Prelims
a) R1C56 = {18/27/36/45}, no 9
b) R45C9 = {12}
c) R5C56 = {19/28/37/46}, no 5
d) R67C8 = {14/23}
e) R8C78 = {14/23}
f) R9C12 = {14/23}
g) R9C89 = {79}
h) 6(3) cage at R2C3 = {123}
i) 21(3) cage at R2C5 = {489/579/678}, no 1,2,3
j) 11(3) cage at R6C1 = {128/137/146/236/245}, no 9
k) 26(4) cage at R1C9 = {2789/3689/4589/4679/5678}, no 1
l) 36(8) cage at R1C7 = {12345678}, no 9
m) 43(8) cage at R6C3 = {13456789}, no 2
Steps resulting from Prelims
1a. Naked pair {12} in R45C9, locked for C9 and N6, clean-up: no 3,4 in R7C8
1b. Naked pair {79} in R9C89, locked for R9 and N9
1c. Naked triple {123} in 6(3) cage at R2C3, CPE no 1,2,3 in R2C12
1d. Killer pair 1,2 in R7C8 and R8C78, locked for N9
1e. 9 in C7 only in R46C7, locked for N6
2. 45 rule on N1 2 outies R12C4 = 6 = [42/51]
2a. 6(3) cage at R2C3 = {123}, 3 locked for C3 and N1
2b. R1C56 = {18/27/36} (cannot be {45} which clashes with R1C4), no 4,5 in R1C56
3. 21(3) cage at R2C5 = {489/579} (cannot be {678} which clashes with R1C56), no 6, 9 locked for N2
3a. Killer pair 4,5 in R1C4 and 21(3) cage, locked for N2
4. 45 rule on C9 2 outies R29C8 = 16 = {79}, locked for C8
4a. 36(8) cage at R1C7 = {12345678}, 7 locked for C7
5. 45 rule on C789 4 innies R4679C7 = 28 = {5689} (only possible combination), locked for C7
6. 45 rule on N3 3 outies R4C8 + R5C78 = 17 = {368/458/467}
6a. 3 of {368} must be in R5C7 -> no 3 in R45C8
6b. Killer pair 3,4 in R4C8 + R5C78 and R6C8, locked for N6
[Afmob pointed out that the killer pair also eliminates 3,4 from R13C8]
7. 21(4) cage at R1C1 must contain one of 1,2 (because {4567}=22)
7a. Killer pair 1,2 in 21(4) cage and 6(3) cage at R2C3, locked for N1
8. 45 rule on C12 3(2+1) outies R1C34 + R8C3 = 11
8a. Min R1C4 = 4 -> max R18C3 = 7, no 7,8,9 in R18C3
8b. R18C3 must contain one of 1,2 (because no 3 in R18C3) -> killer pair 1,2 in R18C3 and 6(3) cage at R2C3, locked for C3
9. 45 rule on N47 5 innies R45679C3 = 34 = {46789}, locked for C3
10. R1C34 + R8C3 = 11 (step 8)
10a. R1C4 = {45} -> R18C3 = [15]/{25}, no 1 in R8C3
10b. 1 in C3 only in R123C3, locked for N1
11. 35(6) cage at R3C4 = {146789/236789/345689} (cannot be {245789} which clashes with R12C4)
11a. 4 of {146789/345689} must be in R45C3 (R3456C4 cannot contain both of 1,4 which would clash with R12C4, cannot contain both of 4,5 which would clash with R1C4), no 4 in R456C4
12. 45 rule on C1234 3 innies R6C3 + R7C34 = 1 outie R9C5 + 20
12a. Max R6C3 + R7C34 = 24 -> max R9C5 = 4
12b. Min R6C3 + R7C34 = 21, no 1,3 in R7C4
13. 43(8) cage at R6C3 = {13456789}, CPE no 1,3 in R45C5, clean-up: no 7,9 in R5C6
14. 45 rule on N8 2 outies R9C37 = 2 innies R7C45 + 3
14a. Max R9C37 = 14 -> max R7C45 = 11, min R7C4 = 4 -> max R7C5 = 7
15. 18(4) cage at R8C4 = {1368/1458/1467/2358/2367/3456} (cannot be {1269/1278/2349/2457} which clash with R9C12, cannot be {1359} because R9C3 only contains 4,6,8), no 9
15a. 7 of {1467/2367} must be in R8C4, 6 of {1368/3456} must be in R9C34 (R9C345 cannot be {138/345} which clash with R9C12), no 6 in R8C4
16. 45 rule on R6789 1 innie R6C4 = 1 outie R5C2 + 3, no 1,7,8,9 in R5C2, no 1,2,3 in R6C4
[I ought to have spotted this a lot sooner …]
17. Max R1C34 = 9 -> min R1C12 = 12, no 2 in R1C12
17a. 2 in N1 only in R123C3, locked for C3 -> R8C3 = 5, clean-up: no 8 in R6C4 (step 16)
18. 11(3) cage at R6C1 = {128/137/146/236} (cannot be {245} = 5{24} which clashes with R9C12), no 5 in R6C1
18a. 7,8 of {128/137} must be in R78C1 (R78C1 cannot be {12/13} which clash with R9C12), no 7,8 in R6C1
19. 5 in R9 only in R9C467, CPE no 5 in R7C6
[Note that when R9C7 contains 5 then R7C45 must contain 5, when R9C7 doesn’t contain 5 then R7C45 doesn’t contain 5.]
19a. R9C37 = R7C45 + 3 (step 14)
19b. R9C37 = [45/46/48/65/68/86] (cannot be [85] = 13 because R7C45 cannot total 10 containing 5) = 9,10,11,12,14 -> R7C45 = 6,7,8,9,11 = [51/43/61/53/47/63/81/74/83] -> R7C4 = {45678}, R7C5 = {1347}
[Thanks Afmob for pointing out that I’d accidentally omitted R9C37 = [48]. Fortunately it doesn’t affect the result of this step, although it did make changes to steps 20 and 21 and made step 25a more complicated.]
20. 18(4) cage at R8C4 (step 15) = {1368/1458/1467/2358/2367/3456}, R7C45 (step 19b) = [51/43/61/53/63/81/47/74/83]
20a. 9 in N8 only in 30(5) cage at R7C6 = {15789/24789/25689/34689/35679}
20b. Consider combinations for 30(5) cage
30(5) cage = {15789/24789/34689/35679} => R7C45 = [51/43/61/53/63/81/83] (cannot be {47})
or 30(5) cage = {25689}, 2 locked for N8 => 18(4) cage = {1458/1467/3456} (cannot be {1368} with 6,8 in R9C34, to avoid clash with R9C12, which clashes with 30(5) cage = {2689}5) => R7C45 = [51/43/61/53/63/81/83] (cannot be {47})
-> R7C45 = [51/43/61/53/63/81/83], no 7 in R7C4, no 4,7 in R7C5
21. 1 of 43(8) cage at R6C3 must be in R6C56 (R6C56 + R7C5 cannot be [3x]1 which clashes with R67C8) -> R7C5 = 3, 1 in R6C45, locked for R6 and N5, clean-up: no 6 in R1C6, no 9 in R5C5
22. 3 in R9 only in R9C12 = {23}, locked for R9 and N7
23. 11(3) cage at R6C1 (step 18) = {128/137/146} (cannot be {236} because 2,3 only in R6C1), 1 locked for C1 and N7
23a. R4C2 = 1 (hidden single in N4), R45C9 = [21]
23b. R4C2 = 1 -> R45C1 = 11 = {38/47/56/[92], no 9 in R5C1
24. 18(4) cage at R8C4 (step 15) = {1458/1467}, no 2, 1 locked for N8
24a. 5 of {1458} must be in R9C4 -> no 8 in R9C4
24b. 1 in R9 only in R9C45, locked for N8
24c. 4 in R9 only in R9C3456, CPE no 4 in R8C4
24d. R8C4 = {78} -> no 8 in R9C3
25. 18(4) cage at R8C4 (step 24) = {1458/1467}
25a. 2 in N8 only in 30(5) cage at R7C6 (step 20a) = {25689} (only remaining combination, cannot be {24789} = {279}48 which clashes with R78C4 because R9C67 = [48] would require R9C3 = 6, R9C37 = [68] -> R7C45 = [83], step 19b)
26. R8C4 = 7 (hidden single in N8) -> 18(4) cage at R8C4 (step 24) = {1467}, 6 locked for R9, clean-up: no 4 in R5C2 (step 16)
26a. Naked pair {58} in R9C67 -> R7C6 + R8C56 = {269}, locked for N8
26b. R9C3 = 6 (hidden single in R9)
26c. Killer pair 1,4 in R12C4 and R9C4, locked for C4
27. 9 in C4 only in R456C4, locked for N5 and 35(6) cage at R3C4, no 9 in R45C3
28. 9 in C3 only in R67C3, locked for 43(8) cage at R6C2, no 9 in R6C7
28a. R4C7 = 9 (hidden single in C7), clean-up: no 2 in R5C1 (step 23b)
28b. R5C4 = 9 (hidden single in R5), clean-up: no 6 in R5C2 (step 16)
29. 35(6) cage at R3C4 (step 11) = {236789/345689}
29a. R45C3 = {478} -> no 8 in R34C4
30. R7C4 = 8 (hidden single in C4)
30a. R67C7 = {56}, locked for C7 and 43(8) cage at R6C3 -> R9C67 = [58]
31. 2 in R6 only in R6C12, locked for N4 -> R5C2 = 3, R6C4 = 6 (step 16), R67C7 = [56], R9C12 = [32], clean-up: no 4,7 in R5C5, no 4 in R5C6
31a. Naked pair {28} in R5C56, locked for R5 and N5
32. R6C8 = 3 (hidden single in R6), R7C8 = 2, R7C6 = 9, clean-up: no 3 in R8C7
32a. R8C78 = {14}, locked for R8 and N9 -> R8C1 = 8, R8C2 = 9, R78C9 = [53], R6C9 = 8 (cage sum)
32b. R67C1 = [21] (hidden pair in C1)
32c. R45C1 = {56} (hidden pair in N4), locked for C1
32d. Naked triple {479} in R123C1, locked for N1
33. R5C1 = 5 (hidden single in R5), R4C1 = 6, R45C8 = [46], R5C7 = 7, R5C3 = 4, R6C2 = 7, R8C78 = [41]
34. R45C3 + R56C4 = [8496] = 27 -> R34C4 = 8 = [35]
34a. R4C56 = [73], R4C7 = 9, R3C6 = 6 (cage sum)
35. Deleted, unnecessary
and the rest is naked singles.