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Quick puzzle
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gaby

Joined: 02 Jul 2005
Posts: 120
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PostPosted: Sat Feb 11, 2006 8:40 pm    Post subject: Quick puzzle Reply with quote

Hi,

Found me generator having trouble solving this one (taking a while, usually intense tabling is involved), and thought others might like to have a crack at this:

Code:

3---8--97
-2-67-4--
---------
-4-1----6
-5-----7-
1----4-5-
---------
--9-17-3-
63--2---5


How hard does your solver rate it? What techniques do you need to solve it?

Gaby
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Miles

Joined: 29 Dec 2005
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PostPosted: Sat Feb 11, 2006 10:08 pm    Post subject: Reply with quote

It needs more that XWing or Swordfish to be solve, at first sight - I didn't implement all kind of XWings or Swordfishes, so I don't know if it is strictely more or not -
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gaby

Joined: 02 Jul 2005
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PostPosted: Sat Feb 11, 2006 10:19 pm    Post subject: Reply with quote

Sudoku Susser rated it as requiring a number of nishio, and some tabling. Mine said pretty much the same.

Gaby
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vidarino

Joined: 10 Feb 2006
Posts: 38
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PostPosted: Sat Feb 11, 2006 10:51 pm    Post subject: Reply with quote

My solver cracks it with the help of a VWXYZ-Wing (The XYZ-Wing's big quintuple brother), a couple of Nice Loops and the use of Almost Locked Sets. So no guessing, forcing chains or Nishio required, but a pretty tough one anyhow.

Vidar
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rkral

Joined: 21 Oct 2005
Posts: 233
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PostPosted: Sat Feb 11, 2006 11:25 pm    Post subject: Reply with quote

My solver used multi-coloring twice, an x-wing, an almost-locked set xz-rule, and one (lucky) T&E guess that was followed by 42 naked singles.

I've seen some puzzles require more than 30 T&E guesses.
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tarek

Joined: 31 Dec 2005
Posts: 153
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PostPosted: Sun Feb 12, 2006 12:15 am    Post subject: Reply with quote

interesting puzzle,

This one (even without ALS) can be solved with simple discontinuous double implication chains.

The bit that was interesting is that there was 11 of them !!!

ALS seems to be the easist way around it.

Tarek
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daj95376

Joined: 05 Feb 2006
Posts: 349
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PostPosted: Sun Feb 12, 2006 1:22 am    Post subject: RE: Quick Puzzle Reply with quote

gaby,

I tried your puzzle with QQwing and here's the results.

Code:
The solution to the puzzle is unique.
Number of Inputs:                 24
Number of Singles:                44
Number of Hidden Singles:         12
Number of Naked Pairs:            0
Number of Hidden Pairs:           1
Number of Pointing Pairs/Triples: 1
Number of Box/Line Intersections: 1
Number of Guesses:                1
Number of Backtracks:             0
Difficulty:                       Expert


Note: I edited text fields and recompiled the source for QQwing.
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Ruud
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Joined: 17 Sep 2005
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PostPosted: Sun Feb 12, 2006 1:23 am    Post subject: Reply with quote

A Nightmare worthy Smile

I can put it up and see what the crowd does with it...

Ruud.
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rkral

Joined: 21 Oct 2005
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PostPosted: Sun Feb 12, 2006 1:37 am    Post subject: Reply with quote

Ruud wrote:
A Nightmare worthy Smile

I can put it up and see what the crowd does with it...

The puzzle I see requires nothing but singles. Is it April Fool's day? Laughing
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Ruud
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PostPosted: Sun Feb 12, 2006 1:56 am    Post subject: Reply with quote

Thank you for noticing!

QA seems to have missed this one. It is now fixed.

Ruud.
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rkral

Joined: 21 Oct 2005
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PostPosted: Sun Feb 12, 2006 11:16 am    Post subject: Reply with quote

gaby wrote:
Code:

 3..|.8.|.97
 .2.|67.|4..
 ...|...|...
 ---+---+---
 .4.|1..|..6
 .5.|...|.7.
 1..|..4|.5.
 ---+---+---
 ...|...|...
 ..9|.17|.3.
 63.|.2.|..5
rkral wrote:

My solver used multi-coloring twice, an x-wing, an almost-locked set xz-rule, and one (lucky) T&E guess that was followed by 42 naked singles.

This puzzle is a great example of the uselessness of ... naye, the insanity of ... giving solver results that include a T&E guess ... and the steps following that T&E guess.

Had I *disabled all logical techniques* and let the solver proceed using the same T&E algorithm, the puzzle would be *broken with one T&E step*. How useful would that be? Pretty useless IMO.

We'd have a much better picture of the logic capability of solvers if we reported the *number of remaining candidates at the time of the first T&E step*.

Ron


Last edited by rkral on Sun Feb 12, 2006 5:45 pm; edited 1 time in total
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gsf

Joined: 18 Aug 2005
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PostPosted: Sun Feb 12, 2006 2:58 pm    Post subject: Reply with quote

rkral wrote:

Had I *disabled all logical techniques* and let the solver proceed using the same T&E algorithm, the puzzle would be *solved with one T&E step*. How useful would that be? Pretty useless IMO.

ok, suppose that one t&e step fills in one hole (with the correct value no less)
how, without any "logical techniques", does that fill in the rest of the holes?
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rkral

Joined: 21 Oct 2005
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PostPosted: Sun Feb 12, 2006 4:46 pm    Post subject: Reply with quote

gsf wrote:
how, without any "logical techniques", does that fill in the rest of the holes?

Strictly speaking, it doesn't, of course. But I'm not counting cascading singles as a logical technique.
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gsf

Joined: 18 Aug 2005
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PostPosted: Sun Feb 12, 2006 4:56 pm    Post subject: Reply with quote

rkral wrote:
gsf wrote:
how, without any "logical techniques", does that fill in the rest of the holes?

Strictly speaking, it doesn't, of course. But I'm not counting cascading singles as a logical technique.

aha, well, to avoid confusion "singles" should be counted among the logical techniques
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rkral

Joined: 21 Oct 2005
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PostPosted: Sun Feb 12, 2006 5:49 pm    Post subject: Reply with quote

gsf wrote:
rkral wrote:
gsf wrote:
how, without any "logical techniques", does that fill in the rest of the holes?

Strictly speaking, it doesn't, of course. But I'm not counting cascading singles as a logical technique.

aha, well, to avoid confusion "singles" should be counted among the logical techniques

OK, for the purists among us, I've modified my original statement to say "broken" instead of "solved".

"Had I disabled all logical techniques and let the solver proceed using the same T&E algorithm, the puzzle would be broken with one T&E step."
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