Assassin 5

[Caida]

I've been doing an inventory of the walkthroughs available and noticed that Assassin 5 didn't have a walkthrough.

I learned to do killers by going step by step through the walkthroughs I found on this forum and I always figured that no walkthrough meant that the assassin was impossible to do (or at least well out of my range of skills). Looking at this one I think perhaps I could have tried it earlier

I'd rate it a 0.75 at the most - the whole thing can be solved with cage combinations and some easy 45 rules.

Cheers

Caida


Here's the walkthrough - I'll not bother with tiny text as it is super old.


Assassin 5 walkthrough

Preliminaries:

a. 7(2)n1 = {16/25/34} (no 7..9)
b. 21(3)n23 = {xx} (no 1..3)
c. 3(2)n3 and n7 = {12} (no 3..9) -> 1, 2 locked for n3 and n7 and r1 and r8
d. 14(2)n3 and n45 = {59/68} (no 1..4, 7)
e. 9(2)n3 and n47 and n7 = {18/27/36/45} (no 9)
f. 10(2)n36 and n9 = {19/28/37/46} (no 5)
g. 9(3)n56 = {xxx} (no 7..9)
h. 17(2)n56 and n7 = {89} (no 1..7) -> 8, 9 locked for r6 and n7 and r9
i. 11(3)n69 = {xx} (no 9)

cleanup:
j. r2c1 no 5,6
k. r3c78 no 7,8
l. r4c9 no 8,9
m. r6c1 no 1, 7
n. r7c23 no 7
o. 3 locked in n3 in r3 -> no 3 elsewhere in r3


1. Outies n3: r1c6+r4c9 = 12(2) = [93/84/66/57]
1a. -> r1c6 no 4,7
1b. -> r4c9 no 1,2
1c. cleanup: r3c9 no 8,9

2. Outies n7: r6c1+r9c4 = 5(2) = [23/32/41]
2a. -> r6c1 no 5,6
2b. -> r9c4 no 4,5,6,7
2c. cleanup: r7c1 no 3,4

3. Innies n8: r7c6+r9c4 = 7(2) = [61/52/43]
3a. -> r7c6 no 1,2,3,7,8,9

4. Innies n789: r7c19 = 9(2) = [54/63/72]
4a. -> r7c9 no 1,5,6,7,8

5. Innie and Outie n1: r3c4-r3c1 = 3
5a. -> r3c4 no 1,2,6
5b. -> r3c1 no 7,8,9

6. Innies n2: r1c6+r3c4 = 14(2) = [59/68/95]
6a. -> r1c6 no 8
6b. -> r3c4 no 4,7
6c. cleanup: r3c1 no 1,4 (step 5)
6d. r4c9 no 4 (step 1)
6e. r3c9 no 6

7. Innies r12: r2c56 = 10(2) = {19/28/37/46} (no 5)
7a. -> split 19(4)n2: r3c56 = 9(2) = {18/27/45} (no 6,9)

8. Innies r89: r8c34 = 12(2) = {39/48/57} (no 6)
8a. -> split 22(4)n8: r7c34 = 10(2) = {19/28/37/46} (no 5)

9. Innie r1234: r4c5 = 4
9a. Innie r6789: r6c5 = 3
9b. cleanup: r2c6 no 6,7
9c. r3c6 no 5
9d. r7c4 no 6,7
9e. r8c4 no 8,9
9f. r7c1 no 6
9g. r9c4 no 2
9h. r7c6 no 5
9i. r7c9 no 3

10. 12(3)n78 = {47}[1]/{45}[3]
Note: combo {56}[1] blocked by 9(2)n7
10a. -> r89c3 no 3,6
10b. -> 4 locked in r89c3 for n8 and c3
10c. -> 9(2)n8 = {36} -> locked for n8 and r7
10d. single: r7c6 = 4
10e. -> r7c9 = 2
10f. r67c1 = [27]
10g. r8c12 = [12]
10h. r1c89 = [21]
10i. 12(3)n78 = {45}[3] -> 5 locked for c3

11. 22(4)n8 = {19}{57} -> locked for n8
11a. -> {19} locked for r7
11b. -> {57} locked for r8
11c. -> r89c3 = [45]
11d. single; r8c6 = 8


cage sums and singles to the end

Solution:
398465721
451273968
672981453
839542617
546817239
217639845
763194582
124758396
985326174

[Andrew]

I've been doing an inventory of the walkthroughs available and noticed that Assassin 5 didn't have a walkthrough.

There were 3 early Assassins that never got posted walkthroughs. They are all easy Assassins. I think there must still be at least one that doesn't have a walkthrough.

I didn't start writing walkthroughs until Assassin 13 although I did go through posted walkthroughs for earlier ones and provide feedback where appropriate.

I learned to do killers by going step by step through the walkthroughs I found on this forum and I always figured that no walkthrough meant that the assassin was impossible to do (or at least well out of my range of skills). Looking at this one I think perhaps I could have tried it earlier

I'd rate it a 0.75 at the most - the whole thing can be solved with cage combinations and some easy 45 rules.

On Mike's definition of the ratings, you can't rate this puzzle any lower than 0.75! The definition of 0.75 was for very early Assassins with A1 being specifically mentioned. Unless there are any Assassins significantly easier than A1, which I doubt, then all Assassins must be rated at least 0.75.

You probably found Assassin 5 slightly easier than I did because you were using elimination solving. I solved as least the first 18 Assassins by insertion solving before I started using elimination solving.

When I first started solving Assassins I found them significantly harder than the daily Diabolicals on www.sudoku.org.uk which I think are about the same level as The Times Deadly that Mike defined as being 0.5.

[Caida]

There were 3 early Assassins that never got posted walkthroughs. ... I think there must still be at least one that doesn't have a walkthrough.

From what I can find # 10 is the only one (apart from the "unsolveables") that doesn't have a walkthrough.
It is on my list of "to try"

On Mike's definition of the ratings, you can't rate this puzzle any lower than 0.75!

Then I guess I'll go with 0.75

You probably found Assassin 5 slightly easier than I did because you were using elimination solving. I solved as least the first 18 Assassins by insertion solving before I started using elimination solving.

I'm not sure what insertion solving entails- I'll take a look at your earlier walkthroughs to see.

When I first started solving Assassins I found them significantly harder than the daily Diabolicals on www.sudoku.org.uk which I think are about the same level as The Times Deadly that Mike defined as being 0.5.

I do the daily puzzles on sudoku.org.uk and (since I learned how to do them) I have yet to find a killer puzzle there (including the "extremes") that is as hard as any I find here.

Does anyone else have an opinion on the rating for Assassin 5?

Cheers,

Caida

[mhparker]

From what I can find # 10 is the only one (apart from the "unsolveables") that doesn't have a walkthrough.

Maybe A1 as well. Don't remember finding a WT for that. There's a V2 (released about a year later), but that's a different story.

I'm not sure what insertion solving entails- I'll take a look at your earlier walkthroughs to see.

I suspect Andrew just means starting with an empty grid and inserting pencilmarks, rather than starting with a grid of 9x9x9 candidates and successively eliminating those that are no longer possible.

When I first started solving Assassins I found them significantly harder than the daily Diabolicals on www.sudoku.org.uk which I think are about the same level as The Times Deadly that Mike defined as being 0.5.

The Times Deadlies do vary. But AFAIK, none of them require triple or quadruple innies and outies, I/O difference, conflicting combinations, and killer subsets, for example. Of course, people like us may still be able to find a use for such techniques on some of these puzzles, but they are not essential. Also, there are usually several single innies or outies available, and permuatations are normally only used in trivial cases on 2 or (at most) 3-cell original cages.

[Andrew]

I do the daily puzzles on sudoku.org.uk and (since I learned how to do them) I have yet to find a killer puzzle there (including the "extremes") that is as hard as any I find here.

This week's extreme killer #64 on that website is a bit more of a challenge but I think it's probably still easier than any of the early Assassins.

I'm not sure what insertion solving entails- I'll take a look at your earlier walkthroughs to see.

I suspect Andrew just means starting with an empty grid and inserting pencilmarks, rather than starting with a grid of 9x9x9 candidates and successively eliminating those that are no longer possible.

Spot on Mike. After inserting any values that can be fixed immediately I then put in pairs, etc that only have one combination, followed by those with two combinations. I actually insert 59/68 in each of the 2 cells of a 14(2) cage rather than 5689. I still solve all killers on sudoku.org.uk that way.

I was intending to comment somewhere on the phrase "pencilmarks" which is used in the definition of the 0.5 rating. It is clearly widely used to mean marks inserted in cells, hence the use of the term "marks pic". However I've tended to think of pencilmarks in a different way; I use them to add notes outside the grid indicating numbers which must be in a group of 3 cells in a row/column. When I first saw the term pencilmarks I thought that's what it meant. I find them very useful for insertion solving and still occasionally use them as a reminder for elimination solving.