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 Post subject: Ordered NC 1
PostPosted: Sat Dec 28, 2019 5:33 pm 
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Grand Master
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Joined: Wed Apr 30, 2008 9:45 pm
Posts: 693
Location: Saudi Arabia
Ordered NC Vanilla 1

I always find that NC is too restrained and CNC even more so, hence when trying to make a killer the cages end up too large. They also cause what I call the cliff-edge problem: add a clue to make the puzzle solvable and then it is too easy. This is particularly the case with MeanDoku.

I therefore thought to reduce the restraint by requiring NC in one direction only. I have gone for rejecting increasing as they are slightly more obvious visually. Due to reduced interactions the restraint level is reduced by more than 50%, I would guess to about one third.

Ordered (orthogonal) NC: horizontally and vertical increasing consecutive numbers are not allowed so 9-8 is OK but 8-9 is not.

tarek has kindly provided me with a set of solutions so here is the first one.

Probably medium difficulty once you are used to it, as it took me a few tries to do it without fishes.


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 Post subject: Re: Ordered NC 1
PostPosted: Sun Dec 29, 2019 10:26 pm 
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Grand Master
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Joined: Wed Apr 23, 2008 6:04 pm
Posts: 1893
Location: Lethbridge, Alberta, Canada
I'm not really into vanilla sudokus but I tried this one in case it might lead to killers with the same condition.

Here's how I solved it:
For the final stages, after earlier looking at interactions within nonets, I used some slightly larger interactions, first R5 with N6, then C4 with C5; not sure whether they'd count as fishes.

Solution:
3 1 4 6 9 8 7 2 5
2 7 6 3 1 5 9 4 8
8 5 9 2 4 7 3 6 1
4 3 8 1 7 2 5 9 6
7 6 2 9 5 4 1 8 3
1 9 5 8 3 6 4 7 2
6 4 7 5 8 3 2 1 9
5 2 1 4 6 9 8 3 7
9 8 3 7 2 1 6 5 4


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