dailysudoku.com

[nataraj]

not very hard, when UR looking at it the right way.

[Mindwarp]

A fairly easy puzzle. On Draw/Play, first enter all numbers possible without sweep and after that just sweep and eliminate.

[TexCat]

I got stuck here:

[sdq_pete]

The UR on 27 putting 3 at R3C5, presumably. Since we normally don't seem to have to rely on UR's I'm curious if anyone spotted an XY wing or such.

Peter

[duffy]

Since I learned about UR's (thanks, Keith!) a couple of months ago, I find them interesting and useful. After the previous one for 27's in boxes 2 and 8, there is immediately another one in boxes 1 and 2 on 26's. And for the record, I did not see any wings except for an earlier x-wing on 5's in rows 2 and 4.
I am glad to be back here, after having to re-register since the server problems a few months ago.

Don D.

[cgordon]

[lkmckin]

You can use a finned fish on [2] in cols 1 and 7 to eliminate [2] from r2c2.

You can use an XY wing to eliminate [5] from r2c1.

Now, r2c7 is forced to [5] and the rest comes easily after that.

I hate URs because they assume something additional about the puzzle (that it has a unique solution).

[nataraj]

sure thing, peter.

from this position

[Marty R.]

[sdq_pete]

[cgordon]

I'm going bonkers with this one. According to Texcats grid (and my solution) there is a UR for 257 on R2C17 and R4C17. That should make R2C1 a 7 and eliminate the 7 from R7C1 - but it doesn't - R7C1 is the 7.

Pls help!!

[Marty R.]

[cgordon]

Marty.

I didn't know that!! A week ago I thought I was an expert on URs. I was gonna move on to Medusa Wraps. Then on Monday I found out you can't use 3 triples and a quad in a UR - and now the corners have to be in 2 boxes. I should stick to naked-singles.

[TKiel]

I'd clear that with the significant other first.

[TKiel]

When I got here (a spot similar to Texcat's and nataraj's position) I saw but decided to ignore the <27> UR in hopes of finding something else, so I went hunting for wings. I missed the (25)(23)(35) with pivot in r1c1 but noticed there was a (23)(35)(25) with pivot in r3c3. Unfortunately, no exclusions were directly possible with it. But applying W-wing with coloring logic (I hope) to the XY-wing, the strong links on <2> show that <2> can be excluded from r1c2.

[Asellus]

Tracy,

Your coloring based on the XY Wing is more interesting than you realize.

[keith]

The UR solves it.

Or, there is an XY-wing followed by an X-wing and then a remote pair.

Keith

[cgordon]

I'm into ERs (an advanced technique). There's one on 5's from C7 that says R4C3 cannot be a 5. This exposes the UR already alluded to.

[Mogulmeister]

Empty rectangles (ER) is a technique that (in my opinion) helps out at the early phase of a puzzle and is a nice visual tool. Havard put it forward

http://www.sudoku.com/boards/viewtopic.php?t=3251&start=0

and on his own board.

I find these days that I don't encounter them nearly as much and can only conclude that it is because I am making those eliminations with other strong-link based techniques.

[TKiel]