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Clement · Posted: Wed Apr 28, 2010 11:17 pm Post subject: April 29 VH

W-Wing 23 with strong link 2 in row 3 removes 3 in r4c7 solving the puzzle.

prakash · Joined: 02 Jan 2008 Posts: 67 Location: New Jersey, USA

A XY wing (169) pivot r4c6 followed by another XY wing (127) pivot r5c8 clears it up.

Marty R. · Posted: Thu Apr 29, 2010 3:49 am Post subject:

Also a Skyscraper on 2 in columns 39.

peterj · Joined: 26 Mar 2010 Posts: 974 Location: London, UK

Also one of I suspect many xy-chains that solve it..

(2=7)r5c3-(7=2)r2c3-(2=3)r2c9-(3=1)r7c9-(1=2)r4c9; r4c1<>2, r5c7<>2

But probably in sledgehammer territory already..

roaa · Joined: 18 Apr 2009 Posts: 112 Location: Sweden

The xy-wing 127 in rows 4 & 5 solves it in one step.

arkietech · Posted: Thu Apr 29, 2010 1:07 pm Post subject:

I found four different one step solutions:
2 skyscraper 2's
xy-wing 127
turbot taking out a 2 in r5c7

tlanglet · Posted: Thu Apr 29, 2010 4:03 pm Post subject:

I found a xy-wing 2-34 with vertex 24 in r3c1 and pseudocell pincer 34 in r35c7; r4c7<>3
This step is simply another view of the w=wing 23 already posted.

Ted

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

Same skyscraper as Marty. Unquestionably the simplest and most efficient solution. Quite frankly I dismiss other solutions as rather tiresome and irrelevant. Evil or Very Mad

Wendy W · Joined: 04 Feb 2008 Posts: 144

I don't quite see it like that: It just depends which "tool" you happen to see first. For me it was XY-567, then the much-mentioned XY-127. Does one start at the top or the bottom? It's arbitrary.

cgordon · Joined: 04 May 2007 Posts: 769 Location: ontario, canada

Mogulmeister · Joined: 03 May 2007 Posts: 1151

Well, as has been discussed elsewhere on this board many times, different things are spotted by people depending on their proclivities.

tlanglet · Posted: Sun May 02, 2010 1:13 am Post subject:

If you are judging "simplest solution", I would first suggest a definition of the term.

For example, it was declared that a skyscraper was the best. But look at the lowly turbot offered by arkietech. Comparing with the skyscraper we note that:
both are single digit patterns; in this case the same digit, 2
both steps involve four bivalue cells; two of which in this case are identical
both make a single identical deletion, but the skyscraper makes a additional unnecessary deletion (negative value for the skyscraper)
the skyscraper requires four boxes; the turbot only three boxes (more negative for the skyscraper)

Thus based on this set of four criterion, the turbot used less resources that the skyscraper and would therefore be declared the winner. Razz

Ted

Mogulmeister · Joined: 03 May 2007 Posts: 1151

I can see cg saying that he finds skyscrapers easier to spot. Wink