+1 or an XY-wing to finish it.
Keith |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Oct 29, 2011 3:56 pm Post subject: |
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| keith wrote: | | How about this? |
Keith,
I like it
Thanks |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 29, 2011 4:47 pm Post subject: |
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Dan,
Ah, I see my solution is the same as yours, except perhaps for identifying the M-wing by name.
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Oct 29, 2011 6:02 pm Post subject: |
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Skyscraper in c34; r2c2, r3c5<>7
Hidden UR (18); r1c2<>1, r2c4<>8
XY-Chain, 9 in r7c5 forces 7 in r3c3; r7c3<>7 |
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arkietech
Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA
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| Posted: Sat Oct 29, 2011 6:14 pm Post subject: |
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| keith wrote: | | Ah, I see my solution is the same as yours, except perhaps for identifying the M-wing by name. |
I have always had trouble with m wings and usually wind up with showing them as an AIC. I know Danny had a good study in m wings. I need some review.  |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Sat Oct 29, 2011 6:51 pm Post subject: |
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| arkietech wrote: | | keith wrote: | | Ah, I see my solution is the same as yours, except perhaps for identifying the M-wing by name. |
I have always had trouble with m wings and usually wind up with showing them as an AIC. I know Danny had a good study in m wings. I need some review. |
Dan,
Here's my recipe to look for them:
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=4366&start=21
In terms of my diagram above:
1. A may be 8, or
2. A may be 7, which forces 7 in C. Not 8 in C forces 8 in D.
A and D are pincers on 8.
For me, this recipe makes finding them no more difficult than finding a W-wing.
(Given my screw-up above, maybe I should reconsider that last statement!)
Keith |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sat Oct 29, 2011 7:15 pm Post subject: |
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Another three-stepper without a chain.
Hidden UR (38); r6c9<>3, r3c7<>8
Skyscraper; r2c2, r3c5<>7
XY-Wing (897); r7c3<>7 |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sun Oct 30, 2011 12:43 am Post subject: |
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Dan's chain is not the same as Keith's 4-SIS M-Wing; but it uses the same primary candidate and endpoint cells, so the eliminations are the same.
===== ===== ===== ===== =====
After basics and a Skyscraper, there's an interesting pairing on URs with diagonal bivalue cells.
| Code: | c34r7 Skyscraper <> 7 r2c2,r3c5
+-----------------------------------------------------+
| 3 *18+9 6 | *18 5 19 | 4 2 7 |
| 4 *18 2 | *18+7 678 3 | 9 68 5 |
| 5 789 78 | 2 689 4 | *38+6 1 *38 |
|-----------------+-----------------+-----------------|
| 2 4 3 | 9 1 8 | 7 5 6 |
| 9 58 58 | 6 3 7 | 1 4 2 |
| 7 6 1 | 5 4 2 | *38 39 *38+9 |
|-----------------+-----------------+-----------------|
| 18 2 57 | 178 789 6 | 358 39 4 |
| 18 57 4 | 3 27 19 | 256 67 89 |
| 6 3 9 | 4 278 5 | 28 78 1 |
+-----------------------------------------------------+
# 45 eliminations remain
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The <18> UR has an SL on <1> in [c2] and <8> in [r1] => r2c4<>18=7.
The <38> UR has an SL on <3> in [c9] and <8> in [r6] => r3c7<>38=6.
A BUG+1 (XY-Wing) follows. |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Oct 30, 2011 1:22 am Post subject: |
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| Quote: | The <18> UR has an SL on <1> in [c2] and <8> in [r1] => r2c4<>18=7.
The <38> UR has an SL on <3> in [c9] and <8> in [r6] => r3c7<>38=6. |
Danny, that's a good reminder for me and others to look more carefully for the strong links. In my solutions posted above I eliminated a 1 and 8 from the one UR and a 3 and 8 from the other. However, in neither case did I eliminate both candidates from one cell because I didn't check the SL's closely enough. |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Sun Oct 30, 2011 5:53 pm Post subject: |
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| Marty R. wrote: | Danny, that's a good reminder for me and others to look more carefully for the strong links. In my solutions posted above I eliminated a 1 and 8 from the one UR and a 3 and 8 from the other. However, in neither case did I eliminate both candidates from one cell because I didn't check the SL's closely enough.
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Hello Marty,
After I wrote UR routines to find UR Types 1-6, I wrote a UR routine to check for additional UR eliminations based on strong links associated with the UR cells and candidates. I continue to be amazed at the number of eliminations that last routine finds!!!
I've been tempted to make a list of the different "patterns" found this way, but RonK would simply point out that I'm relisting entries from the works of Mike Barker. And, RonK would be correct, except for the fact that I don't understand half of Mike Barker's descriptions. _  _
Regards, Danny |
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Marty R.
Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
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| Posted: Sun Oct 30, 2011 6:13 pm Post subject: |
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| Quote: | | ...would simply point out that I'm relisting entries... |
And the problem with re-listing is...?? |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Mon Oct 31, 2011 12:49 am Post subject: |
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| daj95376 wrote: |
I've been tempted to make a list of the different "patterns" found this way, but RonK would simply point out that I'm relisting entries from the works of Mike Barker. And, RonK would be correct, except for the fact that I don't understand half of Mike Barker's descriptions. _ _
Regards, Danny |
So,
Make a new list, and RonK can do the cross-reference to other lists, if he so wishes.
Keith |
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daj95376
Joined: 23 Aug 2008
Posts: 3854
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| Posted: Mon Oct 31, 2011 1:44 am Post subject: |
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Hmmm. Time to do some random rambling.
Rambling #1:
Not that long ago, RonK mentioned in another forum that he was considering posting examples of Mike Barker's UR patterns. That endeavour (British spelling) never went very far. I always wondered how much preparation he'd already done ... and if it was only for the more complex patterns.
Rambling #2:
I don't have a complete list of UR+SL patterns. I randomly review puzzle solutions and end up impressed by the UR+SL patterns that aren't obvious (to me).
For me to prepare a discussion on UR+SL patterns, I'd need to review many puzzles and make notes on the patterns present. I have Mike Barkers "zoo" collection of puzzles for URs -- along with a solution for most of them. I also have a collection of puzzles that have instances of UR+SL patterns. In any case, I'll need time to review these puzzles and prepare UR+SL pattern examples.
Rambling #3:
Let me see how far I get ... and how much RonK would also like to contribute.
Regards, Danny |
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keith
Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
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| Posted: Mon Oct 31, 2011 2:34 am Post subject: |
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| daj95376 wrote: | Hmmm. Time to do some random rambling.
Rambling #1:
Not that long ago, RonK mentioned in another forum that he was considering posting examples of Mike Barker's UR patterns. That endeavour (British spelling) never went very far. I always wondered how much preparation he'd already done ... and if it was only for the more complex patterns.
Rambling #2:
I don't have a complete list of UR+SL patterns. I randomly review puzzle solutions and end up impressed by the UR+SL patterns that aren't obvious (to me).
For me to prepare a discussion on UR+SL patterns, I'd need to review many puzzles and make notes on the patterns present. I have Mike Barkers "zoo" collection of puzzles for URs -- along with a solution for most of them. I also have a collection of puzzles that have instances of UR+SL patterns. In any case, I'll need time to review these puzzles and prepare UR+SL pattern examples.
Rambling #3:
Let me see how far I get ... and how much RonK would also like to contribute.
Regards, Danny |
Danny,
For what it's worth, I think someone should consider whether a revised classification of URs is a good idea.
And then, a catalog with examples would be nice to have.
Keith |
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ronk
Joined: 07 May 2006
Posts: 398
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| Posted: Mon Oct 31, 2011 3:25 am Post subject: |
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| daj95376 wrote: | | Not that long ago, RonK mentioned in another forum that he was considering posting examples of Mike Barker's UR patterns. That endeavour (British spelling) never went very far. I always wondered how much preparation he'd already done ... and if it was only for the more complex patterns. |
Not sure where I would have thought those examples were supposed to come from. While I have quite a few UR+SL patterns programmed, very few use Mike Barker's names. A fair amount of cross-referencing work would be required.
Perhaps I was thinking exemplars, but my "URs with hidden sets" file is almost empty. |
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