This document summarizes the solution to a Diabolic Str8ts puzzle. It begins by describing the starting position and notes that ordinary strategies are not enough. It then outlines the steps taken, including applying Setti's rule on digits like 7 and 8, using techniques like X-wing and naked triples. Testing different possibilities leads to deducing values like J3=6 and eventually the full solution. Key links between cells are discovered and tested throughout the solving process.

1. Diabolic Str8ts Puzzle #1Solution & puzzle bySlowThinker

2. Start positionWith the diabolic str8ts series, I try to push the boundaries a bit. Ordinary strategies are not enough to solve these puzzles.

3. Solving…After applying the basic techniques, we arrive at the position on the right.In D7 and E7 9 is a stranded digit, as D7 contains the only 7 and E7 the only 8 in ABCDE7 E9=9dD5=9s

4. Split unique URHJ7 is a split compartment: either it is 234 or it is 789. But in the upper range it would form a unique rectangle with HJ6 to avoid the UR J7 must not be 78 J7=2349H7=348

5. Setti on 7There’s a 7 in every row, therefore there must be a 7 in every column too:D7=7S7In column 2 we can only deduce that one of B2 and J2 must contain a 7.

6. Setti on 8Row C does not contain an 8  at least one column must not have an 8 either  column 4 is the only possible column FGHJ4=4567S8D4=2hA4=9h

7. X-Wing & SettiAgain omitting the basic elimination steps, we arrive at this position:There’s an X-wing (marked green) on 3 that removes the 3 from E3 (marked red).Applying Setti’s rule on 4, we find that every row must have a 4  F1 != 9

8. Setti’s rule on 6& an easy testB1 is the only 6 in row B. If there’s no 6 there, there’s also no 6 in F2 and J2. What if B1=7?B1=7  F2=4S6but also:B1=7  C1=6  F1=4Hence: B1!=7  B2=7Note that we can remove 6 from J2 with very similar logic.

9. AnalysisDue to Setti on 6 we have a link between B1 and F2. There’s also a link between G1 and J7, because of Setti on 2 (marked border).We also have the green cells, which are mostly about 234 and the yellow area mostly about 689.At the intersection: J3

10. Testing J3=2So let us test J3=2, because it has an impact on J7:J3=2  J7=9  G1=9S2But also:J3=2  E3=4, E2=3  F2=4c  B1=9S6Which is impossible. Hence:J3=6

11. Solving…With the naked triple in J468 (yellow) we can remove 47 from J1.This gives us anX-wing on 4 at EF12, which removes 4 from F4.

12. Final test: J7=9Keeping in mind the links we already discovered, we find that J7 cannot be 9:J7=9  G2=9, B1=6  F2=6 and F4=7But also:J7=9  H7=8  H6=7, J6=8, J8=4 and J4=7Thus: J7=2The rest is easy.

13. SolutionThere are of course other (maybe easier) ways to solve this puzzle. This solution emphasized links between cells and different areas of the board to test and eliminate candidates.

14. 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

15. Diabolic Str8ts Puzzle #1Solution by SlowThinkerNote: there are other (maybe easier) ways to solve this puzzle.View & download my strategy slides from:http://slideshare.net/SlowThinker/str8ts-basic-and-advanced-strategiesor from Google Docs:http://is.gd/slowthinker_str8ts_strategy