## Stuck - Lovatt's Issue 1 #96 (Genius)

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### Stuck - Lovatt's Issue 1 #96 (Genius)

Dubbed into Sud.exe from this site, rated as HARD.

Can you please tell me what the next step is - I'm after the cell and the value, and the technique used to reach that conclusion?

I'm trying to learn the techniques - xwing, swordfish, colours - so am more interested in how to get the next step than in solving the puzzle. I've looked at the 3 techniques mentioned and none of them jump out at me. If it's a little more complicated than just saying the cell and value, feel free to elaborate.
Code: Select all
`. . 7 | 1 . 9 | . . .. 9 3 | 8 . 2 | 7 1 .. . . | . 7 . | . . .------+-------+------6 7 8 | . . . | . 2 4. . 1 | . . . | 5 . .9 5 . | 7 . . | . 6 3------+-------+------. . . | . 1 7 | . . .7 4 6 | 5 3 8 | 2 9 1. . . | 4 . 6 | . . .`

Candidates (let's see how I go at presenting these):
Code: Select all
`[2458]  [268]   [7]    | [1]     [456]   [9]    | [3468]  [3458]  [2568]  [45]    [9]     [3]    | [8]     [456]   [2]    | [7]     [1]     [56]    [12458] [1268]  [245]  | [36]    [7]     [345]  | [34689] [3458]  [25689] -----------------------+------------------------+-------------------------[6]     [7]     [8]    | [39]    [59]    [135]  | [19]    [2]     [4]     [234]   [23]    [1]    | [2369]  [24689] [34]   | [5]     [78]    [789]   [9]     [5]     [24]   | [7]     [248]   [14]   | [18]    [6]     [3]     -----------------------+------------------------+-------------------------[2358]  [238]   [259]  | [29]    [1]     [7]    | [3468]  [3458]  [568]   [7]     [4]     [6]    | [5]     [3]     [8]    | [2]     [9]     [1]     [12358] [1238]  [259]  | [4]     [29]    [6]    | [38]    [3578]  [578]   `
(whew! Note - the preview window is WIDER than the post window after it's submitted...)

Thanks - I'll get these ONE DAY!
Shazbot

Posts: 220
Joined: 24 September 2005

ok - after looking at this post http://forum.enjoysudoku.com/viewtopic.php?t=1778&highlight= I thought I MIGHT be able to try this here.

I compared R5C8 and R5C9 - [78] [789] and placed 9 in R5C9. I'm not REALLY sure why I did it (other than, well, let's see if it works, and if it doesn't, I've got it saved) or if it's using any kind of logic, but the puzzle just came together from there!

Can someone tell me if what I did was correct, and what's the reasoning behind it?
Shazbot

Posts: 220
Joined: 24 September 2005

oops - just found it - candidate 3's in r5c1 and r5c2 means I can eliminate 3 from r5c6. This also lets me complete the puzzle, and I actually understand the reasoning behind this one.

Still, this is feeling like a one-sided conversation. If anyone would like to advise on my possibly ill-chosen move in the previous post I'd be interested to see if DOES have a basis in logic, or if it was just a 50/50 and I chose the right one.
Shazbot

Posts: 220
Joined: 24 September 2005

Right, sorry no-ones taken notice, probably best to post in General/Puzzle next time.

I dubbed your puzzle in Simple Sudoku and the most obvious thing that leapt off the screen within literally 1 second (a lucky start for me) was that in Box 4, the 3's are confined to Row 5. This is referred to as Candidates locked in a Row and impiles that there can't be a three in Row 5 anywhere other than in Box 4. So cross out all other 3's in Row 5.

The puzzle totally falls apart after that.

shazbot wrote:oops - just found it - candidate 3's in r5c1 and r5c2 means I can eliminate 3 from r5c6. This also lets me complete the puzzle, and I actually understand the reasoning behind this one.

P.S. Sorry, didn't read that bit!

shazbot wrote:I compared R5C8 and R5C9 - [78] [789] and placed 9 in R5C9.

P.P.S. There is no reason to do that, it was a mistake. It just happened to be correct.
Karyobin

Posts: 396
Joined: 18 June 2005

thanks - the more I thought about it the more I convinced myself it was just a lucky guess.

My reference to a one-sided conversation was that I'd discovered my mistake fairly shortly after the original post - no-one had replied probably because I'm "on the other side of the world" (down under) and everyone else was probably at work or sleeping

Will keep it in mind though to check the other topics when I need help next.
Shazbot

Posts: 220
Joined: 24 September 2005

There are a few people here from the convict colony ( ). angusj is one, and there are many others, though the Stella is preventing me recalling them at the moment.
Karyobin

Posts: 396
Joined: 18 June 2005