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Difficulty: Medium Thursday, June 14, 2007

Not Completed Play This Puzzle

CHAT LOG for Thursday, June 14, 2007

12:13 am
itzie

Done. I think it was all or mostly cross-hatch.
12:13 am
itzie

no greens!
12:31 am
tresbizzare

easy
1:18 am
lawfully

Not bad... can't understand why I couldn't hit the first time though
2:32 am
h

21 filled and ive hit a wall. sigh.
2:33 am
h

doh.
2:34 am
h

ok make that 22 filled...
2:37 am
h

ok - its all about pointing-pairs...
5:20 am
spreadeagle

23 filled. Going green.
5:23 am
spreadeagle

This looks so easy, but I'm still not seeing the solution.
5:29 am
spreadeagle

AHA, pointing-pairs it is.
5:31 am
spreadeagle

I hate it when I miss the obvious.
5:42 am
Phil

start
6:03 am
Phil

done
6:09 am
Andy

go
6:21 am
Andy

done
6:22 am
Andy

No greens. Not sure what pointing pairs are... maybe I used them? :)
6:32 am
smooth_pappa

go
6:37 am
smooth_pappa

done
6:37 am
smooth_pappa

no greens
7:25 am
peternl

hi all
8:39 am
UnikeTheHunter

Go.
8:44 am
hokie carla

yep, easy for a medium (I usually have the hardest time with them for some reason)
8:55 am
drwho

Difficulty score 20. The distinctive feature of the mediums here is the need for pointing pairs and/or box-line reduction (a.k.a. region intersection analysys, intersections or virtual cross-hatching).
9:14 am
UnikeTheHunter

Done, no greens. Two virtual crosshatches. Found a pair, but actually did the cell by missing digit.
9:57 am
spellacked

pretty easy for a medium
10:27 am
RodeoRogue

go
10:34 am
RodeoRogue

done. extremely easy for a medium. Usually these ones kick my butt.
10:34 am
brianarn

Ditto. It wasn't too bad. I seem to get stuck with advanced techniques and forget simpler things. :D
10:35 am
drwho

The medium puzzles here require at most 3 techniques: cross-hatching, missing digit scans and virtual cross-hatching.
10:36 am
drwho

It is the virtual cross-hatching technique that distinguishes a medium from an easy.
10:37 am
OrangeSlice

I do that on easy ones.
10:40 am
brianarn

I catch myself using unique rectangles on medium ones sometimes - I mean, other things wind up identifying the relationship, but they seem to pop for me nonw
10:40 am
brianarn

now*
10:42 am
OrangeSlice

I use any technique I see.
10:57 am
drwho

Sometimes the more advanced techniques are easier to see than the "simple" ones.
10:59 am
drwho

Brian, what do you mean by unique rectangles? I don't find them very often. I wonder if you are really referring to the X-wing technique?
11:02 am
brianarn

The definition I use of unique rectangles is that from the brainbashers.com sudoku help area - basically, a case where you see four squares on the grid that could be the corners of a proper rectangle
11:02 am
brianarn

and they'll all have a pair - say, 3,4 - but one of them will also have extra digits - like, say, a 9
11:03 am
brianarn

then you know that the one with the extra digit must be 9, because otherwise the puzzle could be ambiguous
11:03 am
drwho

Okay, that is the unique rectangle. I really don't use that technique at all.
11:03 am
brianarn

I don't necessarily go looking for it - they just tend to pop at me. :D
11:04 am
parsec

I never see XY-type things. I'm all over the unique rectangles too, though.
11:05 am
brianarn

on a rare occasion, I get an XY-wing, but that's not too common for me to be able to spot
11:09 am
drwho

I highly recommend learning the alternating inference chain method. It pulls together a bunch of seemingly unrelated techniques. The scanraid site has a link to a definition of AIC.
11:10 am
brianarn

What's the URL? I'm not familiar with the scanraid site, but I could use a new technique :D
11:12 am
parsec

Then there's the "I have no idea why, but I'm sure the 2 goes there" technique. Is there a name for that? =)
11:12 am
brianarn

I like to think it's good intuition? :D It only works for me about half of the time, though.
11:14 am
parsec

Half is pretty good for that one. =P
11:14 am
drwho

The scanraid site is:
http://www.scanraid.com/sudoku.htm

The AIC discussion:
http://www.sudoku.com/forums.html
?utm_source=301/viewtopic.php
11:14 am
brianarn

Thanks!
11:18 am
brianarn

25 puzzles until I've done 'em all - kinda weird to think about :D
11:19 am
drwho

Looks like the sudoku.com site changed things so the URL I gave you doesn't quite work. When you get there, find the Advanced Techniques link then look for Alternating Inference Chains.
11:24 am
drwho

Parsec - I think it is called an "educated guess", usually just referred to by its abbreviated name, "guess".
11:24 am
parsec

Nonsense, drwho! It's an extremely scientific and exacting technique! =P
11:24 am
drwho

No doubt, but you wanted the name.
11:25 am
parsec

True. Uh, thanks.
11:27 am
drwho

Remember, every wrong guess eliminates a candidate, so it is a valid technique of analysis. The purists will call it a brute force technique, but what do they know.
11:56 am
Limer

ha
11:56 am
Limer

Nailed that puppy
11:56 am
Limer

Rank me, baby
11:56 am
Limer

No green, or red
11:57 am
Limer

Cue theme muzak.
12:14 pm
drwho

To the dump, to the dump, to the dump dump dump...
12:14 pm
drwho

...said the Lone Ranger when Tonto asked where they were going.
12:19 pm
drwho

Okay Limer, the Lone Ranger stole it from William Tell, now I've stolen it from the Lone Ranger and given it to you.
12:20 pm
drwho

The Limer Overture.
1:59 pm
Krys10

heh - dr who - my dad used to sing that when we were headed to the dump - I thought maybe we were the only people who heard those lyrics in there
3:39 pm
helenkeller

go
3:47 pm
helenkeller

done
3:47 pm
helenkeller

no green
6:06 pm
brittlefish.com

go
6:15 pm
Zugzug7

go
6:18 pm
brittlefish.com

done, no greens.
6:20 pm
Zugzug7

done
6:28 pm
jawilke

go
6:34 pm
jawilke

done
6:36 pm
hurshy

with a MEDIUM??? that's fast. mediums are the hardest ones!
6:43 pm
hurshy

ok, i'm done too.
10:02 pm
herinfernallady

done
10:02 pm
herinfernallady

go