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h3lix
 Post subject: Vanilla Anti Knight
PostPosted: Wed May 26, 2010 10:10 pm 
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Here's what may be the first sudoku puzzle I've ever designed that did not in some way involve sum cages.

It's a basic Anti-Knight

MEDIUM version:
Image
000060000000040000000203000001000400420000018008000500000706000000030000000050000


INSANE version:
Image
000060000000040000000203000001000400020000010008000500000706000000030000000050000


A few notes:

1. The MEDIUM version can be solved rather straightforwardly using a few hidden singles and pointing techniques. I'm still going fishing on the INSANE version on paper...quite a challenge. JSudoku verifies that it has only one solution, but for some reason SudokuSolver always goes down an incorrect solve path and can't find the solution.

2. The puzzle still has a unique solution without any givens on R19 or C19, but JSudoku solvers can't crack it.

Edit: here's the scan of the paper on which I was working the INSANE version.

How the magic happens:
Image

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Ed
 Post subject: Re: Vanilla Anti Knight
PostPosted: Sun May 30, 2010 10:55 am 
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h3lix wrote:
Here's what may be the first sudoku puzzle I've ever designed that did not in some way involve sum cages.
And this is the first non-cage/non-tail sudoku I've tried in a long time. I started with the Insane version, got stuck so added the extra clues from the Medium, got stuck....and stucker..until finally noticing that I'd missed some of the AN eliminations from the initial clues! That helped. :D

h3lix wrote:
It's a basic Anti-Knight
What does "Anti" mean? Perhaps it will help with the Insane... ;)

h3lix wrote:
but for some reason SudokuSolver always goes down an incorrect solve path and can't find the solution.
It gets the Medium OK but you have to untick all the routines that have the word "Chain" in them to get it to solve/score the Insane. Must be a bug.

h3lix wrote:
I'm still going fishing on the INSANE version on paper...quite a challenge....Edit: here's the scan of the paper on which I was working the INSANE version.
Why don't we compare notes. Here's where I'm at.
Code:
.-------------------------------.-------------------------------.-------------------------------.
| 4589      4789      3         | 18        6         1789      | 1279      24578     145789    |
| 2689      678       279       | 5         4         19        | 3         678       178       |
| 45689     1         569       | 2         78        3         | 69        4567      79        |
:-------------------------------+-------------------------------+-------------------------------:
| 35        35        1         | 6         78        78        | 4         9         2         |
| 467       2         46        | 3         9         5         | 78        1         678       |
| 679       69        8         | 4         1         2         | 5         37        367       |
:-------------------------------+-------------------------------+-------------------------------:
| 1         358       459       | 7         2         6         | 89        345       3489      |
| 24568     456       67        | 9         3         48        | 1678      278       14578     |
| 234689    34678     2469      | 18        5         148       | 2789      23467     34789     |
'-------------------------------.-------------------------------.-------------------------------'
I've really enjoyed trying this one. So many interesting moves.

Cheers
Ed
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HATMAN
 Post subject: Re: Vanilla Anti Knight
PostPosted: Sun May 30, 2010 6:27 pm 
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I got stuck on paper on the medium - probably something obvious, so I'll try again from scratch.

By the way I prefer to spell it Anti-kNight to distinguish from Anti-King.
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h3lix
 Post subject: Re: Vanilla Anti Knight
PostPosted: Sun May 30, 2010 10:17 pm 
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Quote:
What does "Anti" mean? Perhaps it will help with the Insane... ;)

I don't particularly like that chess piece because it often takes so many turns to put it in an advantageous position. ;)


I started SudokuSolver on scoring this puzzle after turning off all the chains this morning and it's still solving...


At the time of that scan, I was at the same point you were, except I had not solved as much of R4 yet (btw R4C12 = [35] because of AN on R5C4)

The next step for me involved a lot of 7's

images showing strong links for 1, 2, and 7:
ImageImageImage


7 in R2C3 forces 2 in R9C4 and R1C7, which forces 1 in R8C7, then 7 in R9C7, which removes all 7's from N7.
=> R2C3 != 7

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HATMAN
 Post subject: Re: Vanilla Anti Knight
PostPosted: Wed Jun 02, 2010 8:56 am 
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I managed the medium on at last - I kept missing linkages.
It was just about as hard as I can do on paper - thanks Dan.
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Ed
 Post subject: Re: Vanilla Anti Knight
PostPosted: Thu Jun 03, 2010 6:51 am 
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Worked out how to finish off the Insane version.


I'm not exactly sure how you did your move h3lix but this is a way I can see that very helpful elimination.

From my marks pic above with r4c12 = [35] ( :oops: )

1. No 7 in r2c3. Like this. r47c6 = (478) -> must have at least one of 4/7.
1a. If r8c6 = 4 -> r8c23 = [67] -> no 7 in r2c3
1b. if r4c6 = 7 -> r4c5 = 8 -> r3c5 = 7 -> no 7 in r2c3 from AN

But that move still didn't crack it for me.

Here's another step which works from my marks spot above (with r4c12 = [35]) which combined with step 1 does crack it.
2. no 9 in r3c7 because of r5c7. Like this. r5c7 = (78)
2a. if 7 -> r4c5 = 8 (from AN) -> r3c5 = 7 -> r3c9 = 9 -> no 9 in r3c7
2b. If r5c7 = 8 -> r7c7 = 9 -> no 9 in r3c7

Solution: 
+-------+-------+-------+
| 9 4 3 | 8 6 1 | 2 7 5 |
| 6 7 2 | 5 4 9 | 3 8 1 |
| 8 1 5 | 2 7 3 | 6 4 9 |
+-------+-------+-------+
| 3 5 1 | 6 8 7 | 4 9 2 |
| 4 2 6 | 3 9 5 | 7 1 8 |
| 7 9 8 | 4 1 2 | 5 3 6 |
+-------+-------+-------+
| 1 8 4 | 7 2 6 | 9 5 3 |
| 5 6 7 | 9 3 8 | 1 2 4 |
| 2 3 9 | 1 5 4 | 8 6 7 |
+-------+-------+-------+

We got there!

h3lix wrote:
I started SudokuSolver on scoring this puzzle after turning off all the chains this morning and it's still solving...
SS is usually pretty quick so it must have found another problem. It needs the Bingo Lite routine/ ALS Complex ticked to get it to solve without the chains. I'm guessing it is still on the "default" routines settings which has these unticked. I always have the "scoring" routines as my "default" list (use solver-options-scoring radio button-save radio button). The scoring routine which will then be the one that opens whenever SS opens - which includes Bingo (the Lite Bingo can often be much more human-like, though not in this puzzle, than the ALS Complex).

Cheers
Ed
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