Sudoku Puzzles

to Steve: I posted a solution to your puzzle on yesterday's archive - max chain depth 2 (but of course that is far from classical depth as the chain uses two almost hidden triples to forbid an almost naked triple. When the smoke clears a group premise stands triumphant and the rest is history.).

I believe I see people out there. Is this a controlled fire?

proof of today's easy:

1) Start with 22, UP 24
2) Naked Triple: e654=359 => ~e9821=359, UP 26
3) Locked: a321=8 => ~a8=8
4) Hidden Pair: bd7=78 => ~(b7=149, d7=39)
5) SwordFish: (bd7, bg5, dg3)=7 => ~(b96, b6, g6, d2)=7, UP 81

now to work

note: today's proof can be trimmed down to:

1) Start with 22, UP 23
2) Naked Triple: e654=359 => ~e9821=359, UP 27
3) SwordFish: (bd7, bg5, dg3)=7 => ~(b96, g6, d2)=7, UP 81

8:05 Maen

Natural or man-made fire?

Steve, the puzzle you created on 11 Oct had only eight lines. Did I miss something?

Interesting photo.

I am still waiting for more of my pictures to make an appearance!

Just wanted to thank those who take the time to post proofs. I've been solving these daily for about a year and find the 'hard' puzzles too easy and the 'tough' puzzles too tough. Thanks to the many proofs posted each day I'm learning my way through.

Makes me nervous, seeing that large flame and all that dry grass.

17:32

Daly River - 26:19, be better than yesterday...!

21:18

9:33 Maen

Hi Pat!
Thank you for taking the time to look at the puzzle I posted a few days ago!

I do not know if you looked at the proof that I posted for that puzzle, but it is similar to what you presented. The interaction of the Almost hidden triple and the Almost Almost locked set yields a Sue More...

To Halt ( and others)
I posted later that day a corrected version of the puzzle. Sorry about the early omission.

To Steve: Sorry, I checked the posts an hour or so after I saw your first entry. I should have gone back on the 12th to see if there were any additions. Thanks.

fi - you always seem to be in the right place at the right time with your camera. A friend of mine from badminton has just spent two weeks in Darwin and absolutely loved it. I hope to get there one day.

Alternative puzzle for 10/12/06:

001_000_700
040_700_006
570_001_090
006_030_ 000
020_800_003
100_007_020
007_000_500
010_400_008
400 _009_030

25 initial cells... but not too easy - let me know what you think!

Could someone please explain the concept of Swordfish...thnx

Hi Fred!
A swordfish is an elimination involving just one type of candidate. It is logically equivalent to a naked triple - but not obviously so.

A full swordfish configuration would be as follows:
A candidate is limited to 3 locations (or less) in either 3 rows or 3 columns. It can More...

10:15 that swordfish puzzle looks hard.

9.24
the sight of flames today is sending us all into a panic.... extreme fire danger with many burning out of control... and it is only mid october.

pretty easy several days in a row .... the lull before the storm????

How do you read the coordinates,

eg 1) Start with 22, UP 24
2) Naked Triple: e654=359 => ~e9821=359, UP 26

Can anyone assist. Thanks

Dry Season burns are a pretty common sight between April and June in NT. After the Wet - the spear grass is tall and dries out quickly. It has been common practice to burn since before the white man. Thought there are some benifits of teh burn including fire breaks, access and regrowth of edible More...

Hi G!
We use a coordinate system similar to algebraic chess board notation:
columns a thru i, left to right
rows 1 to 9, bottom to top
Thus, bottom left corner is a1, top right corner is i9.

benefits

Hi STEVE from Ohio,
Your puzzle today i think that is TOUGH. My brief to solve it (not proof):
1- Looked 7's => a5,e1,h2,i6 =7
2- i1 = 1 => h2,i2<>1, i1=2 => g1=1 => h2,i2<>1 then i1=1
3- g2=2,9 => g1=6, h3=4, g2=6 => h3=4 then g2=6, h3=4
4- i4==i3=9 - More...

I see the 2 and 8 in the middle. I see the naked triple. Then i see the 5 in the middle box under. but the 26th UP I don't see.

And then I don't understand the codes for:

Locked: a321=8 => ~a8=8

and: SwordFish: (bd7, bg5, dg3)=7 => ~(b96, b6, g6, d2)=7, UP 81
More...

Hi ttt!
I am not sure how you manged to solve the 7's. If you can show me how you did that, I would be in your debt.
Thanks!

At 24filled – note triple in e456 up to 26

IF b6=7- follow the trail of 7’s for 5 moves to find that Bb8 has no 7s.

Therefore b6=9 up to 29

If e9=7, b9=4, b5=7 leaving no 7s in Bb8 Therefore e2=7 up to 40

If c3=1, c2=4, c5=5, a6=7, g5=7 leaving no 7s in R3 Therefore c3=9

Up to 81

Hi STEVE from Ohio,
my 7's : a5==a6=7 - i6==i1=7 - e2==h2=7 ~ h5=7.
It is correct?

Today's puzzle was interesting and not too difficult. Thanks for posting it.

Hi ttt!
i1=7 -- e1=7, not e2... so I would say not correct.

Hi STEVE,
Yah...,thoughtless again. some Tough have chain as 7's on your puzzle, if break them then solve it. have technicque to do that? now, i know that have not yet, but why we don't think about that...i come back your puzzle again.

I also see the 2 and 8 and naked triple to get the 5 at D1, but what next?

Hi G, and thanks to Steve for the comment on the coordinate system in use. I share G's questions. I've figured out the coordnate system, and how strong and weak linkes are notated from the excellent 'forbidding chains for absolute beginners' through the 'Proofs' link below. But, as with G, I More...

start with 22 means that 22 cells are given. UP 24 means that with unique possibilities you can enter 2 more values.

But what drives me crazy is where the next number goes after 2 8, naked triple -> 5.

and why it is said that: Locked: a321=8 while in e3 there's another 8. then a3 can't be 8 or what??