Sudoku Puzzles

The MILL BAKEHOUSE on the cnr of Nolfolk St and Marine Terrace, Freo at 9.30am Saturday, Nov 11th - it's booked 'under' 'Billy'.
Hope you can make it...x

typical Australian scenery - good one as usual fi.

Interesting.

Have a great day everyone.

5:51 Maen

8:34 MAEN It's not very tough if I'm under 10 (or 20) minutes...

Desolate.

Probably not a good place to have car trouble ...

The logic in this puzzle was opposite everything I picked.

Interesting photo.

took exactly 14 minutes to fill the grid and see fi's pic..yes not very tough..just methodical solving..happy to end the day this way..
cheers

On November 4, 2006, SS asked:
I've been battling with these tough puzzles, and can't seem to get through most of them without guessing. To all the experts.. is there any technique for identifying forbidding chains? I can understand the logic behind it if I see a proof, but I cannot spot one on More...

On November 3, 2006 'observer' from USA answered SS as follows:
to SS from England: it's a near certainty that the
'experts' use software to locate forbidding chains.
The regularity of the lexical style of the proofs
plus the speed of production add weight to this claim. Write small More...

Hehe - 'observer' obviously answered on November 4, 2006 after the question posted by SS. Would be a neat trick to answer before the question, albeit not entirely inconsistent .... !!

Could be an interesting puzzle today. Will have to get to the puzzle later, though.....

mAen! Over an hour. Oh dear!

Wow... tough today, 1:28:22! Buchanan Hwy

22:38; Steve, the toughs can be solved without any guesses by filling in all boxes with possibilities. Then look for common numbers (am assuming that's what you call fcs) in 2,3,4 even 5 cells in 1 row/column/box. Once these many boxes have claimed the possible digits, remove these digits from More...

Thanks Shruti!
I appreciate the advice, although I do post proofs at this site on a somewhat regular basis. I was responding to a question posted by others. What I call 'fc's', is a particular type of technique, called 'forbidding chains'. An explanation of what these are can be found through More...

Sorry Steve, skimmed the msgs, posted a thought. You obviously know better.

58:52

Also, thanks for sending me to 'proofs'. Nice to know that my mommy approach has some technical jargon behind it!

Good afternoon to all! Why the burnoff Fi?

HalT: Was late last night.... Finish off what Anne left maybe?

'Or get down behind that small bush.

He hunkered down upon the ground,
But the gorilla saw him there,
Next thing you knew, he was bound,
To the gorrila's lair.

The gorilla took his camera,
The gorilla More...

Greg, cats off to you for taking the rhyme to a hilarious new level!

A worthy tough puzzle today:

1) Start 23, Unique Possibilities to (UP) 27.
2) Locked 7s at gi6 forbid ef6=7. UP 28.
3) Naked triplet f5=236, f6=23, f7=36 forbids f1=6, f3=26, f89=36. UP 29.
4) d7=5 == c7=5 -- c2=5 == de2=5 forbids d1=5.
5) i5=2 == f5=2 -- f5=6 == d5=6 -- d1-6 More...

Possible proof of tough sudoku of 11 08 06:
1) Start at 23 filled - the given puzzle. Unique Possibilities to 27 filled. (UP 27).
2) Locked 7's at gi6 forbids ef6=7 UP 28
3) Triple 236 at f567 forbids f3d45=2,f89=3,f1389=6 UP 29
4a) Locked 2's at ac4 forbids a5=2
4b) fc on 5's: More...

Hi Clark!
Similar proofs today, at least to get rid of that nasty 9 at i2. From there, perhaps we diverged a tad.

Good one Greg - thanks for finishing the poem I couldn't do last night.

C. Greg: That was great. I'm humbled.

A typo (minor):5d) triple 156 at abc3 forbids a1c2h3=5 and forbids a1b2gh3=6 and forbids gh3=1 UP 31

A revision: adds a set, but reduces proof rating:
6b) b5=3 == b2=3 -- a1=3 == a1=4 -- a5=4 == pair 39 at ab5 forbids ac4,dfhi5=3 could be shorter:
a5=9 == b5=9 -- b5=3 == b2=3 -- a1=3 More...

HalT: Humbled? Good gosh you started it! Didn't you want a finish? Waiting for the next one, but no pre-determined finish this time. Just go with the flow!

Canuk Greg: Well, actually I didn't start it; shruti From ca did. I just went with the flow. ;>)

Hi STEVE, CLARK & PAT,

for me and i think many many people came here : YOU ARE EXPERTS. your proofs help me how to solve puzzle better. i always try to solve puzzle by logic for myself - don't care timer, someone like to solve by guessing ... it's up to them. therefore, i think you no need More...

Easy tough today. Great photo, fi. Australia looks bleak, but interesting. I wish we practiced more burnoff here in California. Maybe we wouldn't have so many forest fires. One this year killed 5 firefighters. They caught the arsonist, though.

Steve: I can't always follow your proofs, but I just figure I have a lot to learn. You did teach me how to find hidden pairs.

I seem to have gotten my normal solution time down to about 20 minutes by looking for a column or row with a number that occurs only twice with each possibility in a different box AND filling in either of those cells with that number creates unique fills for an entire box, row or column. For some More...

maeN all. Burn off is a NT tradition predating the White fella. Some of it is done to prevent major bush fires which would be life threatening but some of it is to get rid of te spear grass which grows high and is not great fodder. If the timing is right and there is still moisture in the ground More...

Hi Clark,

Your excellent proof can be slightly simplified by eliminating step 16 (the unique rectangle thing), as the solution falls out without this step.

Whew, got his one after a couple of hours struggle, but without any special techniques, something like what Shruti said. However, I havent, unfortunaely, noted the actual way I went about doing it, and possibly I may not be able to repeat the process for the same tough problem of today!

SE=8.4