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MM 1568, 10-25-09

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storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Sun Oct 25, 2009 4:40 pm Post subject: MM 1568, 10-25-09

080000020506700000030100054005030000410000062000060100170003080000008413090000070

Code:

+-------+-------+-------+
| . 8 . | . . . | . 2 . |
| 5 . 6 | 7 . . | . . . |
| . 3 . | 1 . . | . 5 4 |
+-------+-------+-------+
| . . 5 | . 3 . | . . . |
| 4 1 . | . . . | . 6 2 |
| . . . | . 6 . | 1 . . |
+-------+-------+-------+
| 1 7 . | . . 3 | . 8 . |
| . . . | . . 8 | 4 1 3 |
| . 9 . | . . . | . 7 . |
+-------+-------+-------+

open in draw/play page

open in andrew stuarts online solver
-----
this is the Vanhegan/playr Extreme which isn't extreme. its a VH

002905000070360000840010000016070002003000700200030190000040053000021070000803200

Code:

+-------+-------+-------+
| . . 2 | 9 . 5 | . . . |
| . 7 . | 3 6 . | . . . |
| 8 4 . | . 1 . | . . . |
+-------+-------+-------+
| . 1 6 | . 7 . | . . 2 |
| . . 3 | . . . | 7 . . |
| 2 . . | . 3 . | 1 9 . |
+-------+-------+-------+
| . . . | . 4 . | . 5 3 |
| . . . | . 2 1 | . 7 . |
| . . . | 8 . 3 | 2 . . |
+-------+-------+-------+

Open in draw/play page

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun Oct 25, 2009 6:49 pm Post subject: Re: MM 1568, 10-25-09

storm_norm wrote:

080000020506700000030100054005030000410000062000060100170003080000008413090000070

1-stepper:

Code:

(7=9)r4c7 - r6c8 = r2c8 - (9=67)r1c79 => r3c7<>7
+--------------------------------------------------------------+
| 79 8 1 | 3 4 5 | 679 2 679 |
| 5 4 6 | 7 289 29 | 389 39 1 |
| 2 3 79 | 1 89 6 | 789 5 4 |
|--------------------+--------------------+--------------------|
| 789 6 5 | 2 3 1 | 79 4 789 |
| 4 1 3789 | 58 59 79 | 3579 6 2 |
| 3789 2 3789 | 458 6 479 | 1 39 5789 |
|--------------------+--------------------+--------------------|
| 1 7 4 | 56 25 3 | 2569 8 569 |
| 6 5 2 | 9 7 8 | 4 1 3 |
| 38 9 38 | 456 1 24 | 256 7 56 |
+--------------------------------------------------------------+
# 58 eliminations remain

arkietech

Joined: 31 Jul 2008
Posts: 1834
Location: Northwest Arkansas USA

Posted: Sun Oct 25, 2009 7:03 pm Post subject: Re: MM 1568, 10-25-09

storm_norm wrote:

080000020506700000030100054005030000410000062000060100170003080000008413090000070

Quote:

w-wing 97 did it for me.

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Mon Oct 26, 2009 8:39 pm Post subject:

found a one stepper for the playr.extreme.

Code:

+-------------------+-----------------+-----------------+
| 36 36 2 | 9 8 5 | 4 1 7 |
| 159 7 159 | 3 6 4 | 589 2 589 |
| 8 4 59 | 2 1 7 | 3569 36 569 |
+-------------------+-----------------+-----------------+
| (459) 1 6 | (45) 7 (89) | 35 348 2 |
| 459 589 3 | 1 59 2 | 7 468 456 |
| 2 (58) 7 | 456 3 -8(6) | 1 9 45 |
+-------------------+-----------------+-----------------+
| 169 2 189 | 7 4 9(6) | 689 5 3 |
| 3569 3569 4589 | (56) 2 1 | 689 7 4689 |
| 7 569 459 | 8 59 3 | 2 46 1 |
+-------------------+-----------------+-----------------+

its a net
but it can be viewed as a finned xy-wing
[(8=9)r4c6 - fin(9=5)r4c1 - (5=8)r6c2] = (4)r4c1 - (4=5)r4c4 - (5=6)r8c4 - (6)r7c6 = (6)r4c6; r4c6 <> 8

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Mon Oct 26, 2009 11:31 pm Post subject:

storm_norm wrote:

found a one stepper for the playr.extreme.

Code:

its a net
but it can be viewed as a finned xy-wing
[(8=9)r4c6 - fin(9=5)r4c1 - (5=8)r6c2] = (4)r4c1 - (4=5)r4c4 - (5=6)r8c4 - (6)r7c6 = (6)r4c6; r4c6 <> 8

Norm, do you have a typo? It makes me nervous to see two strong links back-to-back.

Code:

... - (5=8)r6c2] = (4)r4c1 - ...
^ ------ ^

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Mon Oct 26, 2009 11:38 pm Post subject:

not a typo either the AIC inside the square brackets is true or the 4 is true in r4c1.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Oct 27, 2009 1:25 am Post subject:

storm_norm wrote:

not a typo
either the AIC inside the square brackets is true or the 4 is true in r4c1.

Hmmm! I think that I'll stay with the network my solver (sorta) found.

Code:

r5c5=5 ( r4c4=4 r4c6=9 ) r4c1=5 r6c2=8 r6c6<>8 r4c6=8 r5c5=9 => r5c5<>5
+--------------------------------------------------------------+
| 36 36 2 | 9 8 5 | 4 1 7 |
| 159 7 159 | 3 6 4 | 589 2 589 |
| 8 4 59 | 2 1 7 | 3569 36 569 |
|--------------------+--------------------+--------------------|
| 459 1 6 | 45 7 89 | 35 348 2 |
| 459 589 3 | 1 59 2 | 7 468 456 |
| 2 58 7 | 456 3 68 | 1 9 45 |
|--------------------+--------------------+--------------------|
| 169 2 189 | 7 4 69 | 689 5 3 |
| 3569 3569 4589 | 56 2 1 | 689 7 4689 |
| 7 569 459 | 8 59 3 | 2 46 1 |
+--------------------------------------------------------------+
# 66 eliminations remain

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Tue Oct 27, 2009 1:50 am Post subject:

Danny, here is a better view of it. its just a net starting with r4c1 (9)r4c1 - (9=8)r4c6 * \|\| (5)r4c1 - (5=8)r6c2 * \|\| (4)r4c1 - (4=5)r4c4 - (5=6)r8c4 - (6)r7c6 = (6)r6c6 * * all prove r6c6 is not 8

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Oct 27, 2009 10:48 am Post subject:

storm_norm wrote:

Danny,
here is a better view of it.
its just a net starting with r4c1

(9)r4c1 - (9=8)r4c6 *
||
(5)r4c1 - (5=8)r6c2 *
||
(4)r4c1 - (4=5)r4c4 - (5=6)r8c4 - (6)r7c6 = (6)r6c6 Twisted Evil

*

* all prove r6c6 is not 8

Hello Norm,

Yes, that's basically the reverse of the 2-stream forcing chain that I derived for that elimination.

Code:

r6c2=5 r4c1<>5
/ \
r6c6=8 r4c6=9 (r4c1<>9) r5c5=5 r4c4=4 r4c1<>4 => r4c1<>4|5|9 => r6c6<>8

One of these days I'll get comfortable with the (||) usage. I think it'd do a better job of listing my network.

Regards, Danny

Last edited by daj95376 on Tue Oct 27, 2009 10:49 am; edited 1 time in total

ttt

Joined: 06 Dec 2008
Posts: 42
Location: vietnam

Posted: Tue Oct 27, 2009 10:49 am Post subject:

storm_norm wrote:

found a one stepper for the playr.extreme.

Code:

its a net
but it can be viewed as a finned xy-wing
[(8=9)r4c6 - fin(9=5)r4c1 - (5=8)r6c2] = (4)r4c1 - (4=5)r4c4 - (5=6)r8c4 - (6)r7c6 = (6)r4c6; r4c6 <> 8

Nice find, Norm!
IMO, that is Almost XY-wing. Either [XY-wing: (89)r4c6, (95)r4c1, (58)r6c2] or (4)r4c1 must be true => r6c6<>8

ttt

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Oct 27, 2009 10:54 am Post subject:

ttt wrote:

IMO, that is Almost XY-wing. Either [XY-wing: (89)r4c6, (95)r4c1, (58)r6c2] or (4)r4c1 must be true => r6c6<>8

Thanks ttt!!! Idea

Code:

XY-wing: [(89)r4c6, (95)r4c1, (58)r6c2] => r6c6<>8
||
( 4)r4c1 - (4=5)r4c4 - (5=9)r5c5 - (9=8)r4c6 => r6c6<>8

Note: (4-9)r4c1 = (9-8)r4c6 = (8)r6c6 would throw a monkey-wrench into the solution.

===== ===== ===== ===== ===== ===== ===== ===== ===== ===== ===== ===== =====

This leads me to the network I wanted to present for Vanhegan/playr Extreme:

Code:

XYZ-Wing: [ (76)r1c9, (679)r1c7, (97)r4c7 ] => r3c7<>7
||
( 9)r1c9 - r2c8 = r6c8 - (9=7)r4c7 => r3c7<>7
+--------------------------------------------------------------+
| 79 8 1 | 3 4 5 | 679 2 679 |
| 5 4 6 | 7 289 29 | 389 39 1 |
| 2 3 79 | 1 89 6 | 89-7 5 4 |
|--------------------+--------------------+--------------------|
| 789 6 5 | 2 3 1 | 79 4 789 |
| 4 1 3789 | 58 59 79 | 3579 6 2 |
| 3789 2 3789 | 458 6 479 | 1 39 5789 |
|--------------------+--------------------+--------------------|
| 1 7 4 | 56 25 3 | 2569 8 569 |
| 6 5 2 | 9 7 8 | 4 1 3 |
| 38 9 38 | 456 1 24 | 256 7 56 |
+--------------------------------------------------------------+
# 58 eliminations remain

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Tue Oct 27, 2009 4:43 pm Post subject:

Danny, so what you have is an almost xyz-wing. or a finned xyz-wing.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Tue Oct 27, 2009 5:32 pm Post subject:

storm_norm wrote:

Danny,
so what you have is an almost xyz-wing. or a finned xyz-wing.

Norm: Let's split the difference and call it an almost finned XYZ-Wing. Very Happy

But, seriously, this does lead to a number of interesting possibilities. The foremost (in my mind) being:

* If an elimination created by one step exposes an advanced subsequent step, then it may be possible to back up to the position of the first step and search for an almost finned on the second step.

This is what I did to reduce my 2-step solution to a 1-step solution. I just didn't know that I was creating an almost finned scenario ... until now.

Regards, Danny

storm_norm

Joined: 18 Oct 2007
Posts: 1741

Posted: Tue Oct 27, 2009 9:24 pm Post subject:

Quote:

* If an elimination created by one step exposes an advanced subsequent step, then it may be possible to back up to the position of the first step and search for an almost finned on the second step

I am going to do this with your puzzle NR_76

http://www.dailysudoku.co.uk/sudoku/forums/viewtopic.php?t=3983

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