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  Topic: "Coloring"
David Bryant

Replies: 5
Views: 39649

PostForum: Other puzzles   Posted: Tue Oct 17, 2006 12:56 am   Subject: Well, ...
Hi, Paladin! Haven't heard from you in quite a while.

You've reached a valid conclusion, but I can't quite follow your logic. Here's the problem.

r1c4 (+) --> r1c5 --> r7c5 --> r9c6 --> ...
  Topic: Another "technique" added to V Hard?
David Bryant

Replies: 1
Views: 30935

PostForum: General discussion   Posted: Fri Oct 13, 2006 11:04 am   Subject: I found an X-Wing
Hi, George!

We'll have to ask SamGJ to weigh in here about adding new techniques. I don't think you need to use anything beyond X-Wings to solve his puzzles, yet, but I'm not certain.

On the puzzle ...
  Topic: What's the logic behind remote naked pairs
David Bryant

Replies: 2
Views: 40035

PostForum: General discussion   Posted: Thu Oct 05, 2006 3:02 pm   Subject: It depends ...
Hi, Kowloon!

I'm not certain I understand your question, but maybe this is what you're asking about.
46+ . . . . . * . .
. . . . . . . . ...
  Topic: Aug 26 help please
David Bryant

Replies: 4
Views: 32006

PostForum: Daily Sudoku puzzles   Posted: Tue Oct 03, 2006 11:55 pm   Subject: Hidden pair in column 3
Hi, Kathy!

If you look closely you'll find a "hidden pair" {4, 5} in column 3 -- specifically, in r2c3 and r8c3. So the only spot in row 2 where the "9" can possibly fit is at r2c4.

Oh -- I often fi ...
  Topic: Sept. 28th Nightmare
David Bryant

Replies: 7
Views: 48295

PostForum: Other puzzles   Posted: Sat Sep 30, 2006 7:49 pm   Subject: Terminology
I've always thought of a constellation as an XY-chain (bivalue cells only) but this one passes through a cell that is solved (r7c6) and one that has 3 candidates (r5c8). Am also wondering if the 'alph ...
  Topic: Sept. 28th Nightmare
David Bryant

Replies: 7
Views: 48295

PostForum: Other puzzles   Posted: Sat Sep 30, 2006 1:46 pm   Subject: 5-star constellation
That's a very nice analysis, Matt. I particularly like the way you noticed how the two "X-Wings" intersect each other ... I missed that entirely, although I did find the same "anomaly" when I worked t ...
  Topic: Sep 29 - Logic behind an elimination?
David Bryant

Replies: 5
Views: 43288

PostForum: Daily Sudoku puzzles   Posted: Fri Sep 29, 2006 5:52 pm   Subject: Have you learned the "X-Wing"?
Hello, Blackwood!

The short answer is that you have an "X-Wing" formation in columns 1 and 6, on digit 7. In other words, since there are only two places to fit a "7" in column 1 (at r6c1 or r9c1) an ...
  Topic: Squiggly Sun Sep 24 2006
David Bryant

Replies: 3
Views: 160379

PostForum: Daily Sudoku Squiggly puzzles   Posted: Thu Sep 28, 2006 4:12 pm   Subject: Check this explanation
Hi, wfbeach!

I don't think there are two solutions. Maybe you noticed the same thing Louise56 was worried about ... check out [url=http://www.dailysudoku.com/sudoku/forums/viewtopic.php?t=1541]this p ...
  Topic: DB Saturday Puzzle - September 23, 2006
David Bryant

Replies: 34
Views: 148949

PostForum: Other puzzles   Posted: Sun Sep 24, 2006 6:53 pm   Subject: In defense of "nishio"
"A rose by any other name would smell as sweet."
The original description/method of nishio is the following: For a grid focused on a single digit. Assume that digit occupies a certain start cell. If, ...
  Topic: X-Wing & XY -Wing
David Bryant

Replies: 12
Views: 95941

PostForum: General discussion   Posted: Sun Sep 24, 2006 3:19 am   Subject: Play it again, Sam ...
Hi, Jake! Thanks for writing back. And thanks for the diagram. Specific examples are easier to follow than abstract explanations.
1xx|x1x|xx1
xxx|x1x|xx1
1xx|x11|1xx
-----------
xxx|xxx|xxx
xxx|x11|1x ...
  Topic: DB Saturday Puzzle - September 23, 2006
David Bryant

Replies: 34
Views: 148949

PostForum: Other puzzles   Posted: Sun Sep 24, 2006 12:00 am   Subject: What an interesting thread!
Wow! We have a very good discussion going this time. Thanks for posting this puzzle, Keith.
The original name for the "empty rectangle" was "hinge", which I think is more descriptive. You will find mo ...
  Topic: DB Saturday Puzzle - September 23, 2006
David Bryant

Replies: 34
Views: 148949

PostForum: Other puzzles   Posted: Sat Sep 23, 2006 8:00 pm   Subject: Look at "Nishio" / "Empty Rectangle"
... but there might be a more sophisticated solution which eludes me.
At this point in the puzzle there are a couple of "Nishio" moves that will solve it.
*------------------------------------------- ...
  Topic: X-Wing & XY -Wing
David Bryant

Replies: 12
Views: 95941

PostForum: General discussion   Posted: Fri Sep 22, 2006 10:32 pm   Subject: Which are you asking about?
Hi, Jake!

I'm a little confused by your post. Are you asking abou the "X-Wing" pattern? Or about the "XY-Wing"? Since you mentioned a rectangle, I suppose you're asking about the "X-Wing".

The first ...
  Topic: If you want to learn about fishing...
David Bryant

Replies: 16
Views: 99753

PostForum: Other puzzles   Posted: Thu Sep 21, 2006 6:52 pm   Subject: It's a finned X-Wing
Did you note the squirmbag (so called per Marty above -- a five-level x-wing I think) on the 2s removing the 2 from the {127} in r9c2 and leaving a bivalue cell. I am trying like heck to make that cri ...
  Topic: If you want to learn about fishing...
David Bryant

Replies: 16
Views: 99753

PostForum: Other puzzles   Posted: Thu Sep 21, 2006 12:01 am   Subject: Well, maybe it wasn't so basic ...
Hi, Matt!

You're right -- I did have to depend on a "finned swordfish" to eliminate the "5" at r2c5. And having a pair in that cell is essential to the forcing chains I found. I guess the "finned swo ...
  Topic: If you want to learn about fishing...
David Bryant

Replies: 16
Views: 99753

PostForum: Other puzzles   Posted: Wed Sep 20, 2006 10:12 pm   Subject: Using chains to solve this one
Here's how I solved this puzzle. The first time through I concentrated on r4c5; going over it again, I noticed that it's easier to work from r5c2. Basic stuff got me here.
*--------------------------- ...
  Topic: If you want to learn about fishing...
David Bryant

Replies: 16
Views: 99753

PostForum: Other puzzles   Posted: Wed Sep 20, 2006 6:01 pm   Subject: This is a hard one
Hi, Matt!

I did solve this puzzle by concentrating on two "double-implication chains". The first one started from r4c5, and the second one (later) started from r6c5. I'll have to reconstruct it befor ...
  Topic: challenging puzzle looking for help 1 through 9
David Bryant

Replies: 1
Views: 31085

PostForum: General discussion   Posted: Wed Sep 20, 2006 1:38 pm   Subject: It can't be done
Hi, Dan!

That's not a sudoku puzzle. It sounds like a magic square.

Clearly if it's a 3x3 square it's impossible. Since the sum of the digits 1 - 9 is 45, and every digit would be included in two su ...
  Topic: Naked singles on Sudoku
David Bryant

Replies: 2
Views: 27311

PostForum: Daily Sudoku puzzles   Posted: Tue Sep 19, 2006 1:30 pm   Subject: Poorly phrased question
Hi, Jeff!

I'm not sure I understand your question, but I'll give the best answer I can.

The only way to "solve" a cell in a sudoku puzzle is to reduce it to the status of either a hidden single or a ...
  Topic: Brown Belt 9
David Bryant

Replies: 2
Views: 32034

PostForum: Other puzzles   Posted: Sun Sep 17, 2006 1:48 pm   Subject: Line/Box interaction
Hi, Pete!

The hint relies on "line/box interaction".

The "3" in the lower right 3x3 box must lie in column 7. Therefore there cannot be a "3" at r1c7, leaving "2" as the sole candidate. dcb
 
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