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2020-06-04T03:57:45Z

Created page with "A '''Finned Swordfish''' is the finned version of a Swordfish. It is a single-digit solving technique. The formal definition for a Finned Swordfis..."

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A '''Finned Swordfish''' is the [[Finned Fish|finned]] version of a [[Swordfish]]. It is a [[single-digit]] [[solving technique]].

The formal definition for a Finned Swordfish "in the rows" is:
: When 3 rows only have candidates for digit '''X''' in 3 columns and a single box that intersects with at least one of these 3 columns, then we can eliminate all candidates for digit '''X''' inside that box, which are located on one of these 3 columns, but not on one of the 3 rows.

Swap the words "rows" and "columns" in this definition for a Finned Swordfish "in the columns".

== How it works ==

The following [[Project:Fish diagram|fish diagram]] illustrates how a Finned Swordfish "in the columns" causes [[elimination]]s.

[[Image:Finned_swordfish.png]]

Like the basic [[Swordfish]], you do not need a [[candidate]] in each [[cell]] marked '''X'''. In [[fish]] [[technique]]s, the cells without a candidate are more important.

== Example ==

The following example shows a Finned Swordfish "in the columns" for the digit 7 is shown in yellow in the grid, with a [[fin]] located at '''r6c7'''.

[[Image:FinnedSwordfish.png]]

This Finned Swordfish leads to the [[elimination]] of 7 from '''r4c9''', which is shown in blue. For clarity, the [[Project:Fish diagram|fish diagram]] for this example is shown below.

X . . | . . X | X . .
/ . . | . . / | / . .
/ . . | . . / | / . .
------+-------+------
X . . | . . X | X * *
X . . | . . X | X * *
/ . . | . . / | F . .
------+-------+------
/ . . | . . / | / . .
/ . . | . . / | / . .
/ . . | . . / | / . .

An argument for the elimination of 7 from '''r4c9''' is by cases on the fin at '''r6c7'''. Case 1 - the fin has value 7: then nothing else in box 6 can have value 7. Case 2 - the fin has value <>7: then the remaining yellow cells form a [[Swordfish#Swordfish_in_the_Columns|swordfish-in-columns]] and so nothing else in rows 1, 4 or 5 can have value 7. Result: common to both of these cases are the deductions that none of r4c8, '''r4c9''', r5c8 or r5c9 can have value 7.

== See also ==

* [[Fish]]
* [[Swordfish]]
* [[Finned Fish]]
* [[Finned X-Wing]]
* [[Finned Jellyfish]]
* [[Sashimi Swordfish]]

Finned Swordfish - Revision history

Rooted: Created page with "A '''Finned Swordfish''' is the finned version of a Swordfish. It is a single-digit solving technique. The formal definition for a Finned Swordfis..."