The New Sudoku Players' Forum

[Leren]

I noticed that domp has raised some questions about Exocet Identification in the Minlex Routine thread. Rather than hijacking that thread I thought I'd try and provide some help here.

I haven't looked at Exocets much in a long time but here does anyway. Here is the puzzle.

Code: Select all

........1..2..3.4..4..5.6.......2.7.....8.4.5..347...6.3...7.9.2.98.....7.....1.

.

Code: Select all

*------------------------------------------------------------------*
| 35689     56789   5678   | 2679  2469  4689 | 235789 2358  1     |
|T1568-9    156789  2      | 1679  169   3    | 5789   4     789   |  S
| 1389      4       178    | 1279  5     189  | 6      238   23789 |
|--------------------------+------------------+--------------------|
|T14568+4-9 15689  T1568+4 | 13569 1369  2    | 389    7     389   |  S
| 169       12679   167    | 1369  8     169  | 4      123   5     |
| 1589      12589   3      | 4     7     159  | 289    128   6     |
|--------------------------+------------------+--------------------|
| 14568     3       14568  | 1256  1246  7    | 258    9     248   |  S
| 2        B156     9      | 8     1346  1456 | 357    356   347   |
| 7        B568     4568   | 23569 23469 4569 | 1      23568 2348  |
*------------------------------------------------------------------*
                             156   16           58           8

My solver says that there is one of two possible Exocets at this point, r8c2 r9c2 r2c1 r4c1 1568 or r8c2 r9c2 r2c1 r4c3 1568. The one that is ultimately True will be the one that does not contain 4, which occurs twice in Row 4, in the alternative 2nd Target cells r4c1 or r4c3. Nevertheless both possible 2nd target cells are limited to 1568-4, so you can eliminate other digits from them, and also make mirror node eliminations relating to the first Target cell, which is common to both alternatives. The S cells are clearly satisfied for both options since each base digit can be covered in the S cells by two vertical lines.

The Exocet that ultimately proves True is r8c2 r9c2 r2c1 r4c1 1568 and r4c3 is 4. OK I'll stop there and see what response I get.

Leren

[domp]

Thanks Leren for your answer.

I have done my (small) own solver.
I just recently add the exocet function.
At this moment, the routine is added after the solved solution, to check if I well understand the properties of an exocet.
I use two web solver, to compare my result : Andrew Stuart at sudokuwoki.org, and Philsolver at philsfolly.net.au.
For the puzzle ........1..2..3.4..4..5.6.......2.7.....8.4.5..347...6.3...7.9.2.98.....7.....1.. , both say : there is no exocet.
I try to use also, the 14 document of David Bird.
I is quite difficult for me, at this moment.

At this time my solver, with this puzzle :
-doesn't get target2 r4c1 because same column than target1 r2c1, so I keep only T2 r4c3
-doesn't see or analyse both '4' r4c13, (which need to set r4c3 = 4)
-count instances, for each base candidates and each Scell, and check each result to be between 1 or 2.
-eliminate within both target the non-base candidate.
This puzzle seems to be a bit difficult for me, a beginner with exocet.

-I just begin to check if each companion node doesn't contain one or more base candidates.
With this puzzle, the target2 companion contains base candidates and must not eliminate !?


Maybe the 2 last puzzles I have send, are easier to understand.
........1..2..3.4..4..5.6.......2.7.....8.4.5..347...6.3...7.9.2.98.....7.....1. (1224 nothing)
.....1..2....3..45..6...7...5..2..1..6...5..38..7..5...7.8..9..6.8.9....9.5..4... (2239 nothing)
for both I find valide companions, but I have a good, and a right eliminations, within targets.

Probably you will see, all my corrupted analysis and conclusions.

dom

[Leren]

Hi domp, as you were the target for this thread, thanks for replying.

As far as the first puzzle is concerned, there is an Exocet. Andrew Stuart and Phil Beeby both miss this case. In David P bird's Compendium AFAIK he appears to describe it as a JE+ in document 1 and gives a worked example in document no 6. He appears to describe the non-base digit as simply a locked (ie exactly 2 in the row or column) between the two Q cells and/or the R cells in the potential patterns. There does not seem to be any further terminology for this digit, so the use of the term "placeholder" in the other thread seems be as good as anything else. It's a pity that David did not see the need to give this some terminology, so that we could all be on the same page, for this quite common occurrence.

........1..2..3.4..4..5.6.....7..4...1..8...69....185...3..2....8.....6.7.19..... (1224 nothing) 2.3.7.9 base c9r46 target r3c8 r8c7
.....1..2....3..45..6...7...5..2..1..6...5..38..7..5...7.8..9..6.8.9....9.5..4... (2239 nothing) 1.2.3.4 base c2r89 target r3c1 r6c3

Code: Select all

*-----------------------------------------------------------------*
 | 3568  35679 56789 | 2468   24679 46789 | 23579   23789  1      |
 | 1568  5679  2     | 168    1679  3     | 579     4      5789   |
S|*138   4     789   | 128    5     789   | 6      t23789  23789  |
 |-------------------+--------------------+-----------------------|
 | 23568 2356  568   | 7      2369  569   | 4       1239  B239    |
S|*2345  1     457   |*2345   8     459   | 2379    2379   6      |
 | 9     2367  467   | 2346   2346  1     | 8       5     B237    |
 |-------------------+--------------------+-----------------------|
 | 456   569   3     | 14568  1467  2     | 1579    1789   45789  |
S| 245   8     459   |*1345  *1347  457   |T123579  6      234579 |
 | 7     256   1     | 9      346   4568  | 235     238    23458  |
 *----------------------------------------------------------------*

To make a long story short, my solver did not find the Exocet you described in the first puzzle.

Here is the short answer. It looks to me that digit 3 fails the line covering test. Ie you can't cover all the 3's in the S cells (marked with *) with exactly 2 lines.

If you don't know what I mean by this, go to David's files and read up on the line covering section.

The good news is that I've provided a list below of some Exocets. The list includes the puzzle and the location of the Exocet

Hidden Text: Show

Code: Select all

98.7.....7.....6....6.5.....4...5.3...79..5......2...1..85..9......1...4.....3.2.;1;GP;champagne dry;1;r3c1 r3c2 r2c4 r1c7 1234;;
.......39.....1..5..3.5.8....8.9...6.7...2...1..4.......9.8..5..2....6..4..7.....;3;tax;Golden-Nugget;1;r1c7 r2c7 r4c8 r7c9 1247;;
.2.4...8.....8...68....71..2..5...9..95.......4..3.........1..7..28...4.....6.3..;4;elev;3;1;r5c1 r6c1 r1c3 r8c2 1367;;
..3..6.8....1..2......7...4..9..8.6..3..4...1.7.2.....3....5.....5...6..98.....5.;6;elev;2;1;r8c1 r8c2 r9c6 r7c8 1247;;
1.......9..67...2..8....4......75.3...5..2....6.3......9....8..6...4...1..25...6.;7;elev;15;1;r6c5 r6c6 r4c3 r5c8 1489;;
1....6.8....7..1........5.6..9.4.....7.2...3.8....76..3....1..5.4.9.......2.7....;8;elev;16;1;r2c8 r3c8 r6c9 r7c7 2479;;
.2...67..4...8......93........9..57..1...7..2......61.3...4..6...8.......6...5.2.;9;tarekdb;tarx0075;1;r4c9 r6c9 r1c8 r9c7 3489;;
98.7.....6...5......4..93..5......6..7..8......9..24....1.....4....9.1.......1.32;11;GP;H1;1;r8c8 r8c9 r9c3 r7c6 5678;;
...4...89..7..92......3...526...1.....19.....7.....1..5...9..4...6..29.....8....3;15;elev;17;1;r5c1 r5c2 r6c6 r4c7 3458;;
........94....92......7..45..1.3.....7.6..9..8....7..2.3.7..8....6.1....9....5.2.;16;elev;18;1;r1c7 r3c7 r6c8 r9c9 1367;;
...4...8...7..92......3...526...1.....19......7....1..5......4..1.8....3..6..29..;19;elev;9;1;r5c1 r5c2 r6c6 r4c7 3458;;
.....6.8....1..2...9..7...5..5.4...734...8...97.........9...6..7...3...4...2...1.;30;elev;5;1;r5c3 r6c3 r3c1 r8c2 1268;;
..3..6.8....1......9..7...4...8..6..3...4...2.....5.1...2.9...37........94....5..;33;elev;6;1;r8c3 r9c3 r3c1 r5c2 1568;;
.2.4..7...5...9.3.6...7......5..8.9.7...2.....4.6..3.......1..85......1...1...9.3;34;elev;8;1;r8c7 r8c9 r7c3 r9c6 2467;;
98.7.....6.....9....5....7..4..3..2...85..4.......4..1..69..5......2...3.....1.4.;35;GP;H4;1;r3c1 r3c2 r2c4 r1c7 1234;;
98.7.....76....9....5......4...6..3...75..6.......2..1..86..5......1...2.....3.4.;36;GP;H5;1;r3c1 r3c2 r2c4 r1c7 1234;;
1...5...9..7...2...69..3.4....8........91..7.9....5..83..5....1..2...6...4.......;37;elev;34;1;r4c6 r5c6 r1c4 r7c5 2467;;
98.7.....6.....7....7.5....5....4.3...89..5......2..1..3.....4...98..6......1...2;44;GP;H7;1;r3c1 r3c2 r2c4 r1c7 1234;;
..3..6.8.4..7......9..3.....3.....15..5..18.........6.3..9..2...7..4......2..5..1;48;elev;L3;1;r4c7 r6c7 r1c9 r9c8 3479;;
...4.67....67.9.......1......9.6.4..5......2..8......33......5...4.9.1...1...2..8;53;elev;H2;1;r3c4 r3c6 r1c3 r2c7 2358;;
..1...5...2.4...6.3....7....6.28........9..2.......4.65.....1...9.8...4...7.....3;54;col;H2;1;r6c5 r6c6 r5c2 r4c8 1357;;
...4....9....8.2..6....3.1..1...7...7..6..5...3.....7.3....5.2...29..8......2...4;56;elev;32;1;r5c2 r5c3 r6c6 r4c8 2489;;
1...56.....71.......9....1..4..6.3.......8..29..7...6......24..5..6...9.....3...8;59;elev;33;1;r1c2 r1c3 r3c4 r2c8 2348;;
....56.8..5.7....3..8......2.....9...4.5....7....92.6.3.4.....15..1..4...1.....7.;61;elev;31;1;r9c1 r9c3 r7c4 r8c9 2689;;

Well, I'll stop there. You have penty of work and studying to do, but if you ask a question, I'll try and answer it as best I can.

Leren

[domp]

Hi Leren,
Thanks for your answer.

The short attached file, describes what my own solver try to do, and the mistakes with exocet.
Can you confirm, you can load it.
(I have "upload attachment", then "add a file", but I don't known if it's the right process.)


I want to prepare a short list of puzzles, with checking realised, and error abtained. Is it a good idea.

Maybe I can try to describe what I understand about the 4 mirrors cell of J2 exocet. Let me know.

dom

[Leren]

Hi domp, there is no attached file, due to a limitation of the forum. I suggest the best way forward for you is to read the first few chapters of the J Exocet compendium, which you will find here.

You don't have to read the whole thread, just the latest versions of the documents on the first page. Leren

<edit> OK, here is an example of a mirror node in action. The puzzle is ....56.8..5.7....3..8......2.....9...4.5....7....92.6.3.4.....15..1..4...1.....7. from my list above.

Code: Select all

*--------------------------------------------------------------------------------*
| 1479    2379    12379    | 2349    5       6        | 127     8       249      | < 29
| 1469    5       1269     | 7       1248    1489     | 126     1249    3        |
| 14679   23679   8        | 2349    1234    1349     | 12567   12459   24569    | < 269
|--------------------------+--------------------------+--------------------------|
| 2       368     1356     | 3468    134678  13478    | 9       1345    458      | < 68
| 1689    4       1369     | 5       1368    138      | 1238    123     7        |
| 178     378     1357     | 348     9       2        | 1358    6       458      | <  8
|--------------------------+--------------------------+--------------------------|
| 3       26789   4        |T29-68   2678    5789     | 2568    259     1        |
| 5       26789   2679     | 1       23678   3789     | 4       29-3   T2689     |
|B689     1      B269      | 234689  23468   34589    | 23568   7       25689    |
*--------------------------------------------------------------------------------*
                  S3         S1                                         S2
Exocet 1: r9c1 r9c3 r7c4 r8c9 2689 ; r8c8==r7c4 ; Eliminate non-common candidates.

The mirror node of the first Target cell r7c4 is the two cells next to the second Target cell r8c9 and these are r8c78. Since one of these cells, namely r8c7 holds a non-base cell, then whatever ends up in r7c4 must also end up in r8c8.

Does this help ? Leren

[domp]

hi Leren,

I find that : for exocet J2, the 2 companions are ALWAYS clues or solved, and for exocet J4, the 4 companions (2 are in the same cell) are ALWAYS clues or solved.

Maybe it's a hasard, but my solver has tested a file with around 50000 exocets...

Can you confirm. Otherwise, maybe you have some exemplars.

Domp

[domp]

Hi Leren,
I have to precise that my solver (at this moment), looks for, just 4 digits, and just column, exocets.
When it will be always correct, I will write the overall code.

Within your list, my solver well find the 9 exocets, 4 digits, and column.

Thanks for your help.
dom

[Leren]

Here is part of an old list where double exocets were found

Hidden Text: Show

Code: Select all

1......8...71....6.9.....5...56....7..17.4..5......34.57.2.............2..2.61...;226;elev;91;r7c5 r7c6 r8c3 r9c9 3489;r9c1 r9c2 r8c4 r7c9 3489
.23.....94.....1...9..3..4.2..81...4.....78..9...4...23...9...1.6..........5.....;264;elev;266;r1c7 r1c8 r3c1 r2c5 5678;r2c2 r2c3 r1c5 r3c9 5678
..3..6...45.7.....7...3..4.2................8..46...7......19....75...3...53...61;274;elev;273;r1c1 r1c2 r3c4 r2c8 1289;r2c5 r2c6 r3c3 r1c8 1289
...4..7......89.3..8..3...4.7.3...4.6....5....359...7.........1.4.8...9...2......;340;elev;223;r1c5 r1c6 r2c2 r3c8 1256;r2c7 r2c9 r1c2 r3c4 1256
....8..5..1.....3...23..7....45...7.9.....2.......64...9..1.....8..6......54....7;407;col;H15;r1c7 r2c7 r4c9 r9c8 1689;r5c8 r6c8 r3c9 r9c7 1689
1.....7....71.9...68..7......1.9.6.....3...2..4......3..8.6.1..5......4......2..5;422;elev;247;r2c1 r2c2 r1c5 r3c7 2345;r3c4 r3c6 r1c3 r2c7 2345
1...5......7..9....8.3...4.....7.3...3.2....4..5..362...8..1..2.6.8..4..9.......8;425;elev;251;r7c7 r9c7 r3c9 r5c8 1579;r4c9 r6c9 r3c7 r8c8 1579
......7....71.9...68..7......1.9.6.....3...2..4......3..8.6.1..5......4..1...2..5;512;elev;136;r2c1 r2c2 r1c5 r3c7 2345;r3c4 r3c6 r1c3 r2c7 2345
12...67....7....63....7.........8.9..4.5.......1.2.3..5....4......9....8..2.6.1..;1198;elev;853;r1c8 r1c9 r3c3 r2c5 4589;r2c1 r2c2 r1c5 r3c7 4589
98.7.......7.65.........7..7...4..3..2......1..95..6..1......2...59..8.......3..4;1208;GP;H284;r1c5 r1c6 r3c3 r2c7 1234;r2c1 r2c2 r3c4 r1c7 1234
1..4....9.5...9.2...8...6.....39..7..7............75.2.3...2.9.6.......8..4.1....;1523;elev;637;r4c7 r4c9 r6c2 r5c6 1468;r6c4 r6c5 r4c2 r5c8 1468
....3.7.5.8.4...9.5.........2..48..........2.6.92...........1...6.9...4...1..7..3;1663;col;H104;r4c1 r4c3 r5c4 r6c8 1357;r6c5 r6c6 r5c2 r4c8 1357
......7..4....9.3..8....5.42..39.....45..2..........2.5....3.4.......6.19...64.5.;1692;elev;306;r4c2 r4c3 r6c6 r5c8 1678;r5c4 r5c5 r6c1 r4c8 1678
12....7....7....36....7.........4.9...6.2.1..5..8.....6..9....4.8...5.....1.6.3..;1740;elev;653;r1c8 r1c9 r3c3 r2c5 4589;r2c1 r2c2 r1c5 r3c7 4589
.23.....94.....1....9.2..4.2...9...1.....58....56........8...7..6...7...9...4...3;1759;elev;1737;r1c7 r1c8 r3c1 r2c5 5678;r2c2 r2c3 r1c5 r3c9 5678
98.7.....7...6.8....6..5...4......3...89..7......2...1.3......4..76..5.......1.2.;1771;GP;H355;r1c5 r1c6 r2c3 r3c7 1234;r3c1 r3c2 r2c4 r1c7 1234
.2..5....4.6..9..2..9...6.....5....1.9...25......3..2....8...7..4...59...6...42..;1921;elev;1797;r1c1 r1c3 r3c6 r2c7 1378;r2c4 r2c5 r3c2 r1c7 1378
..3.....9.5.1..2.......7..5..4..165..1.5....2.....81..3....4.....8.7.....9.6...2.;2459;elev;1626;r1c7 r3c7 r5c8 r9c9 3478;r4c9 r6c9 r2c8 r9c7 3478
....5..8....7.9..2..92...5..1....3..6....4.....8.7...53......1...2.9...7.4.6..5..;2480;elev;1611;r1c4 r1c6 r2c3 r3c9 1346;r2c7 r2c8 r1c3 r3c5 1346
.2....7..4....9.3.6..723.4...85.........1....9....4.6..94....5.5.....6.3.....5...;2502;elev;1659;r7c7 r7c9 r9c1 r8c6 1278;r8c2 r8c3 r7c6 r9c8 1278
.....6..9..6.8.1..7..2...5..4...1..83..5...7.....4.....72....9....9.....9.....3.5;2515;elev;H77;r7c7 r7c9 r8c1 r9c4 1468;r9c2 r9c3 r7c4 r8c8 1468
1....6..9.5.....3..8....4..2...6...7...2..3....87.......1.9.5..7..6....1.4..1..6.;2535;elev;1698;r7c4 r9c4 r1c5 r4c6 3458;r5c5 r6c5 r1c4 r8c6 3458
1..4...8..5...9..2..9...6......41.6....6..8.36.........72...5..8..3...1.....7....;2548;elev;H81;r4c7 r4c9 r5c1 r6c4 2579;r5c5 r5c6 r4c1 r6c8 2579
1..4......5...9.2...8...6.....39..7..7....9.......75.2.3...2.9.6.......8..4.1.2..;2549;elev;1720;r4c7 r4c9 r6c2 r5c6 1468;r6c4 r6c5 r4c2 r5c8 1468
1..4...8..5...9..6....3.1...9...5..7..8.2.4.........2.7.5..3....3.69............3;2582;elev;1716;r7c4 r7c5 r9c2 r8c9 1248;r8c1 r8c3 r9c6 r7c9 1248
1.....7....71.9...68..7......1.9.8...4.2....5.......2...8.6.9..5....3.4.........3;2584;elev;1694;r2c1 r2c2 r1c5 r3c7 2345;r3c4 r3c6 r1c3 r2c7 2345
1...5......7..9....8.3...4.....7.3...3.2....4..5..36....8..1..2.6.8..4..9......68;2585;elev;1709;r7c7 r9c7 r3c9 r5c8 1579;r4c9 r6c9 r3c7 r8c8 1579
..34...8.4..7......89.3......5...6.....2....18...9..4.3...4..7......12...6......5;2609;elev;1648;r2c2 r2c3 r1c5 r3c8 1256;r3c4 r3c6 r1c1 r2c8 1256
12....7....7....63....7..1..4.5..........8.9...6.1.3...7.9....85....4.....2.3.6..;2626;elev;1728;r1c8 r1c9 r3c3 r2c5 4589;r2c1 r2c2 r1c5 r3c7 4589
98.7.....6.....7....7.65...4......32..86..9......3.....2.....41..98..5.......1...;2643;GP;H590;r1c5 r1c6 r2c3 r3c7 1234;r3c1 r3c2 r2c4 r1c7 1234
1...5......7..9.3...9..754...4..3.7..6........9.8........79..2......24.3..2......;2673;elev;975;r7c7 r7c9 r8c3 r9c6 1568;r8c4 r8c5 r7c3 r9c8 1568
.2..5....4.67.....7....2..6....9......1.......4.6....53.....8...6.2....4.7.5...32;2691;elev;1269;r1c1 r1c3 r3c4 r2c9 1389;r2c5 r2c6 r3c2 r1c9 1389
.2..5.78....7..........3..42...7.59..95........7...3....2.9.87.8..6.....9.......1;2699;elev;1255;r5c1 r6c1 r1c3 r7c2 1346;r8c3 r9c3 r1c1 r4c2 1346
.2......9..67...2..8..3........1.9.......3..46..2...5..6.8...7.8.5.....1..7.4....;2707;elev;1205;r8c2 r9c2 r2c1 r6c3 1349;r1c3 r3c3 r6c2 r7c1 1349
.2..56...4..7.....7....2..6....9......1.......4.6....53.....8...6.2....4.7.5...32;2709;elev;1265;r1c1 r1c3 r3c4 r2c9 1389;r2c5 r2c6 r3c2 r1c9 1389
.2..5...94....9......2..64.2..6....4..8....7.9..5....6.1..2....6..9....2......3..;2715;elev;1251;r1c7 r1c8 r3c1 r2c4 1378;r3c5 r3c6 r1c1 r2c9 1378
.2......94.....13...9.3..4.2...9...4..78..........78..3...4...1.64..5......6...5.;2735;elev;1210;r1c7 r1c8 r3c1 r2c5 5678;r2c2 r2c3 r1c5 r3c9 5678
.2......94.....13...9.3..4.2...9...4..78..........78..3...4...1.6...5......6..45.;2736;elev;1209;r1c7 r1c8 r3c1 r2c5 5678;r2c2 r2c3 r1c5 r3c9 5678
.2.....8...718...6..97....1........5..5.71...96.5......9....4.......3.....69....7;2737;elev;1213;r5c1 r5c2 r4c4 r6c9 2348;r6c5 r6c6 r4c3 r5c9 2348
.23....8.4.7.8...3.......4.2..6....7.....5..68.6.7..3....9......1.......7.4.6.3..;2751;elev;1303;r4c8 r5c8 r2c7 r9c9 1259;r1c9 r3c9 r6c7 r9c8 1259
...45.........92.........14.98..3...3..24......4...3...4.....768....24..9..7..8..;2776;elev;1092;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
...45.........92.........14.98..3.4.3..2.......4...3...4.....768....2...9..7.48..;2777;elev;1091;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
...45.........92.........14.98..3.4.3..24......4...3...4.....768....2...9..7..8..;2778;elev;1090;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
..3.567..4..7.........3..6...43...5...56.847.........1......9..8...2......75...4.;2786;elev;1166;r1c1 r1c2 r3c4 r2c8 1289;r2c5 r2c6 r3c3 r1c8 1289
....5....4....92.........14.98..3.4.3..2.......4...3...4.....768....2...9..7.48..;2858;elev;1046;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
....5....4....92.........14.98..3...3..24......4...3.........768....24..9..7.48..;2859;elev;1047;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
....5....4....92.........14.98..3.4.3..2.......4...3.........768....24..9..7.48..;2860;elev;1044;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
....5....4....92.........14.98..3.4.3..24..........3...4.....768....2...9..7..8..;2886;elev;1045;r4c4 r4c5 r6c1 r5c7 1567;r5c2 r5c3 r6c6 r4c7 1567
.....67...5.1.9.3.68.3...1..3.8...5.5.......2..4......3.59......9..18..........9.;2894;elev;1018;r7c5 r7c6 r9c2 r8c8 2467;r8c1 r8c3 r9c4 r7c8 2467
...4..7.......9.3..8....5.42..39.....45..2..........2.5....3.4...4...6.19...6..5.;2901;elev;1068;r4c2 r4c3 r6c6 r5c8 1678;r5c4 r5c5 r6c1 r4c8 1678

Here is a PM from my solution for the second puzzle in the list.

Code: Select all

*--------------------------------------------------------------------------------*
| 1       2       3        | 467     5678    4568     |B567    B5678    9        |
| 4       578     5678     |M679-2  T5678   M5689-2   | 1       235678  35678    |
|T5678    9       5678     | 1267    3       12568    | 2567    4       5678     |
|--------------------------+--------------------------+--------------------------|
| 2       357     567      | 8       1       3569     | 35679   35679   4        |
| 56      1345    1456     | 2369    256     7        | 8       13569   356      |
| 9       13578   15678    | 36      4       356      | 3567    13567   2        |
|--------------------------+--------------------------+--------------------------|
| 3       4578    24578    | 2467    9       2468     | 24567   25678   1        |
| 578     6       1245789  | 12347   278     12348    | 234579  235789  3578     |
| 78      1478    124789   | 5       2678    123468   | 234679  236789  3678     |
*--------------------------------------------------------------------------------*

Exocet 1: r1c7 r1c8 r3c1 r2c5 5678 ; Eliminate cands in r2c4 & r2c6 that are not in r3c1 and are not SIS cand 9.

Note that the mirror node non base solution cell for target cell r2c5 is not known, but it must be either one of r2c46, because there are only two 9's in Row 2. As it turns out the two eliminations in those cells are crucial, and make the detection of the second Exocet unnecessary. The puzzle solves with basics from there.

wrt to your question re companion cells being clues or solved, that may be true for JE2's, I can't say for sure, but if you put this in your code you will not find the JE+ pattern, shown in my first post. JE+'s and JE++'s are quite common so you will have to make a choice as to whether you want to write separate code for the various patterns, or one piece of code for all possible patterns.

Leren

[ghfick]

For:
........1..2..3.4..4..5.6.......2.7.....8.4.5..347...6.3...7.9.2.98.....7.....1..

YZF_Sudoku finds the following:

Junior Exocet:Base Cells-r8c2,r9c2;Target Cells-r2c1,r2c3,r4c1,r4c3;Cross Cells-r247c456789
Target Cells Check: r2c1<>9,r4c1<>9
Mirror Check:r2c1<>58,r5c3<>7
JE Version POM Test:r2c1<>5,r2c1<>8

The POM test is new for me. I am exploring this addition.

[Leren]

POM sounds like Pattern Overlay Method. In any event r2c1 <> 58 twice, firstly in the Mirror node check and secondly in the POM test.

Leren.

<Edit> Meanwhile I've had a look at this puzzle .9.....3.2..........3.1.9.7..6..........6.37....1.8..6..8.3...1..7.8...3...4...5. which you can find on Andrew Stuart's site here which is his example of a Double Exocet pattern.

Fair enough, but you don't actually need the double exocet.

Code: Select all

*----------------------------------------------------------------------------------*
| 145678  9        145      | 25678   245     24567    | 124568  3        2458     |
| 2       145678   145      | 356789  459     345679   | 14568   1468     458      |
| 4568    4568     3        | 2568    1       2456     | 9       2468     7        |
|---------------------------+--------------------------+---------------------------|
| 45789   24578    6        | 2359    2459    23459    | 1+245-8 1+249-8 T2459-8   |
| 14589   12458    12459    |B259     6      B2459     | 3       7        24589    |
| 3+459-7 3+245-7 T2459     | 1       7       8        | 245     249      6        |
|---------------------------+--------------------------+---------------------------|
| 4569    2456    8         | 25679   3       25679    | 2467    2469     1        |
| 14569   12456   7         | 2569    8       12569    | 246     2469     3        |
| 1369    1236    129       | 4       29      12679    | 2678    5        289      |
*----------------------------------------------------------------------------------*

Exocet 1: r5c4 r5c6 r6c3 r4c9 2459 => - 8 r4c9; - 8 r4c78, - 7 r6c12, lclste.

The point being that Mirror Cell eliminations in both cells are linked to the double Exocet pattern, in a way that I don't understand, but it's quite common for these to be all you need. Not always but quite common.

Leren

[ghfick]

There is a bug in YZF's code as those two exclusions are duplicated. The JE Version POM test looks like a Pattern Overlay and JE logic used together in a 'new' way?

[yzfwsf]

Hi Gordon, this is not a bug. I designed this intentionally to see what methods can be used to achieve the same elimination.

This kind of POM adds the consideration that the Base Cells and Target Cells are both true or false at same time.

[ghfick]

Hi YZF,
I should have known better.
Do you have some puzzle examples where JE Version POM test gives exclusions that are not seen by other JE steps?
Gordon

[Leren]

Junior Exocet:Base Cells-r8c2,r9c2;Target Cells-r2c1,r2c3,r4c1,r4c3;Cross Cells-r247c456789

Perhaps there is a bug here. This JE+ pattern can't have a target cell at r2c3, which is a clue 2 that is not in the base. A printout glitch maybe ?

Leren

[yzfwsf]

HI, Gordon!
Those cross-line eliminations are independently produced by JE POM!

Code: Select all

:0000:x:98.7..6..75...+6.9...6......4...3......56...8......4..2.1...23....95...7.....6...1:::
98.7..6..75.....9...6......4...3......56...8......43.2.1..2.9....98...7.........1
98.7..6..5...8..7...7..6...4..........8.5.9.......3.42.1......3..9.6.7.....2.1...
98.7..6..5...6......6....7..4......3..9.8.7.....2...1...5.9.8.....1....4.....3.2.
98.7..6..75.....9...6......4.....3....56...8.....43..2.1..2......98...5......9..1
:0000:x:98.7..6..75.....9...6......4...6...3..85...6.....4.2...2...1.....98...5.....3.1..:826 836::

Hi, Leren!
When outputting text, my code simply outputs the target pairs(TQ,TR) of JE structure without considering the actuation. Actual situations are indicated using cell coloring. Any way, thanks for the feedback.