dailysudoku.com

SL · Guest

Appear not an unique answer.
(3, Cool

can be appeared in (r8c5, r8c9,r9c5,r9c9).

SL · Guest

keith · Posted: Tue Apr 11, 2006 4:55 am Post subject: Go fishing!!

The puzzle is unique, and quite interesting. After eliminating pinned values and using pairs, you get to:

Sarah · Joined: 04 Apr 2006 Posts: 6 Location: Brooklyn

Keith - I happened to solve it the first way you mentioned, eliminating the 9 from r9c6.
However, I'm curious about the rest of the terminology you're using ... x-wing, jellyfish, etc. Is there somewhere on this site to learn about that? Or a book?
Right now I simply follow the logic of the numbers, but it would be nice to understand what you're talking about. Laughing

Thanks!

keith · Posted: Tue Apr 11, 2006 9:02 pm Post subject:

Sarah,

To solve the Daily Sudoku puzzles you need to know about forced squares, pinned squares, pairs and triples, and intersections.

This logic

Marty R. · Posted: Tue Apr 11, 2006 9:28 pm Post subject:

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

Marty,

To form an x-wing, either both rows have only two cells with the candidate (the columns can have more) and those 4 cells line up in two columns or both columns have only two cells with the candidate (then the rows can have more) and those 4 cells must line up in two rows. After all, if there were only two occurrences of the number in both the rows and the columns (all of which would form the x-wing), where would one make exclusions?

keith · Posted: Tue Apr 11, 2006 10:35 pm Post subject:

Marty,

The X-wing starts with two possibilities in each of two rows (or columns). That line up. The result is eliminations in columns (or rows), so you end up with an X-wing rectangle that has possibilities at its corners, with solutions only on one diagonal, and no other possibilities in the rectangle's rows and columns.

Take at look at SadMan's explanation. And, there are SadMan puzzles that use the technique.

http://www.sadmansoftware.com/sudoku/technique6.htm

It took me a long time to understand this stuff: It was the definition of strong (and weak) links that was most helpful for me.

Keith

alanr555 · Posted: Wed Apr 12, 2006 1:15 am Post subject:

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

I think forced squares and pinned squares are other names for naked and hidden singles, although I'm not sure which is which.

SL · Guest

Keith,

You're right.
I'ven't carefully checked my answer. Sorry.

Marty R. · Posted: Wed Apr 12, 2006 3:57 pm Post subject:

keith · Posted: Wed Apr 12, 2006 8:58 pm Post subject: Terminology

Alan,

I am afraid I am using some unfamiliar terminology (or terminology unfamiliar to some).

By "square" I mean "cell". We can use SadMan as a decoder ring:

http://www.sadmansoftware.com/sudoku/techniques.htm

Go there to see what is meant by his term, you can translate my terms to yours.

(Keith = SadMan)

Forced square = Naked single

Pinned square = Hidden single

Intersections = Block and column / row interactions (= locked candidates, a term used by Marty)

Pair, triple = Naked and hidden subsets

I believe that all Daily Sudoku can be solved with only these techniques. (I would be delighted if the Daily Sudoku became more difficult.)

The terminology I use is from Robert Woodhead's Sudoku Susser Manual, I did not make it up.

Keith

keith · Posted: Wed Apr 12, 2006 9:36 pm Post subject: Another two-link

I am afraid I have to make another observation about this puzzle.

I a previous message, I pointed out an X-wing, which occurs when two strong links line up to form a rectangle. There is degraded form, where two strong links line up only at one end.

Here is our puzzle:

TKiel · Joined: 22 Feb 2006 Posts: 292 Location: Kalamazoo, MI

This is known as 'multiple colouring', which is merely two (or more) different conjugate (what you refer to as a strong link) chains linked on one end. They then function just like a single conjugate chain, in that any cell or cells that see both ends of the chains can be excluded.