The New Sudoku Players' Forum

by **ronk** » Fri May 31, 2013 11:51 am

denis_berthier wrote:In my view of Jk-Exocet, the S-cells are the most important part (I'll explain this in a further post).

Since strong inference sets "make the sudoku world go around", this shouldn't be a surprise to any participants in this thread. See Allan Barker's 2nd graphic in his 2009 post here.

As to your fish comment, I believe swordfish and x-wings have been mentioned in conjunction with JExocets several times in the past.

Website · by **denis_berthier** » Fri May 31, 2013 3:27 pm

ronk wrote:
denis_berthier wrote:In my view of Jk-Exocet, the S-cells are the most important part (I'll explain this in a further post).

Since strong inference sets "make the sudoku world go around", this shouldn't be a surprise to any participants in this thread.

As there are 3k + 6 CSP-variables / 2D-cells /sis involved in the pattern, I can't see how your remark can be relevant to my saying that the 3k ones associated with the S cells and Base Digits are the important ones.

Moreover, what I say can't be so obvious, as:
- it is totally opposite to champagne's view according to which the core of the pattern consists of the base and target cells;
- David's "mental model" was based on the JE band.

by **blue** » Fri May 31, 2013 5:47 pm

David P Bird wrote:
denis_berthier wrote:Hi David,

I can't see why the Q and R pairs should be in different blocks/boxes. Indeed, my proof works without this assumption.
I think the right condition is:
The two Object Cell Pairs (Q and R) occur in the same band as the Base Cell Pair (B) (the JE band) but not in the same block/box.

Wow! I've been working with a pair of blinkers on! I've been considering that the Braid Analysis constraints always had an important part to play in the pattern (although expressing them in Braiding terms has never been needed).

With the targets in the same box, these constraints go and are replaced by the more restrictive box ones, so I guess these cases will occur far less frequently.

Just as I was beginning to think I could see light at the end of the tunnel!

As long as this has come up, I should mention that there's no reason to restrict the target cells to the base cell band.
Here's an alternate proposal for the (core of the) pattern definition:

Code: Select all: *-------*-------*-------* | B B . | . . . | . . . | B = base cells | . . . | S . . | S . . | S = fish column cells | . . . | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | T : two S cells are designated as target cells | . . S | S . . | S . . | | . . S | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | Requirement: for each base digit, the candidates | . . S | S . . | S . . | in the S cells are restricted to two rows and the | . . S | S . . | S . . | target cells *-------*-------*-------*

Here's an example from champagne's "potential hardest" list.

Code: Select all: #9004 GP;H2447 98.7.......7.6.9....6.5....4......3..9...2..1...6..5..1.......4.3.....2...98..7.. +---------------------+-----------------------+--------------------+ | 9 8 12345 | 7 1234(B) 134(B) | 12346 1456 2356 | | 235 1245 7 | 1234 6 1348 | 9 1458 2358 | | 23 124 6 | 12349 5 13489 | 1234-8 1478 2378 | +---------------------+-----------------------+--------------------+ | 4 12567 1258 | 159 1789 1579 | 268 3 26789 | | 35678 9 358 | 345 3478 2 | 468 4678 1 | | 2378 127 123-8 | 6 134789 13479 | 5 4789 2789 | +---------------------+-----------------------+--------------------+ | 1 2567 258 | 2359 2379 35679 | 368 5689 4 | | 5678 3 458 | 1459 1479 145679 | 168 2 5689 | | 256 2456 9 | 8 1234 13456 | 7 156 356 | +---------------------+-----------------------+--------------------+ S S S Base cells: r1c56 S columns: c347 Target cells: r3c7, r6c3 XSudo output: 14 Truths = {1234C3 1234C4 1234C7 1N56} 18 Links = {1234r1 12r4 34r5 23r7 14r8 6n3 3n7 1234b2} 2 Eliminations --> r3c7<>8, r6c3<>8

Regards,
Blue.

Website · by **denis_berthier** » Fri May 31, 2013 6:02 pm

blue wrote:Here's an alternate proposal for the (core of the) pattern definition:

Code: Select all
*-------*-------*-------* | B B . | . . . | . . . | B = base cells | . . . | S . . | S . . | S = fish column cells | . . . | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | T : two S cells are designated as target cells | . . S | S . . | S . . | | . . S | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | Requirement: for each base digit, the candidates | . . S | S . . | S . . | in the S cells are restricted to two rows and the | . . S | S . . | S . . | target cells *-------*-------*-------*

Excellent, this discards all the unnecessary conditions.

by **champagne** » Fri May 31, 2013 6:59 pm

denis_berthier wrote:
Moreover, what I say can't be so obvious, as:
- it is totally opposite to champagne's view according to which the core of the pattern consists of the base and target cells;
- David's "mental model" was based on the JE band.

The exocet problematic in my view is very simple

The exocet as such is reduced to the base and the target(s).The common properties to any exocet are clear.

A key issue is "how do you establish the exocet proof".

Here, the JE exocet play a key role just because it is by far the most common exocet.

A third issue is on the solving side. Is there for that specific exocet pattern some solving shorts. Usually, such shorts are tightly linked to the "proof pattern".

The "abi loop" belongs to that third group.

The only common property for any exocet is the link between the base and the target.

by **champagne** » Fri May 31, 2013 7:06 pm

blue wrote:98.7.......7.6.9....6.5....4......3..9...2..1...6..5..1.......4.3.....2...98..7..

Base cells: r1c56
S columns: c347
Target cells: r3c7, r6c3

Hi blue,

Interesting example,

I had in mind one example of exocet with the target outside the band, It was not that one; either my memory is weak or you made a deeper search.

by **blue** » Fri May 31, 2013 7:29 pm

Hi champagne,

champagne wrote:I had in mind one example of exocet with the target outside the band, It was not that one; either my memory is weak or you made a deeper search.

I think it was this one: (not related to JExocet)

#1952 elev;1806 -- base: r13c6, targets: r2c9 r7c5
...4....94....923..8..2...4..6..3...8..59...2.......7.3..9....5..8..21...1...5...

Yes, I always wondered how you knew of that one, but not the others.

Regards,
Blue.

by **David P Bird** » Fri May 31, 2013 11:30 pm

Hi Blue,

blue wrote:Here's an alternate proposal for the (core of the) pattern definition:
Code: Select all
*-------*-------*-------* | B B . | . . . | . . . | B = base cells | . . . | S . . | S . . | S = fish column cells | . . . | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | T : two S cells are designated as target cells | . . S | S . . | S . . | | . . S | S . . | S . . | *-------*-------*-------* | . . S | S . . | S . . | Requirement: for each base digit, the candidates | . . S | S . . | S . . | in the S cells are restricted to two rows and the | . . S | S . . | S . . | target cells *-------*-------*-------*

Congratulations, very good work, but it results in potentially driving a horse and cart through this thread!

The dilemma it poses is that "recognisable pattern" once again. Restricting the base digits to absent givens in the band, makes looking for the signature pattern quite quick and knowing that the other two S lines must pass through targets in the same band makes the subsequent checks reasonably quick too. The potential returns for an advanced player conducting a JE search aren't just a few eliminations in two cells, but also various inferences that can be combined with other patterns. For your version I believe that mainly it will just be the eliminations on offer for a far bigger search effort. (This would also justify Denis' point regarding only counting the patterns that provide eliminations in any survey.)

The choice of the name "Junior Exocet" was fortuitous, because that leaves the door open to call your extended version "Advanced Exocet". However, it should be possible to allow the two targets in JExocet to be in the same box as per Denis' findings.

That's the way I would currently favour going, but I wait for other opinions.

David

by **Leren** » Sat Jun 01, 2013 12:42 am

David P Bird Wrote:
After basic and SK loop eliminations
Code: Select all
*----------------------*----------------------*----------------------* | <9> <8> 123 | <7> 56-12 5-3 | #123 2346 14 | | <6> 4 7 | #123-8 129 389 | <5> 239 189 | | #123 #123 <5> | 1238 <4> 69 | 1238 <7> 69 | *----------------------*----------------------*----------------------* | 1458 <7> 148 | 689 <3> 569 | 19 459 <2> | | 1238 123 <9> | <4> 257 578 | <6> 35 157 | | 2345 6 234 | 29 579 <1> | 379 <8> 4579 | *----------------------*----------------------*----------------------* | 1238 123 <6> | <5> 179 379 | <4> 29 789 | | 237 59 23 | 369 <8> 4 | 279 <1> 56 | | 1478 59 148 | 19 679 <2> | 789 56 <3> | *----------------------*----------------------*----------------------*

I think I can see another JE based elimination in this PM.

If r1c9 = 4 (a non-base digit) then a JE secondary equivalence r1c8==r2c4 would apply so r1c8 = 2 or 3;
If r1c9 <> 4 then r1c8 = 4;

Either way r1c8 <> 6

Leren

by **blue** » Sat Jun 01, 2013 1:30 am

Hi David,

I don't know if you noticed, but the example that I showed, has only one clue cell out of place -- a "would be" clue at r6c3, moved to r2c3. The base cell band is still deviod of base digit clues, and the 2 clues each for the base digits, are where they usually are.

I agree that there probably isn't much to be gained beyond the standard eliminations.

I wonder how that type of layout might fare in the "abi loop" game, though ?
I see that for the example puzzle, 4r1c5 can be eliminated (using UR considerations).
[ No time to look deeper, at the moment. ]

Regards,
Blue.

by **David P Bird** » Sat Jun 01, 2013 7:23 am

Leren wrote:
David P Bird Wrote:
After basic and SK loop eliminations
Code: Select all
*----------------------*----------------------*----------------------* | <9> <8> 123 | <7> 56-12 5-3 | #123 2346 14 | | <6> 4 7 | #123-8 129 389 | <5> 239 189 | | #123 #123 <5> | 1238 <4> 69 | 1238 <7> 69 | *----------------------*----------------------*----------------------* | 1458 <7> 148 | 689 <3> 569 | 19 459 <2> | | 1238 123 <9> | <4> 257 578 | <6> 35 157 | | 2345 6 234 | 29 579 <1> | 379 <8> 4579 | *----------------------*----------------------*----------------------* | 1238 123 <6> | <5> 179 379 | <4> 29 789 | | 237 59 23 | 369 <8> 4 | 279 <1> 56 | | 1478 59 148 | 19 679 <2> | 789 56 <3> | *----------------------*----------------------*----------------------*

I think I can see another JE based elimination in this PM.

If r1c9 = 4 (a non-base digit) then a JE secondary equivalence r1c8==r2c4 would apply so r1c8 = 2 or 3;
If r1c9 <> 4 then r1c8 = 4;
Either way r1c8 <> 6

Hi Leren, that's a good one!

It can be expressed as this AIC
(4)r1c8 = (4-1)r1c9 =[JE]= (123#2)r1c78 => r1c8 <> 6

But the strong derived inference will only hold when the box 2 target is in r2, as then r1c78 must contain the two true base digits. Therefore it seems a distinction must be made between be JEs with co-linear targets and those with diagonal ones when this inference is used.

David

by **champagne** » Sat Jun 01, 2013 7:43 am

Hi David,

analysis of the results is a long task.

here a first list of puzzles with possible things of interest for you

Hidden Text: Show

by **champagne** » Sat Jun 01, 2013 7:48 am

blue wrote:Hi champagne,

champagne wrote:I had in mind one example of exocet with the target outside the band, It was not that one; either my memory is weak or you made a deeper search.

I think it was this one: (not related to JExocet)

#1952 elev;1806 -- base: r13c6, targets: r2c9 r7c5
...4....94....923..8..2...4..6..3...8..59...2.......7.3..9....5..8..21...1...5...

Yes, I always wondered how you knew of that one, but not the others.

Regards,
Blue.

In my old solver, I look for exocets with a wide scope.
In the new one, I did not reproduce that search so far and the search is limited to a 2 cells in a mini row base and a target in the band.

For the new entries in the data base, i only run the new solver, but I did not erase the known entry

that's it

regards

champagne

by **champagne** » Sat Jun 01, 2013 7:56 am

Another list of puzzles (in the green area as the previous one)
These are a more familiar kind of JE, but with 3 digits
I have an equivalent list with 4 digits, but containing 40201 puzzles

Hidden Text: Show

by **champagne** » Sat Jun 01, 2013 8:01 am

now in the grey area, the lot of oddities

Hidden Text: Show

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