Luke451 wrote:Now I have to wonder why I've never seen him suggest such a move in his solutions
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Up to now, I haven't been too keen on this approach...the idea of having to find a number of chains that all converge on a common conclusion seems somehow unattractive...That said I wouldn't hesitate to do so for a deadly pattern. And further we saw how effective 999 Springs approach was in Gee's example. So I may reconsider
As to Kraken : I think of it as a fin acting through a chain rather than directly on an elimination target. In that sense Kraken fin rather than Kraken fish would seem to me better terminology, but I think Kraken fish is orthodox.
In keeping with the "halieutic" context, the Kraken fin can be thought of as a tentacle and - tying in to Don's "Kraken column" term - maybe Kraken has developed to mean tentacular emanations from a common source such as a strong set, as in the case of those {999}.
To finish with a Kraken example (profiting from daj's excellent find of a two-finned Sashimi Franken Jellyfish)
- Code: Select all
Sashimi Franken Jellyfish r169b5\c2457 w/2x fin cells => [r4c2]<>9 -or-
Sashimi Franken Jellyfish r159b4\c2457 w/2x fin cells => [r6c7]<>9
*--------------------------------------------------------------------*
| 4 159 2 | 6 159 3 | 159 7 8 |
| 8 159 19 | 12459 7 1249 | 3 6 145 |
| 6 3 7 | 1459 8 149 | 2 49 145 |
|----------------------+----------------------+----------------------|
| 37 19 6 | 13459 13459 149 | 1579 8 2 |
| 37 2 8 | 1359 1359 6 | 1579 49 145 |
| 5 4 19 | 8 2 7 | 19 3 6 |
|----------------------+----------------------+----------------------|
| 9 6 45 | 1234 134 124 | 8 15 7 |
| 1 8 3 | 7 6 5 | 4 2 9 |
| 2 7 45 | 149 149 8 | 6 15 3 |
*--------------------------------------------------------------------*
we can also proceed as follows with respect to candidate 9 :
Base set units : rows 1,5,6,9
Cover set units : columns 2,4,6,7.
ie exactly four truths in the base, and exactly 4 in the cover.
When that is done, there are two members of the base set which remain uncovered : 9r6c3 and 9r5c8.
So those are fins.
Any candidate 9 in the cover sets and outside the base sets is a potential target.
Were there no fins, all such items would be eliminated.
Because of the fins, only those candidates seen by both fins are eliminated.
Take 9r4c2.
Lies in the cover column c2, lies outside base sets (not in rows 1,5,6,9)=>potential target.
Seen directly by fin 9r6c3.
Seen indirectly by fin 9r5c8 : 9r5c8-9r6c7=9r6c3-9r4c2. Which is therefore a Kraken fin.
So that creature is also a two-finned Sashimi Kraken jellyfish.
But it has lost its Franken status since there is no longer a box as one of the units covered or covering.
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