The New Sudoku Players' Forum

by RW » Mon Oct 16, 2006 4:06 pm

So, you don't like forcing chains, but maybe you'll find some pleasure in this wheel of fortune:

Code: Select all: ...|...|... ..9|5.7|6.. .45|8.6|32. ---+---+--- .68|3.1|54. ...|...|... .93|2.4|71. ---+---+--- .34|6.8|15. ..1|4.9|8.. ...|...|...

wapati wrote:Is there a puzzle type (eg BUG) where forcing chains are just the long way around?

Not puzzle type, but plenty of puzzles when it comes to uniqueness technique. Just posted a puzzle here that requires 5 forcing chains in SE, but only a glance at the starting grid if you know the right technique!

RW

by **wapati** » Mon Oct 16, 2006 4:59 pm

RW wrote:So, you don't like forcing chains, but maybe you'll find some pleasure in this wheel of fortune:
RW

Brilliant puzzle!! Thanks

by **wapati** » Mon Oct 16, 2006 5:02 pm

ravel wrote:
Carcul wrote:
Wapati wrote:Hairy, below chins
This puzzle is too easy:
Already forgot the remote pairs Wapati ?

I'll admit to using them if I trip over them but I bet that people who like chains spot them quicker! :idea:

by **Carcul** » Mon Oct 16, 2006 6:16 pm

Code: Select all: *-------------------------------------------------------------------* | 13678 78 67 | 19 234 23 | 49 79 5 | | 13 2 9 | 5 34 7 | 6 8 14 | | 17 4 5 | 8 19 6 | 3 2 179 | |---------------------+--------------------+------------------------| | 27 6 8 | 3 79 1 | 5 4 29 | | 4 1 27 | 79 68 5 | 29 36 368 | | 5 9 3 | 2 68 4 | 7 1 68 | |---------------------+--------------------+------------------------| | 279 3 4 | 6 27 8 | 1 5 279 | | 267 57 1 | 4 2357 9 | 8 367 2367 | | 26789 578 267 | 17 12357 23 | 249 3679 234679 | *-------------------------------------------------------------------*

[r3c9]=7=[r3c1]-7-[r4c1]-2-[r4c9]-9-[r3c9],

=> r3c9<>9 solving the puzzle.

Forcing chains often provide shorter solutions. In fact, if I were Finnish I would say that solving this puzzle without forcing chains would be "kiivetä perse edellä puuhun".

Carcul

by RW » Mon Oct 16, 2006 7:00 pm

carcul wrote:In fact, if I were Finnish I would say that solving this puzzle without forcing chains would be "kiivetä perse edellä puuhun".

It's actually very fun to "kiivetä perse edellä puuhun". Have you ever tried it? We had a sergeant in the army who made us learn the noble skill and after that I've practised it a few times in street lights on my way home from the bar.

It's great for your abdominals also!

RW

by **Ocean** » Mon Oct 16, 2006 10:25 pm

Carcul wrote:[r3c9]=7=[r3c1]-7-[r4c1]-2-[r4c9]-9-[r3c9],

=> r3c9<>9 solving the puzzle.

Even simpler is this XY-wing:

-7-[r3c1]-1-[r3c5]-9-[r4c5]-7-,
=> r4c1<>7 solving the puzzle.

Code: Select all: *-------------------------------------------------------------------* | 13678 78 67 | 19 234 23 | 49 79 5 | | 13 2 9 | 5 34 7 | 6 8 14 | |#17 4 5 | 8 #19 6 | 3 2 179 | |---------------------+--------------------+------------------------| |*27 6 8 | 3 #79 1 | 5 4 29 | | 4 1 27 | 79 68 5 | 29 36 368 | | 5 9 3 | 2 68 4 | 7 1 68 | |---------------------+--------------------+------------------------| | 279 3 4 | 6 27 8 | 1 5 279 | | 267 57 1 | 4 2357 9 | 8 367 2367 | | 26789 578 267 | 17 12357 23 | 249 3679 234679 | *-------------------------------------------------------------------*

Carcul wrote:Forcing chains often provide shorter solutions. In fact, if I were Finnish I would say that solving this puzzle without forcing chains would be "kiivetä perse edellä puuhun".

In general I would agree to this observation - a few hard steps can often replace several less hard steps. But would like to add: Sometimes it can be a challenge to pick techniques that immediately solve the puzzle. There are many blind paths - they don't hurt, they "waste" time, but they might lead us through beautiful landscape. When alternative short paths are available, it's also a challenge to select the simplest of those paths.

by **wapati** » Tue Oct 17, 2006 4:21 am

Ocean wrote:Sometimes it can be a challenge to pick techniques that immediately solve the puzzle. There are many blind paths - they don't hurt, they "waste" time, but they might lead us through beautiful landscape. When alternative short paths are available, it's also a challenge to select the simplest of those paths.

Well said. Two shortcuts I often see are URs and grouped x-wings.

What kills me is that most swordfish I find are ones that are already "done", no eliminations.

by **wapati** » Tue Oct 17, 2006 5:36 am

This has some humour!

Code: Select all: ..8...6.. 561...934 .3..9..2. ....2.... 27.....89 ..5...4.. ....4.... 8.......1 7..239..8

by **wapati** » Tue Oct 17, 2006 5:46 am

This too!

(Daj, I was teasing.)

Code: Select all: 9 . . | . . 2 | . . 5 . . 2 | . 3 . | . 8 . . 4 7 | . 5 . | . . . --------------------- . . . | . . . | . . 1 . 3 6 | . 4 . | . . . 8 . . | . . . | 4 3 9 --------------------- . . . | . . 5 | 9 2 . . 2 . | . . 7 | 8 . 6 4 . . | 6 . 8 | . 1 .

by **Carcul** » Tue Oct 17, 2006 8:52 am

Ocean wrote:Even simpler is this XY-wing:

Why simpler? The number of links is the same.

Wapati wrote:This has some humour!

Code: Select all: *-------------------------------------------------------------------* | 9 2 8 | 34 5 34 | 6 1 7 | | 5 6 1 | 78 78 2 | 9 3 4 | | 4 3 7 | 16 9 16 | 8 2 5 | |----------------------+-----------------------+--------------------| | 136 489 3469 | 346789 2 34678 | 137 5 36 | | 2 7 346 | 3456 16 3456 | 13 8 9 | | 136 89 5 | 36789 1678 3678 | 4 67 2 | |----------------------+-----------------------+--------------------| | 36 5 29 | 18 4 18 | 27 79 36 | | 8 49 23 | 567 67 567 | 23 49 1 | | 7 1 46 | 2 3 9 | 5 46 8 | *-------------------------------------------------------------------*

[r9c8]=6=[r6c8](-6-[r6c1])-6-[r4c9]-3-[r5c7]-1-[r5c5]=1=[r6c5]-
-1-[(r6c1)]-3-[r7c1]-6-[r9c3]=6=[r9c8],

=> r9c8=6 solving the puzzle.

Wapati wrote:This too!

Code: Select all: *-------------------------------------------* | 9 8 13 | 17 67 2 | 136 4 5 | | 5 16 2 | 9 3 4 | 16 8 7 | | 136 4 7 | 8 5 16 | 136 9 2 | |--------------+--------------+-------------| | 27 9 4 | 57 8 3 | 25 6 1 | | 12 3 6 | 15 4 9 | 25 7 8 | | 8 17 5 | 2 67 16 | 4 3 9 | |--------------+--------------+-------------| | 67 67 8 | 3 1 5 | 9 2 4 | | 13 2 13 | 4 9 7 | 8 5 6 | | 4 5 9 | 6 2 8 | 7 1 3 | *-------------------------------------------*

[r3c7]=1=[r8c1]=3=[r3c1]-3-[r3c7], => r3c7<>3 solving the puzzle.

Carcul

by **Carcul** » Tue Oct 17, 2006 9:24 am

RW wrote:It's actually very fun to "kiivetä perse edellä puuhun". Have you ever tried it? We had a sergeant in the army who made us learn the noble skill and after that I've practised it a few times in street lights on my way home from the bar. It's great for your abdominals also!

No, I have never tried it, but if it's great for the abdominals, then I will consider start doing it.

Carcul

by **ravel** » Tue Oct 17, 2006 11:07 am

Mhm, for the others:
hymyillä kuin hangon keksi.

by **wapati** » Tue Oct 17, 2006 2:32 pm

This has lots of Turbots or lots of ERs, depending on the path you take?
The swordfish may be missed.

Code: Select all: 2 8 . | . . 3 | . 4 7 7 . 1 | 9 . . | . 3 . . 3 . | 6 7 . | . . 2 --------------------- . 4 5 | . . . | 8 . 1 . . 8 | . 1 . | . 9 . 3 . . | . . 5 | . . . --------------------- . . . | 5 . . | . . . 8 5 . | . 3 . | . . . 1 . 3 | 7 . . | . . .

by **wapati** » Tue Oct 17, 2006 3:20 pm

I had troubles with this one. I do like it when URs are required rather than shortcuts!

Code: Select all: . 7 . | . . . | 9 . 3 . 8 . | . 2 . | 1 . . . 1 . | 3 . . | . 5 6 --------------------- 5 . . | . . 1 | . . . . . 7 | . 3 . | . 9 . . . . | 9 . . | 6 . . --------------------- 2 . . | . 7 . | . . . . 4 . | . . . | 2 3 8 8 . 1 | . . 3 | . . .

by **wapati** » Tue Oct 17, 2006 3:44 pm

ER to the rescue. APE can be used, apparently, but I don't know it.
Fortunately there is a work around using grouped x and ER. phew!

Code: Select all: . 4 . | . . 8 | 9 2 . . 6 8 | . . . | . . 4 9 . . | . . . | . . 8 --------------------- . . . | . 8 . | . . 9 . . 7 | 6 . 9 | . . . 3 . 4 | . 5 . | . . . --------------------- . . . | 4 1 . | . 5 . 4 . . | . . . | . 9 6 . 2 . | 7 . . | 3 . .

The New Sudoku Players' Forum

Fun puzzle. So many methods to solve. No CHAINS required.

Wheel of Fortune

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Re: Wheel of Fortune