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by **claudiarabia** » Thu Dec 28, 2006 5:51 pm

udosuk wrote:Claudia, your puzzle isn't the one of Carcul's riddle... It's another one from wapati, which Carcul just solved casually with his usual "complex forcing chains"...

Carcul's riddle is from this puzzle, where you've already spotted a nice xy-wing... Carcul just wanted us to solve it using uniqueness patterns only...

But what is TITILA? In the puzzle where I found the xy-wing, Carcul spoke of ATILA. But about TITILA I didn't find any deep explaination.

Claudia

by **Carcul** » Thu Dec 28, 2006 8:30 pm

Claudiarabia wrote:And now comes the TITILA: I suppose it means a contradiction; that a cell will stay empty, because it’s values are to be seen in the surrounding cells. The empty cell in our case is r8c5, while we put it’s candidates already in the cells to be seen in the surrounding of r8c5, i.e. the 3 in r7c4, 4 in r7c5, 2 in r5c5.

Wrong. You should also check your grid, because there is something wrong in it (compare with the original post: r2c4 is "4", not "6").

"TITILA" means Two Incompatible Two Incompatible Loops Argument: in other words, instead of one TILA we have two TILA, but it happens that they are incompatible with each other - the conclusion of one is in conflict with the conclusion of the other. So the hypothesis that originated this conflicting situation (in this case, r3c7 not "3") must be false.

Carcul

by **wapati** » Fri Dec 29, 2006 11:00 pm

Busy puzzle for patterns. There is a sword but other methods may remove it. <sigh>

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

by **daj95376** » Fri Dec 29, 2006 11:44 pm

wapati wrote:Busy puzzle for patterns. There is a sword but other methods may remove it. <sigh>

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

A nice Templates example of where one assignment, [r5c7]=1, is what's really needed.

Code: Select all: *-----------------------------------------------------------* | 159 29 7 | 15 1259 3 | 8 6 4 | | 159 8 4 | 7 6 129 | 259-1 159 3 | | 6 239 359 | 8 1259 4 | 7 1259 159 | |-------------------+-------------------+-------------------| | 59 7 1 | 3 4 8 | 6 59 2 | | 3 4 59 | 2 59-1 6 |!159 7 8 | | 2 6 8 | 15 7 19 | 3 4 59-1 | |-------------------+-------------------+-------------------| | 4 139 2 | 6 13 5 | 9-1 8 7 | | 7 19 69 | 4 8 12 | 259-1 3 1569 | | 8 5 36 | 9 123 7 | 4 12 16 | *-----------------------------------------------------------*

However, a nice Sashimi Swordfish is present to cause an elimination and force the necessary assignment.

Code: Select all: # Sashimi Swordfish r369\c(456)89 *-----------------------------------------------------------* | 159 29 7 | 15 1259 3 | 8 6 4 | | 159 8 4 | 7 6 129 | 1259 159 3 | | 6 239 359 | 8 *1259 4 | 7 *1259 *159 | |-------------------+-------------------+-------------------| | 59 7 1 | 3 4 8 | 6 59 2 | | 3 4 59 | 2 59-1 6 |!159 7 8 | | 2 6 8 |#15 7 #19 | 3 4 *159 | |-------------------+-------------------+-------------------| | 4 139 2 | 6 13 5 | 19 8 7 | | 7 19 69 | 4 8 12 | 1259 3 1569 | | 8 5 36 | 9 *123 7 | 4 *12 *16 | *-----------------------------------------------------------*

Note: After trying so hard to teach me the difference, ronk will kill me if I screw this up and this Swordfish is finned instead of Sashimi.

by **wapati** » Sat Dec 30, 2006 12:59 am

daj95376 wrote:
Code: Select all
# Sashimi Swordfish r369\c(456)89 *-----------------------------------------------------------* | 159 29 7 | 15 1259 3 | 8 6 4 | | 159 8 4 | 7 6 129 | 1259 159 3 | | 6 239 359 | 8 *1259 4 | 7 *1259 *159 | |-------------------+-------------------+-------------------| | 59 7 1 | 3 4 8 | 6 59 2 | | 3 4 59 | 2 59-1 6 |!159 7 8 | | 2 6 8 |#15 7 #19 | 3 4 *159 | |-------------------+-------------------+-------------------| | 4 139 2 | 6 13 5 | 19 8 7 | | 7 19 69 | 4 8 12 | 1259 3 1569 | | 8 5 36 | 9 *123 7 | 4 *12 *16 | *-----------------------------------------------------------*

Note: After trying so hard to teach me the difference, ronk will kill me if I screw this up and this Swordfish is finned instead of Sashimi.

Good job daj. I missed that sword entirely.

In plain english, Sashami is when an expected candidate is missing for that pattern. 1 or 2 fins are added.

Finned means the pattern is there but 1 or 2 added "fins" exist, in one box (natural 3X3).

Edited to remove question as to whether a fin is required. It is.

by **wapati** » Sat Dec 30, 2006 1:02 am

daj95376 wrote:A nice Templates example of where one assignment, [r5c7]=1, is what's really needed.

Daj, when you say "nice Templates example" is this anything like
"backdoor"?

By that I think I mean a cell that if solved leaves a puzzle "trivial".

by **daj95376** » Sat Dec 30, 2006 1:23 am

wapati wrote:
daj95376 wrote:A nice Templates example of where one assignment, [r5c7]=1, is what's really needed.

Daj, when you say "nice Templates example" is this anything like
"backdoor"?

By that I think I mean a cell that if solved leaves a puzzle "trivial".

No, Templates is a frowned-upon method that produces some spectacular results at times. It's mentioned in Mike Barkers list of solving techniques ... at the very bottom.

I used it recently in my puzzle generator and produced some puzzles that received some interesting attention for having difficult fish embedded in them.

by **ronk** » Sat Dec 30, 2006 1:39 am

daj95376 wrote:After trying so hard to teach me the difference, ronk will kill me if I screw this up and this Swordfish is finned instead of Sashimi.

Lots of laughs! It looks like sashimi to me too, so you get to live.

But I'm disappointed that you missed the smaller sashimi x-wing r59\c57 plus fin r9c89.

by **daj95376** » Sat Dec 30, 2006 1:43 am

wapati wrote:Good job daj. I missed that sword entirely.

Code: Select all: # Well, there's always this Finned X-Wing on <5> # Colors and Empty Rectangle also handles this elimination *-----------------------------------------------------------* | 159 29 7 | 15 1259 3 | 8 6 4 | |*159 8 4 | 7 6 129 |#1259 *159 3 | | 6 239 359 | 8 1259 4 | 7 129-5 159 | |-------------------+-------------------+-------------------| |*59 7 1 | 3 4 8 | 6 *59 2 | | 3 4 59 | 2 159 6 | 159 7 8 | | 2 6 8 | 15 7 19 | 3 4 159 | |-------------------+-------------------+-------------------| | 4 139 2 | 6 13 5 | 19 8 7 | | 7 19 69 | 4 8 12 | 1259 3 1569 | | 8 5 36 | 9 123 7 | 4 12 16 | *-----------------------------------------------------------*

Code: Select all: # Or this finned Kraken Swordfish on <9> *-----------------------------------------------------------* |#159 *29 7 | 15 *1259 3 | 8 6 4 | | 159 8 4 | 7 6 129 | 1259 159 3 | | 6 23-9 359 | 8 1259 4 | 7 1259 159 | |-------------------+-------------------+-------------------| | 59 7 1 | 3 4 8 | 6 59 2 | | 3 4 #59 | 2 *159 6 |*159 7 8 | | 2 6 8 | 15 7 19 | 3 4 159 | |-------------------+-------------------+-------------------| | 4 *139 2 | 6 13 5 |*19 8 7 | | 7 19 69 | 4 8 12 | 1259 3 1569 | | 8 5 36 | 9 123 7 | 4 12 16 | *-----------------------------------------------------------*

ronk: You should know me well enough by now to know that I miss a lot of things ... BUT ... I have fun in the process!

by **daj95376** » Sat Dec 30, 2006 1:50 am

ronk wrote:Lots of laughs! It looks like sashimi to me too, so you get to live.

Whew, that's a relief.

ronk wrote:But I'm disappointed that you missed the smaller sashimi x-wing r59\c57 plus fin r9c89.

Nice catch. Although those eliminations were among those indicated by Templates, I didn't investigate them because they wouldn't have led to [r5c7]=1 -- my true objective.

BTW: I probably would have missed it anyway.

by **wapati** » Sat Dec 30, 2006 10:15 pm

This one is pretty easy as a pattern but it has a Unique-Loop,
which is a method I don't yet use/know.

At the point where I would use a Skyscraper/Sashami-x/turbot there is also a "classic" Turbot and a Unique Loop. The others make the same elimination, the Loop I don't understand.

So, I'd be pleased if someone explained the loop.

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

(Edited for a typo)

by **wapati** » Sat Dec 30, 2006 10:27 pm

An xyz and a Swordfish. (I like swordfish!)

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

by **ravel** » Sat Dec 30, 2006 11:09 pm

wapati wrote:This one is pretty easy as a pattern but it has a Unique-Loop,
which is a method I don't yet use/know.
...
So, I'd be pleased if someone explained the loop.

Unique loops are a subset of BUG Lite.

This is Nicolas Juillerat's (Sudoku Explainer) explanation of the UL in this puzzle:
The cells R7C4,R9C4,R9C7,R8C7,R8C3,R7C3 form a Unique Loop with the values 7 and 8. There are exactly two ways of placing the values 7 and 8 in the cells of the Unique Loop, forming two possible configurations. In both configurations, each row, column or block touched by the Unique Loop contains each of the two values 7 and 8 exactly once. As a result, if one of these two configurations were part of the solution, it could then be replaced by the other one to get a second valid solution.

(One of the 5's in the 6 cells must be true, otherwise they form a deadly pattern which does not allow a unique solution, so you can eliminate all 5's that see both of the two 5's).

by **wapati** » Sat Dec 30, 2006 11:26 pm

ravel wrote:Unique loops are a subset of BUG Lite.

LOL, yep, and BUGLITE is a subset of BUG.

I saw the SE explaination, just don't get it.

Thanks, Ravel, I will re-read SE and hope it makes more sense!

by **wapati** » Sat Dec 30, 2006 11:27 pm

Another Swordfish, with xy-wing.

Mmm-Mmmm, swordfish is tasty!

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

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Re: Carcul's TITILA