dailysudoku.com

jLo · Joined: 30 Apr 2007 Posts: 55

TexCat wrote

Mogulmeister · Joined: 03 May 2007 Posts: 1151

I don't see a skyscraper on 1's but perhaps cg meant x-wing on 1's which I see you've already applied j-Lo. (Although that doesn't remove the 1 in r2c5)

Have a look at row 8 and you'll see that there is a hidden pair. This will create a single on row 3 which in turn will remove the 2 in r2c3. You can now build that xy wing.

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

I always thought skyscrapers could be horizontal as well as vertical - they are if you rotate the page! Maybe vertical skyscrapers are y wings and horizontal ones are x wings. Anyway, using George's grid on his first post, there are two 1's in col. 2 and two in col 8. By my reckoning since the two 1's in Row 2 line up. one of these has to be a 1. Therefore the 1 in R2C5 is eliminated. No???

Mogulmeister · Joined: 03 May 2007 Posts: 1151

cg,

Yes skyscaper can be vertical or horizontal. However they are strong links of different length that both have a node on the same row/column.

I see where you're driving at but your row 2 has actually got 3 boxes with 1 in it so it is not a strong link. The other problem is that for a candidate to be eliminated it must be able to be "seen" by the two ends of the skyscraper.

cg - if you want to see a graphic example of a skyscraper look at the one that is illustrated in Mesmin's puzzle in this thread
[url]
http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=1860&sid=9cb62644c9357068f48772c4a472f413 [/url]

The skyscraper is in pink, the eliminated 5's in orange.

csc · Joined: 03 May 2007 Posts: 14

I've just completed this puzzle, after having read the discussion on it. I was at the same position as George, when I got stumped. Seems to me that the most straightforward route is as suggested by Steve R. After having identified the 13 hidden pair, and getting the 7 in r3c5, you need only 1 xy wing (to eliminate 8), to complete. Thanks Steve.