Sudoku Puzzles

19/28 type, see also
12-sept, 26-sept, 27-sept, 29-sept, 02-oct, 08-oct.

14:42 with automatic poss on and allow incorrect moves on wheres Billy???

gb I've found 10 numbers before I've had to pause and take stock. Top row - bottom row except for 3 and 7. The 9 in 2nd column and the 1 in 9th column.

and B B BOTHER I've just lost all my numbers by submitting a comment.

Replotted my numbers.(It took longer the second time) After that first 10 I had to guess and guess again.

fi - unlucky. As far as I can tell the 1 in the 9th column could be in row 4 or 6. How do you know which one?

How did you find the 1 in the 9th column?

6:31
Who submitted this pic? Where?
Lovely

where's the pic from? Doesn't ring a bell
Didn't time myself, just took it slow, although I had to guess in three spots.

definitely not Texas - Spain?

35:16

I've found 9 and I've now run out of all my logic (which isnt difficult for me) but I am NOT giving up and guessing.......see you all sometime in 2006 at this rate...

Good grief! I love the 'tough' group. Deb, you had me lol! Anyways, I got stuck and saved the puzzle to Excel - a trick gb taught me (Thanks!), so I'll work on it tomorrow or next week or 2006 or whenever. The picture is very intriguing. My first guess would be the Mediterranean - Italy, More...

27:48. Must have been that extra portion of turkey. anyway that's my story and I'am sticking to it

did it again! this is big. 2 days in a row that I actually finished it on my own. i did use all the aids and needed them i have to admit as i tend to make mistakes that lead me up the garden path. i'll learn not to i guess but i seem to be in a hurry all the time even when i don't time myself. i tried to use the timer but messed up by forgetting to unpause. took about 30 mins with one guess.

38:30

How do you save the puzzle to Excel? I right clicked on the grid and selected 'Export to Excel', but nothing happened...

Pretty tough puzzle, I don't think I can complete this without taking a guess...

looks like the Mostar bridge, or where it was until they blew it up, but I think they rebuilt it

Not bad, thanks GB and good knowledge jock. I'm glad to see my pic got in. It is the Mostar bridge after they blew it up during the Bosnian war and yes it has been rebuilt.

it was logic by 75% before got stuck!! so sad :(. did not want to guess

18.08 Probably about average for the tough, though it's difficult to keep track of time with minor interruptions. Not bad for an ageing granny anyway, but nal how did you do it in 6.31?

6.31? Hummm I started the time after I put in the possibilities and still took me 8 min. Perhaps that is not an honest 6.31???

Still no further forward...JH - Good grief indeed!! I takes me an average of 4 mins to put in all the possibilities and check em - so that would leave me 2.31 to do it as fast as nal. It aint ever gonna happen!

Blair: In order to copy into Excel, I click just outside the top left corner of the grid and drag to the lower right, highlighting the entire grid. I then press ctrl + c to copy, open up Excel, and press ctrl + v to paste. It's great because then one can format and edit the cells along with the More...

Hi world, This one is equivalent to 05/09/12. Proof :
1) Take 05/09/12 grid, exchange rows and columns : R1(bottom!)<-->Ca(left!), etc.
2) Now move rows 123456789 (1=bottom!) on new positions 789654123
3) Now move columns abcdefghi(a=left!) on new positions bcadefigh.
4) All More...

continued (must learn conciseness...)
Now applying the same 'dictionary' (rotating, changing rows, columns, values) to proof of 09/24 you will mechanically get a proof of today's. Try it ! Or see the method explained step by step on 10/08 example.

16.37 with the auto remove on but no guesses unlike the hard & medium today. I have a pic of Mt Rushmore and thought all you northeners were having fun saying you didn't know what it was

10:54 I don't know what all this 'proofs' stuff is, but it sounds no better than using the available aids. Use your own brain, people! Otherwise you might as well be letting someone else do it for you, and where's the point in that?

You're right Frank. However,
1)looking at someone else's proof may help learning tips to improve your own efficiency.
2) Remember 'solving a puzzle' is in fact : 'finding all solutions'. So, making a guess that leads to ONE solution doesn't prove that it's the ONLY solution. ''Proofs' stuff' as you say, is a way to make sure that there's only one solution.

For anyone who cares (please Frank don't read this) here is a proof of today's automatically derived from 09/12's :
1) Easy eliminations lead to 28 cells filled.
(For easy following of explanations below, complete first the online board with
remaining possibilities in each empty More...

continued:
Perform the same with the only choices : 37 in g1 and h1, then 16 in h2 and h3, then 23 in b5 and h5.
3) Look at 5 in Be2. Whether it is in Cd (in which case d5=8%cell), or it is in e2 (in which case h2=1%cell) : g5=6%cell. Follow now easy eliminations up to 41
filled More...

continued :
5) Now look at b5. Whether b5=2 (in which case g6=2%block, g7=5%cell), or b5=3 (in which case a4=5%cell,c8=5%col) : g8=7%cell. Now easy eliminations lead to unique solution.

I understand proofs to be a mathemtician's tool, but this has absolutely nothing to do with math. What would you or anyone else do if the numbers were replaced with, for example, nine different colours? Or the letters A-I? Or any other nine distinct symbols (as long as there was an established heirarchy)?

Andre - I don't do 'Tough' much because i start to cheat and I beat myself up over it! Sad isn't it?!

i know what you mean Billy i have to use all aids as brain cells are not replenishing! Apparently we are supposed to excercise everyday for 20 mins as well to improve brain power!!

Frank : I don't understand you. Of course the numbers in our game aren't but symbols, but what would it change if they were letters : reasonings like : 'A is somewhere in this block so can no more be in that row' stand exactly the same, don't you think? There's no math at all in proofs, only logic.

8:54, two guesses and very lucky that they were correct ones. First time this has happened to me. Must be my lucky day.

Have, to date, both used aids and resisted the impulse to consult gb's (de France) formula (no offence gb). Determined that this could be solved applying logic (certainty factor), law of probability, and process of elimination using basic algebraic grid (ie x,y axes) x = 1-9 columns y = 1-9 rows More...

Apologies Jimmy,Alex, gb et al, Had to sleep, work, socialise etc before I could get back to check out how I got my 1 in the 9th column. I could see how I eliminated the 1s f5 & f6 ... but not as you mentioned the 1 in g4. It obviously had to be a momentary flash of brilliance (which now More...

Cont'd..... stubbornes and consult gb's sandbox to prepare for re-education. Must slip away and have a few quick ports beforehand though. This addiction has become an obsession; as if it's not already apparent. Oh, sorry, hi all. I think I have Mt. Rushhmore on the screen.