127.0.0.1: Created page with "A '''Jellyfish''' is a fish with 4 rows and 4 columns. == Jellyfish in the Rows == : When all candidates for a particular digit in 4 rows are located in..."

2021-10-24T18:55:09Z

Created page with "A '''Jellyfish''' is a fish with 4 rows and 4 columns. == Jellyfish in the Rows == : When all candidates for a particular digit in 4 rows are located in..."

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A '''Jellyfish''' is a [[fish]] with 4 [[row]]s and 4 [[column]]s.

== Jellyfish in the Rows ==

: When all [[candidate]]s for a particular [[digit]] in 4 rows are located in only 4 columns, we can [[eliminate]] all candidates from those 4 columns which are not located on those 4 rows.

[[Image:jellyfish.png]]

=== Example ===

In a real Jellyfish, you will rarely see all 4 rows have 4 candidates for the selected digit. Each row can contain between 2 and 4 candidates.

[[Image:jellyfish-rcx.png]]

Jellyfish for digit 8 in rows 3,4,6,7 and columns 2,5,8,9.

== Jellyfish in the Columns ==

: When all [[candidate]]s for a particular [[digit]] in 4 columns are located in only 4 rows, we can [[eliminate]] all candidates from those 4 rows which are not located on those 4 columns.

=== Example ===

Because a Jellyfish in the columns often has a complementary Jellyfish in the rows, many computer solvers only report the Jellyfish in the rows. This example also has such a complement:

[[Image:jellyfish-crx.png]]

Jellyfish for digit '''3''' in columns 1,2,6,7 and rows 1,3,5,9

Complementary Jellyfish in rows 2,4,6,7 and columns 3,4,5,9

== Notes ==
Each of the defining [[line]]s can have 2, 3 or 4 candidates, but together they cover 4 of the crossing lines. Because there are many possible configurations for 2, 3 or 4 candidates in 4 lines, a Jellyfish is much harder to find than an [[X-Wing]] or [[Swordfish]]. See [[Fish and Subsets#Trawling for Fish Using Locked Sets|Trawling for Fish Using Locked Sets]] for a technique that makes Jellyfish easier to find.

Because a Jellyfish has 4 defining lines, there will always be 2 lines in a single chute. However, when the defining lines of a Jellyfish occupy only 2 chutes, the eliminations it causes immediately trigger a subsequent [[Locked Candidates]] move, like column 8 in this diagram.

[[Image:jellyfish lc.png]]

== See Also ==
* [[Fish]]
* [[X-Wing]]
* [[Swordfish]]
* [[Finned Jellyfish]]
* [[Sashimi Jellyfish]]
* [[Mutant Jellyfish]]

[[Category:Solving Techniques]]
[[Category:Single-Digit]]

Jellyfish - Revision history

127.0.0.1: Created page with "A '''Jellyfish''' is a fish with 4 rows and 4 columns. == Jellyfish in the Rows == : When all candidates for a particular digit in 4 rows are located in..."