This document provides the solution to Weekly Extreme Str8ts Puzzle #47 from May 15-21, 2011. It notes that the puzzle has several long rows and columns and only two small compartments, making it well-suited for using Setti's rule. Key steps in the solution include using Setti's rule on the numbers 7 and 1 to eliminate possibilities. Applying the rule to 3 and 4 is optional. The puzzle is solved systematically by eliminating possibilities and filling in determined values.

1. Weekly Extreme Str8ts Puzzle #47 May 15 – May 21, 2011www.str8ts.comSolution bySlowThinker

2. Start positionExtreme Str8ts #47 has several rows and columns that span 9 cells and does only have two compart-ments smaller than 3 cells.This will be beneficial for solving this puzzle using Setti’s rule, as small compartments usually lead to “undecided” rows and columns when applying Setti’s rule.

3. Solving…F6=4cG2=5hJ2=6H2=4J3=7

4. Solving…J1=9hH1=6sJ8=4sA3=2s

5. Solving…D3=3hD4=5D7=2J6=2sC5=2s

6. Solving…G6=9sG8=2sH8=3c

7. Optional:Setti’s rule on 3As you can see there has to be a 3 in every column There has to be a 3 in row E as well, thus we can remove 89 from row E(Note: This step is not necessary to solve the puzzle.)Border colors:green: number has to be in this row/column,yellow: number may be there, red: number is not there

8. Optional:Setti’s rule on 4Same is true for number 4 and column 9  we can therefore remove 89 from column 9(Note: This step is not necessary to solve the puzzle.)D9=6S4A7=6s

9. Setti’s rule on 7There are 8 columns that have a 7 (all except column 2), so there must be 8 rows that contain a 7 as wellF1=7S7G1=8G9=3G5=7J9=1

10. Solving…J7=3cF7=1F5=3E4=3sE3=4s

11. Solving…E5=6sC3=8B3=6Note: we could remove 8 remove from H5, because 8 must be in H67, as otherwise we would violate the uniqueness constraint with EH67. But let’s continue without this…

12. Setti’s rule on 1As we can see there are two columns that do not contain a 1  row A cannot contain a 1 either.Furthermore, column 5 must contain a 1, as seven rows contain a 1 A2=3S1A4=4S1A1=5B1=4C1=3C2=1

13. Solving…A9=7B9=5C9=4A6=8A8=9C8=7B8=8

14. Finishing…B5=1C4=9, B4=7, B7=9C7=5, E7=7, E6=5H4=1, H5=5H6=7H7=8

15. DoneUsing Setti’s rule two times(*) (on 7 and 1,) this puzzle was quite easy.If you like, try solving this puzzle without using Setti’s rule. It’s possible, but more difficult.(*) Applying Setti’s rule on 3 and 4 is not necessary to solve this puzzle

16. GlossaryLetters appended to steps indicate the last strategy used, just before filling in a field:No letter … number was last candidate in fields … single (last) candidate for that number in compartmentc … compartment range checkd … stranded (unreachable/impossible) digits removedh … high/low range check across compartmentsp/t/q … naked pair / naked triple / naked quadrupleph/th/qh … hidden pair / hidden triple / hidden quadruplex … X-wing (2 rows / 2 columns)w … Swordfish (3 rows / 3 columns)j … Jellyfish (4 rows / 4 columns)L … large gap fieldSx … Setti’s rule (count the numbers rule) – ‘x’ is the analysed numberu … unique rectangley … Y-Wing or XY-chains

17. Weekly Extreme Str8ts Puzzle #47www.str8ts.comSolution by SlowThinkerNote: there are other (maybe easier) ways to solve this puzzle.