Sudoku Puzzles

Same as the last two days up to minor changings!

easy fillings to 51 filled, looking at g8, eliminate g2=3, then easy to 53 filled, then looking at 2 in Bb2 eliminate e6=2, then easy to end.

yesterday was :easy fillings to 51 filled, looking at c1, eliminate c9=4, then easy to 53 More...

easy to end.

These still take me too long.

hi with gb's solutions off to the puzzle

Complete solution (usual disclaimers about typos):

Part 1

1. a1 & c1 must = 1 or 5; make necessary eliminations in 3x3 & row-1
2. g9 & i9 must = 2 or 7; make necessary eliminations in 3x3 & row-9
3. Due to step 2, in column-h, 8 must be in h7 or h9; eliminate from other cells More...

Part 2

5. a9 & b9 must = 3 or 6; eliminate from other cells in 3x3 & row-9
6. Simple elimination: b8=4, c8=1, c7=7, a7=2, c1=5, a1=1, h7=1, h9=8
7. 3, 8 & 9 must be in d7, e7 or f7; eliminate from other cells in 3x3
8. Simple elimination: f9=4, d9=5, e8=6
9. In row-5, a5 & h5 More...

Part 3

11. In row-1, 6 must be d1 or f1; eliminate from other cells in row
12. Simple elimination: h2=6, h5=5, a5=6, a9=3, b9=6, a2=4, b5=7
13. f3 & f5 must = 1 or 8; eliminate from other cells in column-f
14. In row-3, 1, 4 & 8 must be in d3, e3 & f3; eliminate from other cells in row & 3x3
15. g3 & g8 must = 3 or 5; eliminate from other cells in column-g

Part 4

16. Simple elimination: b2=3 (3 has been eliminated from all other cells in row), b3=9, d1=4, g6=1, d5=1, f5=8, i5=2, i9=7, g9=2, f3=1, e3=8, e7=9, f7=3, d7=8, e6=5, a6=9, a4=5, f6=6... easy eliminations to finish

whats that little birdie up to?

23:02 slow

21:05 I obviously need more caffeine in order to think

oh dear, too many beers to be doin this

Always enjoy this picture. Slow time, but all logic and no guesses or 'hints'.
Why is it that children never want to SLEEP at a sleepover?!!!!!!!

4:42

gb, I have learned much from you and would likely not have become addicted without your logical approach and support.

Same situation as yesterday. Today it was:
35 359
35 35
So must be a 9, otherwise multiple solution puzzle. Do you consider this fc, trick or simple elimination?

To Ron from Texas

Like you I arrived at the position
35 359
35 35

Strictly speaking you can't assume the puzzle has only one soln (even though we 'know' the 9 is correct. I ignored the 9 : still got there in the end.

Hi Ron,
I do not accept the argument 'otherwise multiple solution'. Reason : I chose for gaming rule 'find all solutions of a given puzzle'. So it's the prover's work to establish unicity, he must not rely on the information that the puzzle has unique solution.

I actually timed myself today. 21:04. No guessing or hints!

Now you guys are confusing me. I don't usually post, but are you saying that it is valid for a sudoku puzzle to have multiple solutions? I thought 1 of the premises was that there was 1 unique answer.

13.17 Don't know if I'm getting better or these are getting easier (the latter, I think!)

I'm a little surprised at the elimination issue Ron and JRD encountered, as I didn't have an issue with any of the eliminations I made. I'm now wondering if I made a mistake when marking my eliminations but was lucky and it allowed to solve without any problems.

Hi Mike from Illinois,
it's usual that sudokus have only one (btw all problems here have been shown having unique solution), the same way as it's usual that the initial grids show some symmetries.
I was just saying that we can decide : either to prove that the solution is unique, or to find More...

TM (or anyone else), I am having trouble at the e6=5 elimination. I am right there with you before that, but cannot seem to get that elimination. Also, the d4=1 I am assmuming is a typo for d3. I also had to use the 35, 35, 35, 359 to solve, because I was unable to eliminate the 2 as a possibility at e6. Any help would be great. Thank you!!!

TM,

I was just typing up the same comment as Mike from Iowa City.

Two days ago I had the same issue, I solved it wihtout any fc's. Then, when I went back to prove it, I couldn't do it. I had accidentally cleared a number that could be done logically.

TM, got the same process as you do (typo d1=6 (d4=3))and didn't have the issue 35 35 35 359. Got 35/359/359 and then 35/359/35) but 3's and 5's find their place.

over one and a half hours 'TOUGH'

Hi Mike from Iowa City.
You eliminate the 2 at e6 because whatever you choose in b6 (2 or 8) you get 5 in e6. It is a bigger chain.

I would have the same issue in not being able to determine d1=6 if that was the typo. I am unable to eliminate the 2 in d1 either. Just wondering what I am missing.

Thank you Valy. I knew I was missing something. I really appreciate your help!!

can't even follow your language, let alone the logic! i can get most of the hards, but end up printing out the toughs to spend more time on when i'm not busy. happy holidays to all

Yes, the d1=4 is a typo, it should be d3=4, and after going though my solution again from the beginning, I get hung up on the e6=5 too. It was probably a lucky dumb mistake where I somehow left the 2 out when filling in the possibilities.

Will ammend my solution.

Indeed, gb, this one is halting again at 53 filled!
What would be wrong in their sudoku-generator? Do you think it has a hiccup??
Anyway, to solve it to the end, I do the following:
- take any one of a double value
- try to solve it from there
- two possibilities:
- a I get More...

...should have a unique solution, afaik!

I didn't use the timer, because I can never complete the tough without guessing. Until tonight! And I didn't use the timer! I think I did it in about 15 mins.

15.32

27:02. Uuuggghhh. I got wicked stuck. See you all tomorrow. Wish the picture was one that I hand't already seen.

and fc means .....

please????

someone help

nobody cares what it means at home !!!!!

I'm sure I said this yesterday....look in proofs, top right, go to Bruno Greco's solutions (he's our gb) fc = forbidding chains, all explained in gb's sandbox and I'm not saying it again! :))

Wowie - Under ten minutes, I am so excited!

I did a little research, found about fifteen different handheld soduko games, ranging from $15 to $35 (don't know the conversion to other currencies, sorry). None said it would allow possibilities and would delete them when a correct number was More...