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Ron Moore
Addict

Joined: 13 Aug 2006
Posts: 72
Location: New Mexico

Posted: Thu Dec 28, 2006 6:12 pm    Post subject: 28 Dec 2006 Nightmare: Quick Solution

This is the position in the 28 Dec 2006 Nightmare, after initial eliminations from basic techniques:
 Code: .------------------.-------------------.------------------. | 1237  4    *236  | 9     56     8    | 567   27    137  | | 237  *267   9    | 56    4      1    | 5678  278   378  | | 5    *16    8    | 3     2      7    | 69    4     19   | :------------------+-------------------+------------------: | 18   *156   4    | 56    13567  35   | 78    9     2    | |-289  *256  *26   |-24    5679  -2459 | 3     1     78   | | 1-29  3     7    | 8     19     29   | 4     56    56   | :------------------+-------------------+------------------: | 4     8     1    | 7     59     6    | 2     3     59   | | 6     27    5    | 1     389    2349 | 789   78    4789 | | 237   9     23   | 24    58     245  | 1     5678  45678| '------------------'-------------------'------------------'

After eliminations from the following chain (cells marked with "*" in the diagram), the solution is completed with singles only:
(2=6)r5c3 - (6)r1c3 = (6)r2c2 - (6=152)r345c2 => r5c146, r6c1 <> 2
Myth Jellies
Hooked

Joined: 04 Apr 2006
Posts: 42

 Posted: Fri Jan 05, 2007 1:16 am    Post subject: Hate to spoil your fun, Ron; but if your grid is correct, there is no obvious (6)r1c3 = (6)r2c2 strong link. The 6 in r3c2 messes you up. There is a nice little 56-UR in r69c89 which can only be escaped via the 5 in r7c9. Might as well hit the low hanging fruit.
Ron Moore
Addict

Joined: 13 Aug 2006
Posts: 72
Location: New Mexico

 Posted: Mon Jan 08, 2007 12:57 am    Post subject: Guilty as Charged Ugh! No excuse for that. I think I had one too many (puzzles at one stretch).
rcbroughton
Expert

Joined: 15 Nov 2006
Posts: 143
Location: London

 Posted: Tue Jan 09, 2007 7:16 pm    Post subject: Once you do the simple eliminations from the UR, there is a strong chain on 7 at r9c9->r9c1->r8c2->r2c2 that eliminates 7 from r2c9 followed by a strong/weak chain on value 2 at r5c2->r5c4->r9c4->r8c6->r8c2 eliminating 2 from r5c2 after another cople of simple steps there's a strong/weak chain on 5 at r1c5->r2c4->r2c7->r3c7->r3c9->r3c2->r5c2 removing 5 from r5c5 There are then a couple of real tricky to spot chains r5c9->r4c7->r4c1->r4c2->r3c2->r3c9->r3c7->r2c7->r2c4->r1c5->r9c5 removing 8 from r9c9 then (1)r1c1->(1)r1c9->(3)r1c9->(3)r2c9->(8)r2c9->(8)r2c8->(2)r2c8->(2)r1c8 removing 2 from r1c1 and 1 from r1c8 then (1)r1c1->(1)r1c9->(3)r1c9->(3)r2c9->(8)r2c9->(8)r2c8->(8)r8c8->(7)r8c8->(7)r8c2->(7)r2c2 removing 7 from r1c1 and 1 from r2c2 finally r1c1->r3c2->r4c2->r4c1->r4c7->r5c9->r2c9 3 from r1c9 r2c1 after that, it's singles
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