Sudoku Puzzles

Peaceful River looks serene..anyone know where this is?

am i first?!

No. Neither am I.

Lovely!!! Good Maen!

Well, at least I finished it.
Now can I go to the peaceful river?

Maen all. Nice sunset

It is indeed. Good for the last puzzle before bed. But where is it?!

1) Start at 23 filled - the given puzzle. Unique Possibilities to 26. (UP 26).
2) {f9=3 == d7=3 -- i7=3 ==i3=3}== i4=3 -- i4=7 == i5=7 -- f5=7 == f3=7 forbids f3=3
... matrix is more clear:
f9=3 d7=3
i3=3 i7=3 i4=3
0000 0000 i4=7 i5=7
f3=7 0000 0000 f5=7
Logic: More...

BTW - Simple Sudoku uses 12 sets to get stuck at 26 filled.

An interesting (to me any way) way to write step 2) above:
d3=7 == d5=7 -- i5=7 == i4=7 -- i3=3 == {colors3's at i3i7d7f9} forbids d3=3.

Have not thouroughly checked - there could easily be a depth 3 proof for today's puzzle.

49:04

Good Maen to all. Beautiful picture! Now let's all go for a canoe ride on that very peaceful-looking river!!

My proof is very similar to Steve's. My last step is a more compilcated version of his last step, but I've gotten so used to looking for the hard stuff over the last couple of days I've forgotten how to find the simple stuff :).

1) Start 23, UP to 26.
2) f3=3 -- i3=3 == i47=3, and f3=3 More...

A word about the matrix confiration in showing a proof - the way I see it. First, it is Andrei's idea, so I may butcher it.
To me, it is nothing more than the logic used when one eliminates possibilities with an N tuple, swordfish, etc (N tuple being pairs, triples, etc)
Those are not the More...

The first column being the one, by default, that one is trying to prove as containing at least one truth. Then, anything mutually forbidding by each of the possible truths in the first column is forbidden.

HI Clark - I really like the logic you used in your last step, irregardless of how complicated. Often times the illegal oddagons seem easy for me to see, albeit they are almost always superfluous to something shorter.

One last obvious note on the matrices that I did not specify. The matrix needs to be square:
Number of columns = Number of rows. Otherwise, the logic does not hold. (Although, technically, the matrix could have less rows then columns, but not more rows then columns.... cannot imagine that tidbit will be useful though!)

An illegal odd-agon could be viewed as simply a matrix that is a wrap around matrix(wrap around being important here), but it has less rows then columns, thus it has too many truths and must fail...( I know I said last note before - sorry!)

Hi Steve,
No I am not discouraged. I see that I must have had a problem with my set-up. Working on a program at the moment to help with that.
It is almost far enough to pass on, but not quite. Using Delphi.
Thanks for your good comments
Ciao John

I also see that everything up to hard is trivial. Just do them to pass the time.
It is also good to see that there are people who can even solve monsters in about 3-4 minutes, but not sure how they do it.

I seem to remember similar phenomena from the Rubrik cube ... sure there are people who can do it just like that. But mostly not.

hello all..nice to be back and more nice to have a tough that i could solve w/o much difficulty..
what more do i need to end the day..feels good and the pic of the lovely river is all the more rewarding.thanks for it whoever posted it..
cheers

The usual way!

I'd like to canoe there also. That is more water than I have seen in a long time,thanks.Its quite refreshing.

Steve -- I'm jealous of your ability to do the proofs, so I'll have to pick you up on your English -- irregardless is not a word!!

TO STEVE irregardless?

Sorry folks, but irregardless is in Webster's 3rd International Dictionary.

Would make a beautiful jigsaw puzzle.

i dont under stand all that garbage does it work ???? ijust think real hard and work work

12 mins without any planning, just looked any did what seemed right, would like to be fishing that river now

STEVE (and anyone else with a mathematical brain)I am trying to work out these tough ones without 'cheating' and guessing. BUT (excuse my ignorance) how do you start at 23? Where is the 23rd square? What grid system are you using? If you are going to take the time to enlighten me, please assume that I need a “Sudoku-Solutions-For-Dummies” type of explanation. Ta muchly!

It means - WHen you've filled in 23 squares - including the ones that you are given- eg today there are 23 filled for you to start with. With my calculations there are another 3 fairly straight forward ones- up to 26 ... etc. Hope this helps Mandie - and it keeps going up to 81 filled. Hints are not generally given for the straight forward fillings - jsut the tricky ones.

The Rows are numbered from 1 up to 9 from the bottom to the top. The columns are numbered abcdefghi from left to right. - So f3 is in the third row, sixth column. The blocks are refered to with a capital Bin front of the middle square in that block of 9 eg Bb2 is the bottom left block.
More...

That was also from me - Sorry.

FI thanks for that... I have copied and pasted it away for me to peruse when my brain is in a more mathematical frame.

It does seem that, given the mathematical nature of my comments, the use of a word with a double negative inside of it should be avoided. Regardless of that, 'tis been a long time since anyone has cared about my English usage. Thanks!

To Steve from Ohio

I replaced your step 2 with my double-chain method. Starting with d1=-3,+7, f3=+3,-7 it is easy to see f5=+7, f9=-3, d7=+3
Now if d7=+3, i7<>+3 and f3=+3, i3<>+3 so i4=+3
But f5=+7, i5<>+7, i4=+7 which is impossible.
The opposite chain must be all true so d1=3, f3=7, f9=3.

Hi JRD!
Very nice idea - the double chain method you show. Can you see that it uses exactly the same strong sets (plus some?) that I used? The benefit of the additional sets you use is that you get more solved cells immediately. Of course, those same cells solve easily after just one More...

An interesting aside:
If one where to use JRD's double chain investigation,
Any of the cells solved between up 26 and up 36 in today's puzzle will revert to the same contradiction if one assumes that cell does not equal what it actually equals. They may revert to a faster contradiction, but More...

Hi all..Don't usually comment on 'tough' but I have just come back from holidays and looked through the gallery and noticed my son Scott's photo appeared here on the 6th June. I read the comments and I thank you very much for the kind words. I think he is a spunk too but I maybe biased...lol... More...