Big fish

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Big fish

Postby wapati » Sat May 22, 2010 3:10 pm

Wapati here,

I posted puzzles needing no chains for a spell.

I have better understanding now and admit that chains are hard to avoid. :)

I now prefer short chains, I guess I always did. I still really like swordfish and jellyfish.

I have resumed posting puzzles that I think are fun. Big fish, maybe short chains, will be involved.

Great to be back in the hands of people who care about Sudoku, huge thanks to Jason and GSF.

I use HoDoKu, JSudoku and SudoCue every day. There are other fine solvers that I use less often.
I admire and enjoy the work all people who create fine apps and I thank them.

I do most solving with pencil and paper but my selection of which puzzles is determined using software.
It is great that I have options when/if I get a brain clamp!
Last edited by wapati on Sun May 23, 2010 5:08 am, edited 13 times in total.
wapati
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Location: Brampton, Ontario, Canada

Short form of these puzzles.

Postby wapati » Sat May 22, 2010 3:13 pm


    ......7.....9...5.5.84.29.39....6..71...7...98..3....27.92.54.8.5...3.....3......
    .61...42..4.73......5.261..5..6.4..8.........6..1.3..2..934.2......19.4..58...93.
    ...78..........1539....14..3..9...12.........78...6..4..16....7835..........43...
    21.5.....8...74.....73.1..668....2...31...64...2....353..4.25.....69...2.....7.14
    .931..8..........9.....673..5.6..18.1..7.3..5.34..1.2..298.....8..........6..921.

    .....97....93...65....7.3.117......8.9.567.3.3......579.7.5....52...48....47.....
    96....17..8...432..3.6....8...7856.............6342...4....6.8..152...6..28....15
    4..9.86..93...........27.38.8...9...1.......5...1...4.86.74...........86..56.1..7
Last edited by wapati on Wed Jun 02, 2010 12:36 am, edited 11 times in total.
wapati
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#1

Postby wapati » Sat May 22, 2010 3:23 pm

#1
Code: Select all
. . .|. . .|7 . .
. . .|9 . .|. 5 .
5 . 8|4 . 2|9 . 3
-----+-----+-----
9 . .|. . 6|. . 7
1 . .|. 7 .|. . 9
8 . .|3 . .|. . 2
-----+-----+-----
7 . 9|2 . 5|4 . 8
. 5 .|. . 3|. . .
. . 3|. . .|. . .
Last edited by wapati on Wed May 26, 2010 3:45 pm, edited 3 times in total.
wapati
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#2

Postby wapati » Sat May 22, 2010 3:30 pm

It would be good to know about hidden URs, else, perhaps you like long xy-chains? :lol:
#2
Code: Select all
]. 6 1|. . .|4 2 .
. 4 .|7 3 .|. . .
. . 5|. 2 6|1 . .
-----+-----+-----
5 . .|6 . 4|. . 8
. . .|. . .|. . .
6 . .|1 . 3|. . 2
-----+-----+-----
. . 9|3 4 .|2 . .
. . .|. 1 9|. 4 .
. 5 8|. . .|9 3 .
Last edited by wapati on Wed May 26, 2010 3:46 pm, edited 4 times in total.
wapati
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#3

Postby wapati » Sun May 23, 2010 4:46 am

There is stuff here. Sashimi sword is why I like this one.
Towards finished? There is an almost W-wing where you need to see that a pair ( 56 46 ) can be used as a ( 45 ).
Seems easy to me. 8-)

#3
Code: Select all
. . .|7 8 .|. . .
. . .|. . .|1 5 3
9 . .|. . 1|4 . .
-----+-----+-----
3 . .|9 . .|. 1 2
. . .|. . .|. . .
7 8 .|. . 6|. . 4
-----+-----+-----
. . 1|6 . .|. . 7
8 3 5|. . .|. . .
. . .|. 4 3|. . .
Last edited by wapati on Thu May 27, 2010 4:34 am, edited 2 times in total.
wapati
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#4

Postby wapati » Mon May 24, 2010 12:30 am

Hidden UR, swordfish.

#4
Code: Select all
2 1 .|5 . .|. . .
8 . .|. 7 4|. . .
. . 7|3 . 1|. . 6
-----+-----+-----
6 8 .|. . .|2 . .
. 3 1|. . .|6 4 .
. . 2|. . .|. 3 5
-----+-----+-----
3 . .|4 . 2|5 . .
. . .|6 9 .|. . 2
. . .|. . 7|. 1 4
Last edited by wapati on Thu May 27, 2010 4:34 am, edited 2 times in total.
wapati
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Location: Brampton, Ontario, Canada

Re: Big Fishies

Postby eleven » Tue May 25, 2010 10:52 am

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

Hi wapati,
it seems that there are not much players around here :)

As a start to your first one (please give them numbers for references), its very easy and does not need any fish.
After singles:
Code: Select all
3 9 .|. . .|7 2 *
. . .|9 3 7|8 5 *
5 7 8|4 # 2|9 # 3
-----+-----+-----
9 . .|. 2 6|. . 7
1 . .|. 7 .|. . 9
8 . 7|3 . .|. . 2
-----+-----+-----
7 # 9|2 # 5|4 3 8
. 5 .|. . 3|. . #
. 8 3|. . .|. . 5

The marked cells can only be 16, so there is a remote pair r7c2-r3c8 and also r7c2-r8c9 (via r23c9). Thus r8c3 cannot be 16, and the 1 in r7c2 solves it with singles again.

[Added:]
Last puzzle (#4):
After a few singles:
Code: Select all
2 1 .|5 # #|* * *
8 6 .|. 7 4|. h .
. . 7|3 . 1|- h 6
-----+-----+-----
6 8 .|. . .|2 . .
. 3 1|. . .|6 4 .
. . 2|. # #|* 3 5
-----+-----+-----
3 . .|4 . 2|5 . .
1 . .|6 9 .|. . 2
. 2 6|8 . 7|. 1 4

The #-cells form a possibly deadly pattern (UR) for 6 and 8. Since 6 cannot be elsewhere in the 2 rows, either 8 must be in r1c789 or in r6c7.
In both cases it cannot be in r3c7. Since there is a hidden pair 25 in r23c8, r3c5 must be 8 - only singles left.
eleven
 
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Joined: 10 February 2008

#5

Postby wapati » Wed May 26, 2010 4:22 am

Interesting solving methods, eleven. Thanks for showing them!


Finned Swordfish. #5

Code: Select all
. 9 3|1 . .|8 . .
. . .|. . .|. . 9
. . .|. . 6|7 3 .
-----+-----+-----
. 5 .|6 . .|1 8 .
1 . .|7 . 3|. . 5
. 3 4|. . 1|. 2 .
-----+-----+-----
. 2 9|8 . .|. . .
8 . .|. . .|. . .
. . 6|. . 9|2 1 .
Last edited by wapati on Thu May 27, 2010 4:35 am, edited 1 time in total.
wapati
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Re: Big fish

Postby eleven » Wed May 26, 2010 7:55 am

This time a dirty chain :geek:

After singles:
Code: Select all
  .   9   3 | 1  .  . | 8  .  2
  .   .   . | .  .  8 | .  .  9
  . @48   . | 9  .  6 | 7  3  1
------------+---------+--------
#279  5 #27 | 6  .*24 | 1  8  .
  1 *68  28 | 7 29  3 | .  .  5
*69   3   4 | 5  8  1 |69  2  7
------------+---------+--------
 @4+  2   9 | 8  1 *4+|35 57  6
  8  17   . |23  6  . | .  .  4
  . -47   6 |34  .  9 | 2  1  8

Arans "hidden pair":
Either there is a pair 27 in r4c13, implying 4 in r4c6
Or there is a 9 in r4c1, leading to a 4 in r3c2 via r6c1=6,r5c2=8
So we have r3c2=4 or r4c6=4, which also implies r7c1=4 (via r7c6<>4)
And we can eliminate 4 in r9c2 (and r123c1).
eleven
 
Posts: 1563
Joined: 10 February 2008

Finned Jelly.

Postby wapati » Thu May 27, 2010 2:23 pm

Finned Jelly.

#6
Code: Select all
. . .|. . 9|7 . .
. . 9|3 . .|. 6 5
. . .|. 7 .|3 . 1
-----+-----+-----
1 7 .|. . .|. . 8
. 9 .|5 6 7|. 3 .
3 . .|. . .|. 5 7
-----+-----+-----
9 . 7|. 5 .|. . .
5 2 .|. . 4|8 . .
. . 4|7 . .|. . .
wapati
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Location: Brampton, Ontario, Canada

Finned Swordfish

Postby wapati » Sat May 29, 2010 2:14 am

Finned sword

#7

Code: Select all
9 6 .|. . .|1 7 .
. 8 .|. . 4|3 2 .
. 3 .|6 . .|. . 8
-----+-----+-----
. . .|7 8 5|6 . .
. . .|. . .|. . .
. . 6|3 4 2|. . .
-----+-----+-----
4 . .|. . 6|. 8 .
. 1 5|2 . .|. 6 .
. 2 8|. . .|. 1 5
wapati
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Re: Big fish

Postby eleven » Sat May 29, 2010 11:01 pm

Puzzle 6:

With singles and box-line for 6 in c4 you get here:
Code: Select all
    . 5 3 | - . 9 | 7 8 #
    7 1 9 | 3 . . | . 6 5
    x x x | - 7 5 | 3 9 1
    ------+-------+------
    1 7 5 | # 9 3 | 6 # 8
    . 9 . | 5 6 7 | 1 3 #
    3 . . | . . . | 9 5 7
    ------+-------+------
    9 . 7 | . 5 . | . . 3
    5 2 1 | 9 3 4 | 8 7 6
    . . 4 | 7 . . | 5 . 9

The 4 # marked cells only can be 24, thus there is a remote pair in r4c4 and r1c9, eliminating 24 in r1c4 (leaving 16).
But there is more: 2/4 in r1c9 also implies 2/4 in r3c123. So you can eliminate 24 also in r3c4, leaving 6 alone, because the 8 also is locked in r3c123.
Singles after that move.


Puzzle 7 was a long one for me.

After singles:
Code: Select all
    9 6 2|8 5 3|1 7 4
    5 8 .|. . 4|3 2 6
    # 3 4|6 2 @|p p 8
    -----+-----+-----
    . . .|7 8 5|6 . .
    . . .|. 6 .|. . .
    . . 6|3 4 2|° p .
    -----+-----+-----
    4 . .|5 1 6|. 8 .
    - 1 5|2 @ 8|4 6 .
    6 2 8|4 3 #|. 1 5

In row 3 17 is left in the marked cells. With the strong link for 7 in box 8 we have a kite eliminating 7 in r8c1, leaving 3.
Also note the UR 59 (p) in r36c78 leaving 78 in r6c7.
Code: Select all
    9 6 2|8 5 3|1 7 4
    5 8 @|. # 4|3 2 6
    # 3 4|6 2 @|. . 8
    -----+-----+-----
   12 . .|7 8 5|6 . .
   78 . .|. 6 .|. . 27
    . . 6|3 4 2|78. .
    -----+-----+-----
    4 . .|5 1 6|2 8 3
    3 1 5|2 @ 8|4 6 #
    6 2 8|4 3 #|@ 1 5

Now we can find more with those 7's. With the strong links either all # cells must be 7 or all @ cells.
So one of r1c3 and r9c7 must be 7, implying r5c1=8 and r6c7=8 resp. Since one leads to the other, both must be true.
Since r3c1=17, either r3c1=1 implying r4c1=2 or (r3c1 and) r8c9=7 implying r5c9=2. Again one 2 leads to the other.

This gives
Code: Select all
    9 6 2|8 5 3|1 7 4
    5 8 @|. # 4|3 2 6
    # 3 4|6 2 @|. . 8
    -----+-----+-----
    2 . .|7 8 5|6 . .
    8 . .|. 6 .|# . 2
    @ . 6|3 4 2|8 . @
    -----+-----+-----
    4 . .|5 1 6|2 8 3
    3 1 5|2 @ 8|4 6 #
    6 2 8|4 3 #|@ 1 5

and new strong links for 7 in columns 1, 7 and 9. Now the @-marked cells cannot be 7, because there are two in row 6.
eleven
 
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Joined: 10 February 2008

Re: Big fish

Postby aran » Tue Jun 01, 2010 11:49 am

Eleven in #7 from the position just after the UR move <59>, one could use this :
9r2c5+7r8c9 impossible (=>r8c5 empty)
=>7r2c3+9r4c9 impossible (=>previous)
=>1r2c3 or pair12r4c19 must be true
so r4c3 <1> therefore r3c1=7.
Even though this is really hidden pair logic, this expression of it might be more in your line of thought.
aran
 
Posts: 334
Joined: 02 March 2007

Re: Big fish

Postby eleven » Tue Jun 01, 2010 1:18 pm

Nice, i had missed the implication r4c19=12 -> r2c3=1
Both r4c9=9 and r2c3=1 imply 7 in a #-cell.
eleven
 
Posts: 1563
Joined: 10 February 2008

Finned Jelly. #8

Postby wapati » Wed Jun 02, 2010 12:36 am

Interesting finned jelly, it can be seen differently at right angles.
(You often see a swordfish instead. )
Use it, it is a shortcut. Added to a remote pair you can solve this.

There are lots of herring. :-)

#8
Code: Select all
4 . .|9 . 8|6 . .
9 3 .|. . .|. . .
. . .|. 2 7|. 3 8
-----+-----+-----
. 8 .|. . 9|. . .
1 . .|. . .|. . 5
. . .|1 . .|. 4 .
-----+-----+-----
8 6 .|7 4 .|. . .
. . .|. . .|. 8 6
. . 5|6 . 1|. . 7
Last edited by wapati on Mon Jun 07, 2010 5:14 am, edited 1 time in total.
wapati
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