Sudoku Puzzles

Thanks guys, for the info. I haven't yet had a chance to do more than glance through it, but I saw that it's there. I'll study and ponder as I do the puzzle later this morning.

why is there such a huge difference between hard and tough?

First?

It's like going from a plane to 3D thinking (FCs to various depths) so it is effectively possibly squaring the level of difficulty. I can only dive in the shallows.

7.01

4.37 not too bad today

Easy till 28 filled.
Then, whether e7 = 5 or 6:
a8=1, c3=1, h6=5, c9=3 and h1=1
Simple filling till 81

See you tomorrow

No 1, I am floundering in the shallows with you. These toughs make me feel really thick whereas the hards are a doddle.

7:48

Good Maen

16:06

14:14 and a challenge for me today. Congrats to those with the great times. Now to work. Have a wonderful Maen, everyone.

a giraffe.peeping in to something or peeping out of a fence??
well i spent only a couple of mts[may be around 8 to ten] to see it.didnt time myself today.

11:45

Puzzle was worth the giraffe! :o)

i spent 15.10 getting to 28 filled, and tried the rest, but alas, it eludes me...i see how burck from spongecake gets e7 = 5 or 6, but a8=1 escapes me...i have a8 as 1,8, c8 is 1,5,7,8 and a1 is 1,2,8, so where's the elimination? same types of thing for c3, i have c3 = 1,2,7,8; i have h6 as 3,5,9; c9 as 2,3,5,7 and h1 as 1,3,5,7...i know i'm missing something
any ideas out there???

19:32 - love the giraffe! I messed up on possibilities and caused myself to have to guess. It went fast after that!

See you all tomorrow and I'll give a puppy update - whether you're interested or not!!

Naomi, there is an X-wing in the 2's that allows you to eliminate c9=2... but it doesn't help much. Also, I only see easy to 27 filled: a2=2, d4=2, d7=1, f6=1; so I suspect there is another mistake somewhere.

ok bill...thanks but i have really waiting to ask this one...what is an x-wing or a y-wing, i keep hearing about them but even with the 'hint' i cannot eliminate...can you educate me? many thanks

Beautiful giraffe! Brings back childhood memories of the 'Friendly Giant' on tv.

Ah yes, finally see that a5=6. X-wing is the 2's in a1/a9, i1/i9. Prohibits any other cells in rows 1/9 to contain 2.

hi bill -:)i have the a5=6 already, and can now see the x-wing in the 2's and am working on the eliminations...also FYI a2=4 not 2 as you had suggested but the other cells are correct

Hi Naomi. Scroll down this page - click on proofs, then click Bruno's Proofs and under forbidding chains for beginners, all will be revealed. Good luck!

Naomi: typo! sorry...

If a9=2, g7=2 and a8=1; or, if a9=3, a1=2 and a8=1. Therefore a8=1. Maybe that will lead somewhere...

51:34

Are you guys solving the same puzzle I am? I see stopping points at 26, 30, or 31 filled (depending on how observant you are), but filling in the 27th number uniquely determines 29 through 30, so you *cannot* say 'UP to 28'. Oh, and a9=2 is a unique placement, why are you even bothering with x-wings on it?

hey ugly people

Marti: I guess we're not solving the same puzzle! lol
I think you've made a mistake somewhere. I'm quite certain that the puzzle is easily fillable to 28 and tough after that. You can probably find your mistake by comparing what you have filled at 26. The only easy fillings are: a2=4, a5=6, More...

12:35

Would someone please explain the shorthand? i.e. a9=2. And for those of you who solve so quickly - how do you do that? Is there somewhere you learned some of the tricks from?

Took a while! 8:22 totla minutes, 4:02 to set up, and 4:20 to solve. This was harder than usual.

Good mAen to all.

What does it mean 'filled to 28'

A very ugly solution:
1) Start at 23 filled. Unique Possibilities to 27.
2) Locked 8's forbid 8 at ACGI 5. UP to 28.
3) X wing 2's forbids 2 at BC9, BG1.
4) Colors 7's: e3==e4--df5==g5 forbids g3.
5) Locked 9's forbid df5=9. Colors 9's f8==g8--g5==c5--c2==d2 forbids f1,d9
6) a4=8 == a4=3 -- a9=3 == a9=2 -- i9=2 == g7=2 -- g7=8 == bc7=8 forbids a8=8. UP to 31.

7) X wing on 7's forbids 7 at g4, bdf3.
8) Pair 28 forbids b1=8.
9) colors 7's: b1 ==b9 -- c8==f8 forbids f1=7.
10) c2=7 == c2=9 -- c5=9 == g5=9 -- g8=9 == f8=9 -- f8=7 == c8=7 forbids
c9=7, c46=9, g46=9, f8=5
11) h9=9 == g8=9 -- f8=9 ==f8=7 -- c8=7 == b9=7 -- b9=6 == d9=6 -- e7=6 == More...

13) c9=5 == c9=3 -- AI9=3 == a9=2 -- i9=23 == i9=45 -- h7=4 == h7=3 -- h6=3 == h6=5 forbids h9=5
14) locked 5's forbid g456,i56=5. UP to 33.
15) pair 38 forbids b4=8, h4=3. pair 59 forbids 59 at bc6. Up 35.
16) pair 28 forbids 28 at b7. Pair 56 forbids 5 at cf7. UP to 81.

Total sets: 46. Maximum depth 6 at step 12.

Hey Steve - Where can a person get the secret decoder ring to understand what all that means?

Burck

I tried to follow your logic. If e7 = 5 it took me a lot of steps to show your values. If e7 = 6, I could also get your values with a lot of steps, but I also had a contradiction by that point, so for me, it was easier to eliminate e7 = 6, then relatively easy (just eliminations) to 81. There must be an easier possibility to eliminate.

Hey Marti, I'm with you, I didn't stop at 27 either. Got stuck on 50something for a while tho !
Concentrating hard on Steve's solution, but not understanding most of it still.

Steve,
On step 10, how do you forbid c46=9, g46=9, f8=5 ?