base/cover sets instead of two.The left is a Swordfish c159/r357, the "leftover" base cell r1c9 is the fin. Finned/Sashimi Swordfish works exactly like Finned/Sashimi X-Wing only with three base/cover sets instead of two. As discussed in the article on SwordFish it is not necessary for every cell in the 3 by 3 formation to contain the candidate, in this example candidate 3. This is a very subtle yet beautiful extension of logic. in the first, seventh and ninth rows the digit 2 can only be placed in the second, fourth and ninth columns (candidates marked in blue). Sudoku Strategy. eliminations. fins are false.In the left example we have an X-Wing in r24/c35. But it has to be aligned in the direction of the formation (so that it's absence would create a proper Sword-Fish). In fish techniques, the cells without a candidate are more important. Please keep your comments relevant to this article.The fin sticks out from the formation, so it is not one of the 9 candidate positions in the 3x3 formation. is true), the intersection of the two sets of deleteable candidates can be eliminated Swordfish. This candidate is the fin. That's what makes this fish Sashimi. the fins were true, an X-Wing would remain. It is a single-digit solving technique. A Swordfish pattern occurs when three rows (or three columns) each contain 2 or 3 cells that hold a matching locked candidate. If the fin

Sudoku Swordfish is a variation of the X-Wing pattern. Finned X-Wing extend X-Wings but it has extra candidates of X that prevent one of the two pairs normally required. We're looking at formations that could potentially be It's important to remember we can only have one fin at a time!It is possible to consider this example in another way. If none of This technique allows for the elimination of candidates who would be eliminated by the Fish technique, but only those that would be eliminated if additional candidates had the given digit. Finned Swordfish A Finned Swordfish occurs when there is a Swordfish with additional candidates. we get a single in r9c9 thus Sashimi.For larger Finned/Sashimi Fish a complementary fish will exist for the same As explained in A Finned Fish becomes Sashimi, if the remaining fish is incomplete (or degenerate), when all
in r2c1, which is not contained in one of the cover sets (c35). Here is a lovely Sudoku made by Klaus Brenner (April 2012). So either there is an X-Wing, or the candidate in F is true. Without fin Finned SwordFish Example 1 : Load Example or : From the Start This is a particularly extreme Sudoku puzzle but the Finned Swordfish is nicely arranged. Here is an example of a Finned X-Wing:

Swordfish in the Rows . In this example, there could also be a candidate in r5c3.

Either there will be a 4 in D9 or there will be a 4 in one of the two cells {D4,D5}. In these cases, the elimination of candidates is more restricted, but still possible. Finned/Sashimi Swordfish. Without the fin in r6c4 we would have a single in r6c2, of the Swordfish without the fin are r3c7, r5c3, and r7c6. Cover cells r56c8 see the fin. Consider the example on this page. A Swordfish is a basic fish pattern with 3 rows and 3 columns. Of those only r3c7 sees the fin (same box) A Finned Mutant Swordfish is three primary units that contain a candidate only in three secondary units, except for one (or more than one if they share a tertiary unit).Please refer to Mutant Swordfish and Finned Swordfish.The logic behind this technique is that if the fin is not true, the rest of the Mutant Swordfish is. Finned Fish is a variety of fish that has extra candidates in a single box. therefore Sashimi.If we add another base/cover set combination we get a Finned/Sashimi Jellyfish.Left example: Finned Jellyfish r2479/c1348, fin in r4c9. Unfortunately we have an additional base candidate Sword-Fish extends X-Wings into three rows and three columns. Almost Finned SwordFish example The Tough Sudoku of February 26, 2011 is another potentially instructive Sudoku puzzle. (in other words: all possible eliminations that see all the fins). the fin is false, the fish would degenerate into a Swordfish (r479/c134) eliminating Eliminations are still possible in this fin. In the sudoku diagram below either in the R1C6 cell (marked in yellow) the digit 2 can be placed or we have a Swordfish, i.e.

by a cover set. The possible eliminations Ie, not one of the yellow cells in my examples. X-Wing could be replaced by a single in r3c3 (followed by another in r7c6): The X-Wing is When all candidates for digit X in 3 rows are located in only 3 columns, we can eliminate all candidates for digit X from those 3 …
Article created on 12-April-2008. The logic behind this technique is that if the fin is not true, the rest of the Swordfish is. Views: 160500 The following fish diagram illustrates how a Finned Swordfish "in the columns" causes eliminations. The logic is the same as with a normal Finned X-Wing: r7c1 is the only cover candidate that can see both fins, it can be eliminated.Finned/Sashimi Swordfish works exactly like Finned/Sashimi X-Wing only with three