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Since there has been interesting strategy discussion on these puzzles and by popular request, I have opened an archive on the last thirty weeks. The discussion section is open for continued posting.
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by:Stefan

 

is.gd/Xstefan438


 

by: Bansalsaab

 
 
Thans Stefan for this one. Mostly CEs but doesnt solve easily.

 

by: Andy B.

 
 
@Stefan
a real masterpiece x-puzzle. No chain but really the whole toolbox for an x-puzzle. I really liked it! Thank you for your work on that!

 

by: jgrab

 
 
Thanks, very laborious CE.

 

by: Christoph

 
 
Very nice X-puzzle, Stefan.
The pair B2/C3 was relatively easy to define.
Then: CE and standard tools. I liked it really.


 

by: Pets

Add to this thread
 
Thank you Stefan - brilliant!

by:hoke

 
is.gd/hoke438

 

by: Christoph

 
 
hoke, after two not successful attempts (conflict setti 4), could it be that your pattern is not complete (what about a 4 in A6 ?) ?

 

by: Jan

 
 
No, this is solveable and has just one solution.

With a lot of CE you can solve 18 cells. There is also a setti consideration of a type mentioned recently; however, I don't know whether that's really needed for the solution.

The next step is to realize that in a certain row, one digit having two candidates is a must. One candidate leads to a contradiction (for the moment after a long chain); choosing the other candidate quickly solves another eight cells. At this point, an CE in a row generates a large gap which solves.

 

by: Jan

 
 
Oh, and the wrong candidate I mentioned does indeed generate a situation where you run out of 4s, i.e., a setti 4 contradiction.

 

by: Christoph

 
 
Sorry, I shall check once more. Perhaps I have overlooked something.

 

by: Christoph

 
 
ok, I checked once more. There is no need for a 4 in A6, however 4 in A6 would result in the same solution.
Sorry, for creating potential confusion.
Thanks, hoke.

 

by: hoke

 
 
@Christoph: The pattern is a modification from the puzzle in the SZ of Friday last week, a result of testing my program for redundancy removal. It contained a 4 in A6. How did you guess that?

 

by: Christoph

Add to this thread
 
@hoke: in my first two attempts a had a silly failure in the left top corner, respectively in row A.
Thus, in order to avoid another fruitless attempt,
I wanted to check row A in your "solution". Starting to check this row, I was confronted with your indication of 4 in the black cell A6, which confused me. Thus the 4 in A6 was nor a guess, nor the consequence of careful deliberation.

by:Andrejs

Reply to this post
I chose one of two alternative possibilitys, which led to a complete solution. In order to use setti, I found the rows F sure digits by written all the possible combinations of compartments digits. Maybe I could handle more rationally?



by:morl

 
is.gd/morl_438_2

 

by: Fab

 
 
Fiou, finally finished it... Everytime I would start to despair I would finally find a new pattern. Heavy on Fishes and settis for me. At some point I failed to see an obvious CE which unlocks many things.
Made me use my whole toolbox, which is nice.

 

by: Christoph

 
 
very hard. A head chain solves hi/lo in row J (wrong fig in J8 creates a conflict in col 5).
Then I needed a contradiction chain to find the position of 4 in col 1. Even the rest was a challenge.

 

by: Harm

 
 
Thank you morl - hard, but very nice. Head chains on row J like Christoph and on GH7 (no 1 possible) were the keys. Settis and several x-wings afterwards.

 

by: hone

 
 
Thank you, morl.

An xwing and 2 settis; no chains needed.
A good example of an early xwing, which are hard to detect.

 

by: Christoph

 
 
I have checked it once more. Adfter solving hi/lo in J as described originally, I managed now to solve this very nice puzzle without further chaining. Originally I had overlooked a col-xwing 3, followed by two more wings and setti 2.

 

by: Jan

 
 
I'm with hone on this one: A hard to see x-wing generates an elimination in column 9 that breaks the symmetry there. After that, I used the x-wing probably equivalent to the first setti hone used, which however solves with just another single.

 

by: jgrab

 
 
Thanks to all! After I saw the hard-to-find xwing, everything went out smoothly. But I would never have spotted for it without advice to do so.

 

by: Andy B.

Add to this thread
 
thanks morl. Great puzzle!!!

by:hone

 
is.gd/hone438_Lupus

 

by: Jan

 
 
Fairly easy - took me 17' by hand - but nonetheless very nice in its development! One large wing in one part of board and several overlapping ones elsewhere bring you towards the solution step by step. Watch you singles!

 

by: jgrab

 
 
Thanks, very nice! After a 4x4 wing, many doubles appear and lead you throgh the game. Used some Settis towards the end.

 

by: Fab

 
 
Nice!
I didnt see the 4x4 wing, but some SI in the upper right. Afterwards, a setti and several X-wings, watching out for singles.
I used an UR too, but for the fun as it was very probably unnecessary.

 

by: Christoph

Add to this thread
 
I used setti 6, 2 URs, x-wing 9, x-wing 7, 4-wing on 5, singles.
Thanks, hone.

by:kolumbus

 
just CE, some singles and one x-wing ... maybe anyone has an extra puzzle in stock?

 

by: Jan

 
 
But the first single needs a large gap to appear, so it's not quite that simple!

 

by: kolumbus

Add to this thread
 
@Jan: for me excluding large gaps is part of careful elimination ...

by:morl

 
is.gd/morl_438_1

 

by: kolumbus

 
 
thanks a lot, morl, our posts overlapped

 

by: kolumbus

 
 
hard nut, very fine puzzle; finally a head chain starting from E7 brought the solution, thanks again.

 

by: Christoph

 
 
I have failed so far to find a reasonable way to solve this puzzle.

 

by: Christoph

 
 
ok, I got it. I had not seen the single 5 in C9.
Testing the wrong candidaate in E6 leads to a conflict in G3-G7
(head chain), as already mentioned by kolumbus.
Thanks , morl, for this nice challenge.

 

by: Christoph

 
 
Sorry, TYPO: ,,,correct: ...the single 5 in E9.

 

by: Christoph

 
 
second TYPO: E7 instead of E6. Sorry.

 

by: jgrab

Add to this thread
 
Very nice. Thanks for the puzzle, and for the hints.



Article created on 27-June-2010.
This page was last modified on 17-April-2011.
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  • 38' no guess but keeping a sharp eye
       - Tosthene - 2 hours ago
  • 43' at second attempt a nice one
       - bsz - 2 hours ago
  • 48 Min. Guess on Row D. Otherwise, very straight and simple.
       - D-Day - 2 days ago
  • 1h14, with a lucky guess on D3
       - Fleurette - 2 days ago
  • 21 on second attempt, unusually fast for me, the trick is the c-row decision
       - emil - 2 days ago
  • mein erstes Extrem Str8ts 52:10
       - Filip - 2 days ago
  • beim 2ten Versuch in einer Stunde gelöst
       - wjanet - 3 days ago
  • 38 min
       - mv - 3 days ago
  • 28', looking closely
       - joeB - 3 days ago
  • 46` - only logic
       - ihgs - 3 days ago
  • 28:30 1 in row D is the key; finishing with settis; a good one!!
       - joe reitzl - 4 days ago
  • 50' - took me quite a while to see the obvious in Col 2
       - selecti - 4 days ago
  • Can do in about 20 minutes if you notice all the singles and use x-wings.
       - JT - 5 days ago
  • 30min;Boerny was right
       - Hildi - 5 days ago
  • 25 min
       - 7iron - 5 days ago
  • 16 min.
       - Katjulik - 5 days ago
  • 44 min. - like un: 1 in D is the key, yet w.o. guess
       - Boerny - 5 days ago
  • 26' settis, x-wings, singles
       - Greg - 6 days ago
  • 52 min
       - Kurt - 6 days ago
  • 1h, checking options in C2 was my key
       - Cosmanita - 6 days ago
  • 30:55 - Settis, logic, extremely watch for singles - with the aid of solver support runs that's was needed. An elegant yet mind boggling one
       - Korbinian Bär - 6 days ago
  • 1h, with hint, very nice
       - chris - 6 days ago
  • Not sure what I missed but I didn't find this one so easy.
       - mparmen - 6 days ago
  • 16 min - nice and not too difficult
       - Susan - 6 days ago
  • 1 in row D is the key; could not find a logical solution, needed to guess :-(
       - un - 6 days ago
  • nice one, on sec. attempt 12 min
       - easydoesit - 6 days ago
  • 16 min 1 in D is the key
       - poblid - 6 days ago
  • Sorry, D3 of course!
       - Jan - 6 days ago
  • 17' manually, but on the second attempt - interesting single solves D4, and one x-wing is required.
       - Jan - 6 days ago
  • D3 is the key
       - Berndie - 6 days ago