The New Sudoku Players' Forum

by **ravel** » Sat Feb 24, 2007 1:42 pm

Carcul wrote:[r9c7]-5-[r7c5689]-2-[r8c7]=2=[r4c7](-2-[r6c89]-6-[r6c3]=6=[r8c3])-2-
-[r4c16]-5-[r89c1]=5=[r9c2]-5-[r9c7], => r9c7<>5 and the puzzle is solved.

I recommend to write it as
[r9c7]-5-[r89c2|r8c3]=5=[r9c2]-2-[r9c7]
Otherwise it is too obvious for nearly everybody

by **Carcul** » Sat Feb 24, 2007 1:44 pm

Wapati wrote:I was going to toss this one, no big fish. It is quite hard and I think it deserves attention.

Code: Select all: *--------------------------------------------------------* | 2 45 3457 | 47 1 67 | 39 4569 8 | | 47 348 9 | 5 247 2678 | 1 246 234 | | 1 6 458 | 3 9 28 | 24 7 245 | |------------------+------------------+------------------| | 3 7 1 | 9 8 4 | 6 25 25 | | 6 489 48 | 2 3 5 | 7 49 1 | | 59 245 245 | 17 6 17 | 8 3 49 | |------------------+------------------+------------------| | 59 1 2457 | 6 247 3 | 24 8 2479 | | 47 234 6 | 8 247 9 | 5 1 2347 | | 8 249 2347 | 147 5 127 | 39 249 6 | *--------------------------------------------------------*

1. [r2c5]-7-[r78c5]-2,4-[r9c46], => r2c5<>7.

2. [r1c2](-4-[r1c4]=4=[r9c4]-4-[r7c5])-4-[r25c2]-9-[r9c2]=9=[r9c8]-9-[r7c9]=9|5=[r3c9]-5-[r3c3]=5=[r1c2], => r1c2<>4 and the puzzle is solved.

Carcul

by **ravel** » Sat Feb 24, 2007 2:22 pm

With [r1c2]-4-[r25c2]-9 (suppose by use of the UR 17) there is obviously a shorter chain.

by **wapati** » Sat Feb 24, 2007 10:44 pm

This one is hard with patterns. SE rates it not too bad, using chains and a cycle.

Code: Select all: . 5 . | . . . | . . 2 3 . . | . . 2 | 9 7 . . . 7 | . . 5 | 1 3 . --------------------- . . . | . 7 8 | 6 2 . . . . | 4 . 9 | . . . . 7 5 | 1 2 . | . . . --------------------- . 6 4 | 3 . . | 2 . . . 8 1 | 2 . . | . . 3 9 . . | . . . | . 4 .

by **wapati** » Sun Feb 25, 2007 12:42 am

Too many givens, perhaps. Hard to solve though!

Code: Select all: 6 . 4 | . 3 . | . 7 . . 5 . | 7 . 4 | . . 2 7 . . | 8 . . | 4 . . --------------------- . 1 7 | 5 . . | . 4 . 2 . . | . . . | . . 7 . 6 . | . . 8 | 2 1 . --------------------- . . 6 | . . 9 | . . 5 1 . . | 6 . 5 | . 2 . . 2 . | . 8 . | 1 . 4

by **wapati** » Sun Feb 25, 2007 1:27 am

2 less givens, a bit easier. (Not easy, tho)

Code: Select all: . . 4 | 3 . . | 1 . 2 . . . | . . . | . 6 . 3 . 6 | . . 2 | 9 . 4 --------------------- 6 . . | 7 8 . | 5 . . . . . | 1 . 3 | . . . . . 5 | . 2 9 | . . 1 --------------------- 9 . 1 | 2 . . | 3 . 6 . 6 . | . . . | . . . 2 . 7 | . . 6 | 4 . .

by **wapati** » Mon Feb 26, 2007 8:05 am

There are a few Sashimi Swords to deal with.

Code: Select all: 1 2 . | . 4 . | . . . 7 4 . | 9 . 5 | . . . . . 9 | . . 2 | . . . --------------------- . 8 . | . 3 . | 9 1 . 6 . . | 4 . 9 | . . 5 . 9 1 | . 2 . | . 4 . --------------------- . . . | 2 . . | 3 . . . . . | 3 . 1 | . 5 9 . . . | . 9 . | . 2 4

by **Carcul** » Mon Feb 26, 2007 11:06 am

Wapati wrote:This one is hard with patterns. SE rates it not too bad, using chains and a cycle.

Code: Select all: *-------------------------------------------------------------* | 168 5 689 | 6789 13468 3467 | 48 68 2 | | 3 14 68 | 68 14 2 | 9 7 5 | | 268 249 7 | 689 468 5 | 1 3 468 | |-------------------+--------------------+--------------------| | 14 39 39 | 5 7 8 | 6 2 14 | | 1268 12 268 | 4 36 9 | 3578 15 178 | | 468 7 5 | 1 2 36 | 348 89 489 | |-------------------+--------------------+--------------------| | 57 6 4 | 3 89 17 | 2 15 89 | | 57 8 1 | 2 469 46 | 57 69 3 | | 9 23 23 | 678 5 167 | 78 4 1678 | *-------------------------------------------------------------*

[r5c7]=3=[r6c7]=4=[r1c7](-4-[r3c9])-4-[r1c6]=4=[r8c6]-4-[r8c5]=4=
=[r3c5]-4-[r2c5]-1-[r2c2]=1=[r5c2]-1-[r5c89](-5-[r5c7])-5-[r7c8]-1-
-[r9c9]-6-[r8c8]-9-[r6c8](-8-[r5c7])-8-[r5c9]-7-[r5c7], => r5c7<>5,7,8 => r5c7=3 and the puzzle is solved.

Carcul

by **ravel** » Mon Feb 26, 2007 12:04 pm

Please explain [r8c5]=4=[r3c5]-4 (why not r2c5 ?)

by **wapati** » Mon Feb 26, 2007 4:48 pm

Finned-x, finned sword and xyz patterns.

Code: Select all: . 7 6 | . . 9 | . . . 1 8 3 | . 2 . | . . . 5 4 . | . . . | . . . --------------------- . . . | . 1 4 | . . 2 . 5 . | 3 . 2 | . 4 . 9 . . | 6 5 . | . . . --------------------- . . . | . . . | . 1 5 . . . | . 3 . | 4 9 7 . . . | 7 . . | 3 2 .

by **wapati** » Tue Feb 27, 2007 6:25 am

This is the hardest puzzle I have generated, using Ruud's Soducue Cue,
that I can solve with patterns.

I have a question about UR, I used it here in an odd way, and I ask whether it is valid, or I got lucky!

Original:

Code: Select all: . . 4|. . .|9 . . . 5 .|. 6 1|2 . . 8 . .|9 . .|. 6 7 -----+-----+----- . . 8|. 1 .|. 9 . . 7 .|5 . 6|. 3 . . 1 .|. 9 .|5 . . -----+-----+----- 7 4 .|. . 5|. . 9 . . 2|7 3 .|. 5 . . . 5|. . .|7 . .

I chewed at it and got to this:

Code: Select all: .---------------.---------------.-------------------. | 236 236 4 | 238 7 238 | 9 1 5 | | 9 5 7 | 34 6 1 | 2 48 348 | | 8 23 1 | 9 5 234 | 34 6 7 | :---------------+---------------+-------------------: | 5 236 8 | 234 1 7 | 46 9 246 | | 24 7 9 | 5 24 6 | *18 3 *18 | | 2346 1 36 | 2348 9 238 | 5 7 246 | :---------------+---------------+-------------------: | 7 4 36 | 16 28 5 | 136 28 9 | | 16 89 2 | 7 3 49 | *18+46 5 *18+46| | 136 89 5 | 16 248 249 | 7 248 136 | '---------------'---------------'-------------------'

Looking at the 46s revealed in r8c79 can I say that r4c9 must be 2?

What would I call that?

by **wapati** » Tue Feb 27, 2007 6:58 am

Next hardest Puzzle that Ruud has made for me, that I can solve.

SE does like it better. All patterns without fins!

Code: Select all: . . . | . 6 . | . 1 8 . . . | . . 2 | . 3 9 . . . | 1 . 9 | . . . --------------------- . . 4 | . 2 . | 1 8 . 6 . . | 8 . 4 | . . 7 . 5 2 | . 1 . | 4 . . --------------------- . . . | 2 . 7 | . . . 2 8 . | 6 . . | . . . 1 7 . | . 3 . | . . .

by **udosuk** » Tue Feb 27, 2007 7:59 am

wapati wrote:I chewed at it and got to this:

Code: Select all
.---------------.---------------.-------------------. | 236 236 4 | 238 7 238 | 9 1 5 | | 9 5 7 | 34 6 1 | 2 48 348 | | 8 23 1 | 9 5 234 | 34 6 7 | :---------------+---------------+-------------------: | 5 236 8 | 234 1 7 | 46 9 246 | | 24 7 9 | 5 24 6 | *18 3 *18 | | 2346 1 36 | 2348 9 238 | 5 7 246 | :---------------+---------------+-------------------: | 7 4 36 | 16 28 5 | 136 28 9 | | 16 89 2 | 7 3 49 | *18+46 5 *18+46| | 136 89 5 | 16 248 249 | 7 248 136 | '---------------'---------------'-------------------'

Looking at the 46s revealed in r8c79 can I say that r4c9 must be 2?

What would I call that?

I'm not sure you can do that... The UR of {18} just concludes that r8c79 must be {14|46|68} and because it doesn't have to be {46}, I don't see how you can deduce r4c9=2... :?:

by **re'born** » Tue Feb 27, 2007 9:27 am

wapati wrote:This is the hardest puzzle I have generated, using Ruud's Soducue Cue,
that I can solve with patterns.

I have a question about UR, I used it here in an odd way, and I ask whether it is valid, or I got lucky!

Original:

Code: Select all
. . 4|. . .|9 . . . 5 .|. 6 1|2 . . 8 . .|9 . .|. 6 7 -----+-----+----- . . 8|. 1 .|. 9 . . 7 .|5 . 6|. 3 . . 1 .|. 9 .|5 . . -----+-----+----- 7 4 .|. . 5|. . 9 . . 2|7 3 .|. 5 . . . 5|. . .|7 . .

I chewed at it and got to this:

Code: Select all
.---------------.---------------.-------------------. | 236 236 4 | 238 7 238 | 9 1 5 | | 9 5 7 | 34 6 1 | 2 48 348 | | 8 23 1 | 9 5 234 | 34 6 7 | :---------------+---------------+-------------------: | 5 236 8 | 234 1 7 | 46 9 246 | | 24 7 9 | 5 24 6 | *18 3 *18 | | 2346 1 36 | 2348 9 238 | 5 7 246 | :---------------+---------------+-------------------: | 7 4 36 | 16 28 5 | 136 28 9 | | 16 89 2 | 7 3 49 | *18+46 5 *18+46| | 136 89 5 | 16 248 249 | 7 248 136 | '---------------'---------------'-------------------'

Looking at the 46s revealed in r8c79 can I say that r4c9 must be 2?

What would I call that?

I agree with udosuk. The only exclusion I see related to that UR (without any chains) is that the strong link on 8 in c7 implies that r8c9<>1.

by **StrmCkr** » Tue Feb 27, 2007 9:50 am

notes.

the move he shows and tries to explained is identical to a move ive been working with and trying to explain (but failing misserably once again due to way to many digits to exlude.) to solve me and mikes 11.4 rated puzzle

the idea is:
two rectangles are directly linked and you can't check 4 values as either holds a corner of the rectangles in place, this reduces/identifies a single corner as the only plausable location of a single valid number not found in both rectangles.

in this case the 2.

# = 46 rectangle
* = 18 rectangle
% = corner with a number not held in either as 1468 are all directly locked together.

which leads to

r4c9 = 2

Code: Select all: .---------------.---------------.-------------------. | 236 236 4 | 238 7 238 | 9 1 5 | | 9 5 7 | 34 6 1 | 2 48 348 | | 8 23 1 | 9 5 234 | 34 6 7 | :---------------+---------------+-------------------: | 5 236 8 | 234 1 7 | 46# 9 246#% | | 24 7 9 | 5 24 6 | *18 3 *18 | | 2346 1 36 | 2348 9 238 | 5 7 246 | :---------------+---------------+-------------------: | 7 4 36 | 16 28 5 | 136 28 9 | | 16 89 2 | 7 3 49 | *18+46# 5 *18+46#| | 136 89 5 | 16 248 249 | 7 248 136 | '---------------'---------------'-------------------'

The New Sudoku Players' Forum

CHAINS, not required. Good puzzles.