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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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 Posted: Sun May 04, 2008 2:23 pm Post subject: ER heaven |
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M5566984 (39) | Code: |
+-------------+------------+--------------+
| 3 8 1 | 679 2 5 | 679 69 4 |
| 67 479 5 | 4679 1 8 | 2 3 679 |
| 2 479 679 | 4679 69 3 | 5 1 8 |
+-------------+------------+--------------+
| 9 1 3 | 5 4 6 | 8 7 2 |
| 5 27 27 | 8 3 1 | 69 4 69 |
| 8 6 4 | 2 7 9 | 13 5 13 |
+-------------+------------+--------------+
| 1 2359 269 | 69 569 7 | 4 8 369 |
| 67 379 679 | 1 8 4 | 3679 2 5 |
| 4 579 8 | 3 569 2 | 1679 69 1679 |
+-------------+------------+--------------+
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Play this puzzle online
There have been some v. difficult puzzles posted recently. Here's a more middle-of-the-road one.
ERs + URs + remote pairs for me - about half a dozen non-basic moves. No doubt other, maybe quicker ways to do it. |
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nataraj
Joined: 03 Aug 2007
Posts: 1048
Location: near Vienna, Austria
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| Posted: Sun May 04, 2008 6:12 pm Post subject: |
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Seems I am not the ER type.
Did not find any ERs, but ...
a skyscraper (7) cols 1 and 9 got me here:
| Code: |
+--------------------------+--------------------------+--------------------------+
| 3 8 1 | 679 2 5 | 679 69 4 |
| 67 479 5 | 4679 1 8 | 2 3 679 |
| 2 479 679 | 4679 69 3 | 5 1 8 |
+--------------------------+--------------------------+--------------------------+
| 9 1 3 | 5 4 6 | 8 7 2 |
| 5 27 27 | 8 3 1 | 69 4 69 |
| 8 6 4 | 2 7 9 | 13 5 13 |
+--------------------------+--------------------------+--------------------------+
| 1 2359 269 | 69 569 7 | 4 8 369 |
| 67 379 679 | 1 8 4 | 369 2 5 |
| 4 59 8 | 3 569 2 | 17 69 17 |
+--------------------------+--------------------------+--------------------------+
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I used a UR argument 59 r79c25 (sorry I still do not know which type it is. I used the x-wing on 5 and reasoned that if r7c5=9 then r7c2=5, r9c2=9, r9c5=5 which is DP, thus r7c5 cannot be 9) to remove 9 from r7c5.
From there:
skyscraper 9 cols 5,8
more coloring on 9 later to remove 9 from r9c2, 9:-r2c2=r2c4-r3c5=r9c5-
(multi-)coloring on 6 (skyscraper et al.)
All in all, but for the UR, a very colorful solution  |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Mon May 05, 2008 3:50 am Post subject: |
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I used the same UR, which seems to be necessary to solve the puzzle. I know some people know all the UR types, but there are so many that I don't know them beyond 4 either.
One of the ERs does the 9 in r9c2, based on c5 (after the UR elimination). I don't know whether ERs are ever necessary - you can obviously do at least most of them by colouring etc. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Mon May 05, 2008 4:27 am Post subject: |
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| Code: | +--------------------------+--------------------------+--------------------------+
| 3 8 1 | 679 2 5 | 679 69 4 |
| 67 479 5 | 4679 1 8 | 2 3 679 |
| 2 479 679 | 4679 69 3 | 5 1 8 |
+--------------------------+--------------------------+--------------------------+
| 9 1 3 | 5 4 6 | 8 7 2 |
| 5 27 27 | 8 3 1 | 69 4 69 |
| 8 6 4 | 2 7 9 | 13 5 13 |
+--------------------------+--------------------------+--------------------------+
| 1 2359 269 | 69 569 7 | 4 8 369 |
| 67 379 679 | 1 8 4 | 369 2 5 |
| 4 59 8 | 3 *569 2 | 17 *69 17 |
+--------------------------+--------------------------+--------------------------+ |
this is nataraj's grid (above)
the w-wing is marked on the pair {69} in r3c5 and r1c8, strong link on 6 in row 6, removes the 9 in r1c4,
leaves this UR on {4,9} which removes the 9's in r3c24 ( below)
| Code: | .------------------.------------------.------------------.
| 3 8 1 | 67 2 5 | 679 69 4 |
| 67 #49 5 |#49 1 8 | 2 3 67 |
| 2 #479 679 |#4679 69 3 | 5 1 8 |
:------------------+------------------+------------------:
| 9 1 3 | 5 4 6 | 8 7 2 |
| 5 27 27 | 8 3 1 | 69 4 69 |
| 8 6 4 | 2 7 9 | 13 5 13 |
:------------------+------------------+------------------:
| 1 2359 269 | 69 569 7 | 4 8 369 |
| 67 379 679 | 1 8 4 | 369 2 5 |
| 4 59 8 | 3 569 2 | 17 69 17 |
'------------------'------------------'------------------' |
coloring on 9's eliminates a 9 in r7c3
xy-wing on {2,6,7} pivot in r7c3 removes 7 in r8c3
this is where it gets shady for me. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Mon May 05, 2008 4:41 am Post subject: |
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| Quote: | | this is where it gets shady for me. |
I think you're almost there. It's certainly easier if you do the UR that Nataraj reported, which kills the 9 in r7c5. |
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storm_norm
Joined: 18 Oct 2007
Posts: 1741
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| Posted: Mon May 05, 2008 4:45 am Post subject: |
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ok, those x-wing URs aren't my friends  |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon May 05, 2008 4:12 pm Post subject: |
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I wouldn't call it ER Heaven. I like ERs but could only find one here for <7> using C1 and Box 3. The candidates for <3> cannot form an ER (you need the candidates in four aligned boxes). Nos <1> <2> <4> & <5> only have four candidates (need at least two in a box for an ER). There are no <8>s ...and for <6> & <9> there are only rows with two candidates - and neither lines up with an ER.
I may have missed one - but I don't think so.
Craig |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Mon May 05, 2008 9:20 pm Post subject: |
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| Quote: | | I like ERs but could only find one here for <7> |
I think it depends (as many puzzles do) on the order in which it's done.
I started with the same ER in <7> as you.
Then the UR that Nataraj explained removes the 9 from r7c5. That leaves | Code: | +--------------------------+--------------------------+--------------------------+
| 3 8 1 | 679 2 5 | 679 69* 4 |
| 67 479 5 | 4679 1 8 | 2 3 679 |
| 2 479 679 | 4679 69 3 | 5 1 8 |
+--------------------------+--------------------------+--------------------------+
| 9 1 3 | 5 4 6 | 8 7 2 |
| 5 27 27 | 8 3 1 | 69 4 69 |
| 8 6 4 | 2 7 9 | 13 5 13 |
+--------------------------+--------------------------+--------------------------+
| 1 2359 269 | 69* 56 7 | 4 8 369 |
| 67 379 679 | 1 8 4 | 369 2 5 |
| 4 59 8 | 3 569* 2 | 17 69* 17 |
+--------------------------+--------------------------+--------------------------+ |
Now there's an ER in <9> based on c5 that removes 9 from r9c2.
That gives remote pairs <69> *d, that cleans up r1c4.
Now when r2 is cleaned up, r2c24 are both 49, & so we can do a type 4 UR to remove the 9s from r3c24. Now there are only two 9s in r3, in c35, and an ER based on them removes the 9 from r7c3 |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Mon May 05, 2008 10:04 pm Post subject: |
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| Victor: I still couldn't find the subsequent ER on <9> but I'm sure you are correct. However - still feel that doing it twice aint really Heaven. |
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Victor
Joined: 29 Sep 2005
Posts: 207
Location: NI
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| Posted: Tue May 06, 2008 8:12 pm Post subject: |
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| Did use 3 ERs (honest!), but I'll cave in & agree that that doesn't qualify as 'heaven'. Next time I post a puzzle with lots of the same technique I won't call it "*** heaven" unless it's got at least 5 of the ***. |
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cgordon
Joined: 04 May 2007
Posts: 769
Location: ontario, canada
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| Posted: Tue May 06, 2008 8:23 pm Post subject: |
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| Quote: | | Next time I post a puzzle with lots of the same technique I won't call it "*** heaven" unless it's got at least 5 of the ***. |
I'll cut you some slack - call it after 4 |
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