## Bi-directional cycle + Unique Rectangle Typ 2

Advanced methods and approaches for solving Sudoku puzzles
hobiwan wrote:
aran wrote:I have noticed before that you come up with bases that have overlapping truths eg here r4 and b4 does not necessarily have two truths.
Question : is this a good idea ?

Take the following grid for example:
Code: Select all
`.----------------------.-------------------.-----------------.|  12369   4     12369 | 8     29    7     | -23    5    169 ||  7      *1239  5     | 134   6     349   |  8    #24   19  ||  12369   8     12369 | 1345  2459  23459 | -234   7    169 |:----------------------+-------------------+-----------------:|  1245    125   124   | 7     3     8     |  6     9   *245 ||  8       39    39    | 2     45    6     |  7     1    45  || *2456   *256   7     | 9     1     45    | @245   8    3   |:----------------------+-------------------+-----------------:|  23456   7     2346  | 3456  2459  23459 |  1     24   8   || *2469    69    8     | 46    7     1     | *245   3   *245 ||  12345   1235  1234  | 345   8     2345  |  9     6    7   |'----------------------'-------------------'-----------------'Finned Franken Jellyfish: 2 r268b6 c1279 fr2c8 efr6c7 => r13c7<>2`

Without the overlap r6b6 you need a Squirmbag

Hobiwan, that's fine, I see know where you are coming from with endo-fins (and exo-fins). Nice idea, after all
aran

Posts: 334
Joined: 02 March 2007

hobiwan wrote:I realize of course that fishes that size [squirmbag] are of practically no use for a manual solver.

Although one doesn't come across them all that frequently, I have no trouble finding them as long as I am using a sudoku frontend (ie. something like Simple Sudoku) that allows you to highlight & individually color candidate cells/squares. (Finding them with pen & paper only would be more difficult but IMO still possible.) Incidentally, sirdave & I are in communication with an author of one of the popular Itouch/Iphone sudoku apps to provide coloring of candidate cells/squares ala SS just for this reason- finding complex patterns such as ALS Chains & big fish. Surprisingly, of more than 80 sudoku apps, none provide this feature. Hopefully, more later.
DonM
2013 Supporter

Posts: 475
Joined: 13 January 2008

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