Solution to the weekly extreme Str8ts puzzle #57 from www.str8ts.com

1. Weekly Extreme Str8ts Puzzle #57 July 24 – July 30, 2011www.str8ts.com Solution bySlowThinker

2. Start position Extreme Str8ts #57 has a good mix of different sized compartments. As it turns out, we need to look for many singles, to solve this puzzle. See my strategy slides for more info: http://slideshare.net/SlowThinker/str8ts-basic-and-advanced-strategies

3. Solving… B8=3c B9=2c A9=4c C9=3c A4=2c J5=8c

4. Solving… A7=5c A8=6c C3=7h B3=6c

5. Solving… B4=8s C4=4c C7=2 After this C2=19, a large gap pair, which means we can remove 19 from all other cells in column 2.

6. Setti’s rule on 1 3 columns do not contain a 1  three rows must not contain a 1 either  no 1 in row F and row J. 6 rows contain a 1  6 columns must too  there’s a 1 in columns 1, 2, and 8.

7. Setti’s rule on 1Result Due to range checks, we can remove 4 from GHJ1 and 9s from columns 2 and 8. C2=1S1 C8=8 C6=9 F8=7

8. Solving… From here on it is easy. Many singles though. F9=8h D5=2s F5=5 D8=1s D7=4p E7=3

9. Solving… B2=5s E3=2s F3=3 F4=6 F2=2

10. Solving… H3=1 H2=3 H1=2 J1=3 G1=1 J2=4 J3=5

11. Solving… J9=9 G3=4 E5=1s E1=9s B1=7c D1=6 D2=7

12. Solving… G2=6 E8=4s H8=5 H5=4s B5=9 G5=7

13. Solving… G9=5 G4=3 D4=5 D6=3 E4=7

14. Solving… G6=8 G7=9 H6=6 E6=5 E9=6 H9=7 H7=8

15. Solution This puzzle was not too difficult: only a single application of Setti’s rule, no other advanced strategies were necessary.

16. Glossary Letters appended to steps indicate the last strategy used, just before filling in a field: No letter … number was last candidate in field s … single (last) candidate for that number in compartment c … compartment range check d … stranded (unreachable/impossible) digits removed h … high/low range check across compartments p/t/q … naked pair / naked triple / naked quadruple ph/th/qh … hidden pair / hidden triple / hidden quadruple x … X-wing (2 rows / 2 columns) w … Swordfish (3 rows / 3 columns) j … Jellyfish (4 rows / 4 columns) L … large gap field Sx … Setti’s rule (count the numbers rule) – ‘x’ is the analysed number u … unique rectangle y … Y-Wing or XY-chains

17. Weekly Extreme Str8ts Puzzle #57www.str8ts.com Solution by SlowThinker Note: there are other (maybe easier) ways to solve this puzzle. View & download my strategy slides from: http://slideshare.net/SlowThinker/str8ts-basic-and-advanced-strategies or from Google Docs: http://is.gd/slowthinker_str8ts_strategy