Done

hi all

Hey, Moedog

woo hoo!

nice and easy

Done

nice change from a couple of experts. Thanx, Dr. Who.

hi all

come to visit my msn space http://orsetta87na.spaces.live.com/

I'm waiting for all you and if you want you can write me a comment if you like it

yeah a nice quickie...have a good day all

I think people will make comments if they wish too

hi all

go!

done

go

done

Difficulty score 14. Maybe I'm not alert this morning, but that seemed harder than yesterday's expert.

And yesterday's was very easy except for a couple of short XY chains. Don't bother learning the XY-wing strategy, learn the XY-chain technique and you will never need an XY-wing.

what's the XY chain technique?

Its explained on http://www.scanraid.com/sudoku

thanks, will look that up

hm, seems I am not allowed to see that page?

Oops... http://www.scanraid.com/sudoku.htm

thanks :)

I always solve sudokus without really knowing any techniques, but there have been a few puzzles lately that I had trouble with. This might be the missing link.

XY-wings and chains are rather prevalent in expert puzzles if you've a mind to look for them.

will study them, now I want to know :)

"cells that can see both of them" ?? I have no idea what they mean in the explanation, lol.

go

wow, I actually got stuck for a few minutes on today's easy. I used a unique rectangle and an aligned triple to free myself though, lol

OrangeSlice, do you know what they mean with that phrase of cells that can 'see' other cells?

Hard to explain it further than that

Think about how each cell relates to every other cell in terms of what a value within that cell can change somewhere over across the board.

done.

For example, if you isolate a '5' in some arbitrary cell, any other cells within that row, column and box can't be a '5' anymore. That's because those cells can be seen by the '5'

to "see" a cell, means imagine that you are standing inside that cell - then you can look horiz, vert, and to your fellow-clock-mates only...

block-mates.

so it can be said of cells in the same row, same column, but also for example in the same block?

ah, thanks, that clarifies things :)

yup

Then we extend the concept to multiple cells. We look for cells that can be seen by two or more cells when we're doing more advanced techniques.

ah, of course. Thanks again, both of you. I think I can work it out now :)

yw - btw, i needed a unique rectangle 345 also, but nothing more advanced than that.

hmm, well the rectangle made a naked triple in the lower-left box, which I used to isolate one cell (leaving a naked pair) and solved from there.

Granted, that's not more advanced, but I usually expect to just cross-hatch and xwing my way through easies.

Go

I can't tell you the named techniques I use -- I'm self taught (well, my wife and I developed our techniques separately then traded). I crosshatch the blank table to find where items MUST go, then after each pass of 1-9 I look for "low hanging fruit" where there are only two or three squares left in a row, col or box, and find which ones can only go in one spot, or which pair in one box forces the third one in a neighboring box in the same row, for instance. This one only took two passes like that.

Done. messed up once. Boo

Hi PEEP! Hi Sprite!!

hey, a unique rectangle! my favorite!

This is a hard easy one, not a lot of set ups

hey Krys!

this one was easy

but I think I might benefit from knowing those XY chains for some more expert puzzles. Or at least I hope I will :)

done

Done, no greens. It was good to see the uniqueness problem rectangle.

Woohoo - I'm in the rankings area now! Nifty.

Go

I always feel bad when I lean on greens in an easy - doing my best not to, but slowing down. Arg.

Done

Fell back on greens as well. Ah well, it IS monday, after all :)

I think I should stop looking at the difficulty, because it seems that I stumble on the easy ones since I get sloppy thinking "It's easy"

And I don't know what the method of determination is... but I find that drwho ranks them differently

I believe drwho uses a program to analyze difficulty, which I think is neat. I like those ratings to compare with the description provided by the site. :D

Probably something in the TARDIS.

I had a pseudo-checkpoint, where I just copied to notepad what the cells were, and I'm glad I did because I'd have had to restart, but it's going smoothly after a mini-reset. I should just pay the $15 already. :D

Be a pod person. Join us.

Woohoo - I think that's the first puzzle I've solved here without greens. :D

gratz!

I heard people talking about the uniqueness rectangle or something - I tried to use it and failed and that was my one mistake. :D Otherwise just kinda banged through it.

and in re-reading the description of unique rectangle, I realize I applied it backwards creating a deadly pattern. That explains why I got stuck that way. :D

Done! Easy! No guesses but used greenies.

hi!

i'm brazilian sudoku's player

Thanks to brianarn for the kind words about my difficulty score. For anyone who is curious I have put up a website and have more explanation, and source code too:
http://pauls-pc-repair.com/sudoku

Welcome wowelster!

done! the first 4 me : )

wtg himuran

go

done

I just read your code drwho -- it's been awhile since I've poked through some C. That was quite a fun read. It gets me thinking about putting a non-curses GUI on it, and/or maybe a web front to it :D

go

done