dailysudoku.com

wapati · Posted: Fri Aug 22, 2008 4:27 am Post subject:

I see two finned x-wings and a 4 cell xy-chain.

That is hard enough. Thnx.

Asellus · Posted: Fri Aug 22, 2008 4:38 am Post subject:

For me, it was a one-step solution.

ravel · Joined: 21 Apr 2006 Posts: 536

There is a useful useless w-wing.

tlanglet · Posted: Fri Aug 22, 2008 1:23 pm Post subject:

I also found the useful useless w-wing.

Ted

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

It did me in! I think I found the two finned x-wings - if they are indeed at R67 to get rid of 4 in R4C7 and at R58 to get rid of 8 in R9C8. But I'm stuck after that.

Earl · Joined: 30 May 2007 Posts: 677 Location: Victoria, KS

Asellus,

"For me, a one step solution."
You have a doubting Thomas here.

Earl

storm_norm · Joined: 18 Oct 2007 Posts: 1741

one step solution extending the pincers {4} from the W-wing.

(4)r8c2=(4)r7c1-(4=6)r7c7-(6)r4c7=(6)r4c4-(6=4)r5c4; r5c2 <> 4

Asellus · Posted: Sat Aug 23, 2008 5:49 am Post subject:

ravel · Joined: 21 Apr 2006 Posts: 536

4-cell xy-chains are also called "generalized xy-wings". For me an own name is justified by the fact, that i look for them sytematically like for xy-wings, while i find longer xy-chains more or less accidentally.
I go through the units. Whenever there is a pair of bivalue cells with a common digit (here the 6 in column 8), i look, if both other digits (8 and 3) force the same number x by seeing a bivalue cell 8x and 3x resp.
This is done very quickly (faster than an xy-wing search), because normally there are only a few potential "pivot pairs".

storm_norm · Joined: 18 Oct 2007 Posts: 1741

Ravel,

are you ending your posting career on this site at 999 posts??