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Almost no VH moves

 
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Thu May 13, 2010 6:49 pm    Post subject: Almost no VH moves Reply with quote

This seemed to get hard quickly for me! "Almost" no VH moves...

Code:
+-------+-------+-------+
| . . 1 | . . 2 | . . . |
| . . . | 7 . 9 | 1 . 5 |
| . 3 . | . . 4 | 7 6 . |
+-------+-------+-------+
| . . 6 | . . . | . 9 7 |
| . . . | 6 . 7 | . . . |
| 2 5 . | . . . | 6 . . |
+-------+-------+-------+
| . 7 5 | 8 . . | . 4 . |
| 8 . 3 | 2 . 6 | . . . |
| . . . | 9 . . | 3 . . |
+-------+-------+-------+


One solution

Quote:
"Almost" xy-wing(249) r9c3 pincers r3c3, r8c2
Either xy-wing or r8c2=1 (1=9)r8c9-(9=2)r3c9-(2=9)r3c3; r1c2<>9
xy-chain (6=8)r1c2-(8=1)r4c2-(1=3)r4c6-(3=1)r7c6-(1=3)r7c5-(3=6)r2c5; r1c5<>6
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri May 14, 2010 9:56 am    Post subject: Reply with quote

Ouch! For me this was a right b*****d and no mistake. Don't know where you found this one Peter but...damn!

[Eeek - edit - I've just looked as my answer again and realised I left out my first ALS - there are 2!! Apologies and thanks for the spot Ted. Smile It's what happens when you fire and forget because you've used the "Quote" then Color = white option !! ) Embarassed

Quote:
Sadly, for fans of the technique, there were no baphomets (that I could find) and I needed 4 steps and several coffees......

1a. ALS X = {1238} at r126c8; Z = {129} at r38c9; 2 = restricted common and 1 = common candidate so r89c8 and r56c9 <> 1

1b.ALS (my best move) X ={2389} at r12c8 r3c9; Z={5789} at r8c78 r9c8; 8= restricted common and 9 = common candidate so r1c7 r78c9 <> 9

2. XY Wing <469> vertex at r8c2; r9c1 r2c2 <> 4

3. XY Wing <249> vertex at r8c2; r9c2 <> 9

4. XY Chain on 3s pincers at r1c8 and r6c4


Last edited by Mogulmeister on Fri May 14, 2010 6:18 pm; edited 3 times in total
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peterj



Joined: 26 Mar 2010
Posts: 974
Location: London, UK

PostPosted: Fri May 14, 2010 1:46 pm    Post subject: Reply with quote

Nice ALS!

It's an Astraware diabolical (24000+ score - which is a hard one on that site). The quality of these puzzles is variable as their solver/setter goes from x-wings straight to forcing chains and even classes an xy-wing as a forcing chain. But sometimes there are some interesting ones where you can find an elegant solution avoiding the multiple forcing chains that their solution suggests.

I was pleased to find the 'almost xy-wing' because it was a whole lot of hurt otherwise!
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Mogulmeister



Joined: 03 May 2007
Posts: 1151

PostPosted: Fri May 14, 2010 1:58 pm    Post subject: Reply with quote

..yes that was a nice observation. Sooner or later the "almost" part is going to need a name..........bring back the "F-word" I say. Laughing

I was looking for ANPs but nothing too productive as yet. I will continue to play but I can see that this was well designed. Thanks.
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tlanglet



Joined: 17 Oct 2007
Posts: 2468
Location: Northern California Foothills

PostPosted: Fri May 14, 2010 2:27 pm    Post subject: Reply with quote

So far I have spotted two ANPs, but am still lost in the woods.

ANP(38=2)r12c8 - r3c9 = r3c3 - (2=4)r9c3 - (4=7)r9c7 - r9c8 = (7-5)r8c8 = (5)r5c8; r5c8<>38
ANP(69=2)r7c19 - (2=9)r3c9 - r1c79 = r1c2 - r8c2 = r7c1; r7c7<>9

Ted
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