Mike wrote:An attractive but deadly cage pattern that should require a tad more brain power than last week's puzzle, although nothing an experienced Assassin forum member shouldn't be able to handle...
Wow, this was a tough one! It stretched my brain power to the limit.
The start was easy, then I ground to a halt and went off to solve YAK94 and then uA95 before I came back and found the key contradiction move. Afmob presents it (steps 5a and 5b) as a clash/block but I felt it is really a short contradiction move (my step 25a). Maybe be source of my difficulty is that the killer pair (my step 23e) mask the fact that they are also used as part of a contradiction move. Very clever Mike!
Between solving YAK94 and uA95 I had another look at this from the start and found a couple of interesting combined cages, particularly the one in step 14; the other one in step 16 didn't really lead anywhere but I've kept it in for completeness.
There are so many possible sets of 4 outies but I only found a couple of them were useful; the one on N3 was the better of the two while the one on R123 gave me a hidden single later.
If I had to rate this puzzle, then it's a 1.25 just on the moves but if difficuly in finding the key breakthrough is taken into account then IMHO it's a 1.5. Clearly Caida, Afmob and Ed (off-forum) thought otherwise since they found breakthrough combination moves much more easily.
Here is my walkthrough
Prelims
a) R1C34 = {29/38/47/56}, no 1
b) R12C5 = {16/25/34}, no 7,8,9
c) R1C67 = {17/26/35}, no 4,8,9
d) R89C5 = {{69/78}
e) R9C34 = {16/25/34}, no 7,8,9
f) R9C67 = {59/68}
g) R3C456 = {389/479/569/578}, no1,2
h) R234C9 = {489/579/678}, no 1,2,3
i) R456C5 = {126/135/234}
j) R5C123 = {289/379/469/478/568}, no 1
k) R5C789 = {123}, locked for R5 and N6
l) R678C9 = {127/136/145/235}, no 8,9
m) 11(3) cage in N7 = {128/137/146/236/245}, no 9
n) 33(5) cage at R4C6 = {36789/45789}, no 1,2
1. R456C5 = {126/135/234}
1a. R5C5 = {456} -> no 4,5,6 in R46C5
2. R678C9 = {127/136/145/235}
2a. 6,7 of {127/136} must be in R6C9 -> no 6,7 in R78C9
3. 45 rule on R1 3 outies R2C258 = 8 = 1{25/34}, 1 locked for R2, clean-up: no 1 in R1C5
4. 45 rule on R9 3 outies R8C258 = 20 = {389/479/569/578}, no 1,2
5. 45 rule on C1234 2 innies R37C4 = 8 = {35}/[62/71]
6. 45 rule on C6789 2 innies R37C6 = 13 = {49/58/67}, no 1,2,3
7. 45 rule on C5 2 innies R37C5 = 14 = {59} (cannot be {68} which clashes with R89C5), locked for C5, clean-up : no 2 in R12C5, no 6 in R89C5
8. Naked pair {78} in R89C5, locked for N8, clean-up: no 5,6 in R3C6 (step 6), no 6 in R9C7
8a. 2 in C5 locked in R46C5, locked for N5
9. R8C258 (step 4) = {389/479/578} (cannot be {569} because R8C5 only contains 7,8), no 6
9a. 9 of {389/479} must be in R8C8 -> no 3,4 in R8C8
10. R3C456 = {389/479/569/578}
10a. 4,8 of {479/578} must be in R3C6 -> no 7 in R3C6, clean-up: no 6 in R7C6 (step 6)
10b. 6 of {569} must be in R3C4, 5 of {578} must be in R3C5 -> no 5 in R3C4, clean-up: no 3 in R7C4 (step 5)
11. R7C456 = {159/249}, 9 locked for R7 and N8, clean-up: no 5 in R9C7
11a. 1,2 only in R7C4 -> R7C4 = {12}, clean-up: no 3 in R3C4 (step 5)
12. 9 in R9 locked in R9C789, locked for N9
12a. R8C258 (step 9) = {578} (only remaining combination), locked for R8
13. 11(3) cage in N7 = {128/137/245} (cannot be {146/236} because R8C2 only contains 5,7,8), no 6
13a. R8C2 = {578} -> no 5,7,8 in R9C12
14. Combined cage 11(3) in N7 + R9C34 = 18(1+4) = 5{1246}/7{1235}/8{1234} (cannot be 5{1346} which isn’t consistent with 11(3) cage), 1,2 locked for R9
15. 18(3) cage in N9 = {378/459/468/567} (cannot be {369} because R8C8 only contains 5,7,8)
15a. 5 of {459} must be in R8C8, 5 of {567} must be in R8C8 (cannot be 7{56} which clashes with R9C6) -> no 5 in R9C89
16. Combined cage 18(3) in N9 + R9C67 = 32(1+4) and must contain 9 (step 12) = 5{4689/5679}/7{3589}/8{3579/3678} (cannot be 8{4569} which clashes with 5{1246} in combined cage 11(3) in N7 + R9C34, other combinations for R9C6789 aren’t consistent with 18(3) cage)
16a. -> 18(3) cage in N9 = {378/459/567} (cannot be {468} which doesn’t fit in combined cage)
17. 45 rule on R5 3 innies R5C456 = 20 = {479/569} (cannot be {578} because R5C5 only contains 4,6), no 8, 9 locked for R5 and N5
17a. R5C5 = {46} -> no 4,6 in R5C46
17b. 8 in R5 locked in R5C123, locked for N4
18. 45 rule on C1 3 innies R159C1 = 12 = {138/147/156/237/246/345} (cannot be {129} because no 1,2,9 in R5C1), no 9
18a. 8 of {138} must be in R5C1 -> no 8 in R1C1
19. 45 rule in C9 3 innies R159C9 = 14 = {149/167/239/248/257/356} (cannot be {158/347} which clash with R234C9)
19a. 1 of {149/167} must be in R5C9 -> no 1 in R1C9
20. 45 rule on R123 4 outies R4C1289 = 17, min R4C89 = 9 -> max R4C12 = 8, no 9
21. 45 rule on N3 4 outies R12C6 + R4C89 = 16, min R4C89 = 9 -> max R12C6 = 7, no 7,8,9, no 6 in R1C6, clean-up: no 1,2 in R1C7
22. 7 in C6 locked in R456C6, locked for N5 and 33(5) cage -> no 7 in R46C7
23. R3C456 (step 10) = {479/569/578}
23a. Hidden killer pair 8,9 in R12C4 and R3C456 for N2 -> R12C4 must contain one of 8,9
23b. Hidden killer pair 8,9 in R12C4 and R456C4 for C4 -> R456C4 must contain one of 8,9
23c. Hidden killer pair 8,9 in R456C4 and R456C6 for N5 -> R456C6 must contain one of 8,9
23d. Hidden killer pair 8,9 in R456C6 and R46C7 for 33(5) cage -> R46C7 must contain one of 8,9
23e. Killer pair 8,9 in R46C7 and R9C7, locked for C7
[A slightly shorter version starts with hidden killer pair 8,9 in R37C6 and R456C6.]
24. 33(5) cage at R4C6 = {36789/45789}
24a. 7 in C6 locked in R456C6 (step 22)
24b. R456C6 must contain one of 8,9 (step 23c) -> only one of 3,4,5,6 is in R456C6
24c. 3 of {36789} must be in R46C6 -> no 6 in R46C6
25. R456C6 and R46C7 must each contain one of 8,9 (steps 23c and 23d)
25a. If R46C7 contains 8 => R9C67 = [59], R5C6 = 9, R37C6 = [85] clashes with R9C6
25b. -> no 8 in R46C7, 9 locked in R46C7, locked for C7, N6 and 33(5) cage -> R9C7 = 8, R9C6 = 6, R89C5 = [87], clean-up: no 1 in R9C34
26. 9 in C6 locked in R37C6 (step 6) = {49}, locked for C6
26a. 8 in C6 locked in R46C6, locked for N5
26b. R5C4 = 9 (hidden single in N5), clean-up: no 2 in R1C3
26c. R4C7 = 9 (hidden single in R4)
26d. 9 in N2 locked in R3C56, locked for R3
27. R234C9 = {489/579/678}
27a. 9 of {489/579} must be in R2C9 -> no 4,5 in R2C9
28. 1 in R9 locked in R9C12, locked for N7
28a. 11(3) cage in N7 (step 13) = {137} (only remaining combination) -> R8C2 = 7, R9C12 = {13}, locked for R9 and N7, R8C8 = 5, clean-up: no 4 in R9C34
28b. Naked pair {49} in R9C89, locked for N9
29. Naked triple {123} in R578C9, locked for C9
29a. R678C9 = {127/136/235} (cannot be {145} because 4,5 only in R6C9), no 4
30. Killer pair 2,5 in R7C456 and R9C4, locked for N8
30a. 2 in N8 locked in R79C4, locked for C4, clean-up: no 9 in R1C3
31. 6,7 in N9 locked in R7C78 + R8C7, locked for 25(5) cage -> no 6,7 in R6C8
31a. 25(5) cage at R6C8 = {13678} (only remaining combination), no 2,4 -> R6C8 = 8
31b. R4C6 = 8 (hidden single in R4)
32. 2 in N9 locked in R78C9, locked for C9
32a. R678C9 (step 29a) = {127/235}, no 6
33. 12(3) cage in N3 = {129/138/147/237/246}
33a. 9 of {129} must be in R1C9 -> no 9 in R1C8
34. R9C8 = 9 (hidden single in C8), R9C9 = 4
35. R234C9 = {579/678}, 7 locked for C9 -> R6C9 = 5
35a. R234C9 = {678}, locked for C9 -> R1C9 = 9, R12C8 (step 33) = {12}, locked for C8 and N3 -> R5C8 = 3, R5C79 = [21]
36. Naked pair {23} in R78C9, locked for N9 -> R8C6 = 3 (step 31a), R56C6 = [57], R12C6 = [12], R1C7 = 7, R12C8 = [21], R6C7 = 4 (step 24), R78C9 = [32], clean-up: no 4 in R1C34, no 6 in R1C5
37. Naked pair {16} in R78C7, locked for C7 and N9 -> R7C8 = 7, R4C89 = [67], R3C8 = 4, R3C6 = 9, R3C5 = 5, R3C4 = 6 (step 23), R23C7 = [53], R23C9 = [68], R7C56 = [94], R78C4 = [21], R46C4 = [43], R12C4 = [87], R1C3 = 3, R12C5 = [43], R2C2 = 4, R5C5 = 6, R78C7 = [16], R9C34 = [25], R3C23 = [21], R3C1 = 7, R46C3 [56], R7C3 = 8, R2C13 = [89], R8C13 = [94], R5C123 = [487], R4C2 = 3, R9C12 = [31], R6C2 = 9
38. R8C1 = 9 -> R67C1 = 8 = [26]
and the rest is naked singles
5 6 3 8 4 1 7 2 9
8 4 9 7 3 2 5 1 6
7 2 1 6 5 9 3 4 8
1 3 5 4 2 8 9 6 7
4 8 7 9 6 5 2 3 1
2 9 6 3 1 7 4 8 5
6 5 8 2 9 4 1 7 3
9 7 4 1 8 3 6 5 2
3 1 2 5 7 6 8 9 4