On the left the base sets are rows 1, 2, and 9. Boxes can also be called blocks or regions. The Sudoku Assistant uses several techniques to solve a Sudoku puzzle: cross-hatch scanning, row/column range checking, subset elimination, grid analysis,and what I'm calling 3D Medusa analysis, including bent naked subsets, almost-locked set analysis. This is a place to learn and discuss sudoku puzzles. we have: The table above could also be called a forbidding matrix. Make sure you’re happy with why X-Wings work before moving on to Swordfish! You will be able to finish the puzzle quickly now. What is the swordfish technique in Sudoku? Consider the following Sudoku puzzle: At this point, after performing candidate reduction using other techniques, we have a swordfish in the 1s. the puzzle) is a partially completed grid.A grid has 9 rows, 9 columns and 9 boxes, each having 9 cells (81 total). The Sudoku Swordfish strategy is a basic advanced technique applied in the hardest levels of these puzzles to eliminate candidates. These guys are very hard to find. CRME is well suited to be a computer algorithm, but not a fast human way to solve Sudoku. On the left the base sets are rows 1, 2, and 9. Following on from my previous post on advanced Sudoku tips and tricks, in which I introduced the X wing strategy.This post is an introduction to an even more difficult method. Candidates 2 in r7c1 and in r6c8 are cover candidates that are not base candidates and can be eliminated. Sudoku Swordfish is a powerful technique used to solve some very hard Sudoku puzzles. But with this puzzle, I got as far as my techniques could go before I’d have had to break down and just start looking for weak/strong links, which doesn’t feel like strategy any longer, just brute force. Swordfish is another advanced technique which can eliminate certain candidates from squares. Solve the naked single and the logjam is broken. Sudoku rules A Swordfish is a 3 by 3 nine-cell pattern where a candidate is found on three different rows (or three columns) and they line up in the opposite direction. In the example, a proper Sudoku) has one solution. The cell (R8,C6) doesn't even have a 1. Swordfishes work exactly the same way as X-Wings, just with three base and three cover sets instead of only two. You won’t need a Sudoku strategy involving the swordfish technique when just learning how to play Sudoku – not every puzzle has a swordfish pattern – but as you progress, you may run into this technically challenging puzzle pattern – … As a member you get heaps of benefits. To prove this technique, I prefer to use induction. A Finned Swordfish is a pattern that is one cell short of being a swordfish - in other words, three columns that contain a candidate in only three rows, except for one, and vice versa. Consider the partial Sudoku below with the candidate 4 in the following cells. A Sudoku (i.e. One of the most advanced sudoku solving techniques explained on an example. I mean, what process do you use to look for swordfish in a diagram - … In this case two cells (R1,C9) and (R9,C1) are already solved. It is analogous to an Ntuple, which crosses the possible locations within a large container of N candidates with N cells. Most of the time you will have a mixture of two, three or four candidates lined up. At this point we do not know which three cells the 1 will reside in. The cover sets are columns 1, 5, and 8, the fish digit is 2. Article by DJAPE - ALL THING PUZZLES AND AWESOME COLORING BOOKS. ... does this count as a swordfish!? In this example, the swordfish is missing 5's at c6,d4. The yellow high lighted cells show the X-Wing formation. The complexity here is that you're using knowledge from 3 rows at the same time - and that's what makes them harder to spot. The New Sudoku Players' Forum. After you have tried all the easier strategies and find no new squares to solve (single possibility, only square, excluded hidden twins, naked twins, excluded subgroup), it may be worth looking out for Swordfishes. A Finned Swordfish is a pattern that is one cell short of being a swordfish - in other words, three columns that contain a candidate in only three rows, except for one, and vice versa. Consider the following Sudoku puzzle: At this point, after performing candidate reduction using other techniques, we have a swordfish in the 1s. if you wish to try to solve this puzzle yourself. Requirements to apply the Sudoku X-Wing strategy. Swordfish works the same way as X-Wing, but with 3 base sets instead of just 2. Using the ‘Swordfish’ Sudoku solving technique Step After you have tried all the easier strategies and find no new squares to solve ( single possibility , only square , excluded hidden twins , naked twins , excluded subgroup ), it may be worth looking out for Swordfishes . Swordfish A Swordfish occurs when in three rows all possible cells for a given digit lie in three columns. The three columns are 1, 6, and 9. If three rows have a candidate in up to three cells that lie on the same three columns, then the candidate can be eliminated from all other cells in the those columns. The analogy can be extended further. Swordfish. Sudoku has also been linked to declines in the potential for dementia to progress and has helped patients with mental health issues regain some normal daily function abilities. Even if you know it’s there, it can take some time to find. forbid any other combination. Sudoku Swordfish Solving Technique explained. X-Wing This is a technique slightly the opposite of what you just read about. A Swordfish pattern occurs when three rows (or three columns) each contain 2 or 3 cells that hold a matching locked candidate. Swordfish is similar to X-Wing, but instead of using a rectangle of four squares, it uses a grid of up to nine squares.You can use the swordfish strategy to eliminate candidates. “A Swordfish pattern occurs when three rows (or three columns) each contain two or three cells that hold a matching locked candidate,” according … This technique merely crosses the possible locations of a candidate in N rows with N columns. A Sudoku X-Wing pattern occurs in many of the more difficult Sudoku puzzles. Return from Sudoku Swordfish to Sudoku. The marked cells are the only cells in columns one, four and six that can contain a 1, and because each of those columns must only contain one 1, and since the cells also share three common rows, the cells are linked in a similar manner to the X-wings. cells form the swordfish. Congratulations on solving a very difficult Sudoku puzzle. Swordfish A Swordfish occurs when in three rows all possible cells for a given digit lie in three columns. Here is a minimal spread of a particular candidate X - a 2-2-2-2 formation. free Sudoku With N=4, we have a jellyfish. "Solve Sudoku" Introduction to Swordfish. We are looking for three rows (or columns) that contain up to three of a particular number in the same relative position. In row 1 the cells are (R1,C1), (R1,C6), and (R1,C9). 6 is the fish digit and rows R1, R6 and R9 are the base sets. google_ad_client="pub-6653090074968899";google_ad_slot="0747506666";google_ad_width=336;google_ad_height=280; You will need to know this technique in order to solve the occasional Sudoku puzzle that has this pattern without (ugh!) Credit for the matrix idea belongs to Andrei Zelevinsky and Bruno Greco (gb). I understand what swordfish are and why the work. Read my article Therefore it is safe to eliminate the 1s from all three columns (or rows) except for the six highlighted positions. For more difficult puzzles see my collection of printable. Since we’re dealing with 3 cells and 3 rows, there’s no forced box-like pattern like a 2 X 2 pattern forces. should be noted, however, that my presentation of the idea of forbidding matrices X-Wing example 2 : Load Example or : From the Start In this second example I've chosen a Sudoku puzzle where an enormous number of candidates can be removed using two X-Wings. In most cases, the technique might seem like much work for very little pay, but some puzzles can only be solved with it. When to Use Swordfish. When you removed the 1s, you now expose a naked single 3 in (R3,C9). Together with the Swordfish, the Sudoku-X-Wing technique is also a valuable strategy for any player to learn as it branches out into more complex patterns and techniques that are required to solve impossible puzzles. Take a look at the following Sudoku puzzle. The scanning technique is fast and usually sufficient to solve easy puzzles all the way to the end. Swordfish is a little trickier to spot than X-Wing for 2 reasons; firstly is the simple fact that the pattern is larger, with more cells involved. lacks their strict mathematical precision. In row 9 the cells are (R9,C1), (R9,C6) and (R9,C9). The easiest way starting a Sudoku puzzle is to scan rows and columns within each triple-box area, eliminating numbers or squares and finding situations where only a single number can fit into a single square. Swordfish is a generalization of X-Wing. The objective is to fill each empty cell with a number (1-9) that doesn't exist in its row, column, or minigrid. Post the puzzle or solving technique that's causing you trouble and someone will help. Boxes can also be called blocks or regions. Take a look at the following Sudoku puzzle. The logic behind this technique is that if the fin is not true, the rest of the Swordfish is. Next we move onto Swordfish, a technique in the same vein as X-Wing, only this time we’re looking at 3 columns and 3 rows, instead of X-Wing’s 2. You won’t need a Sudoku strategy involving the swordfish technique when just learning how to play Sudoku – not every puzzle has a swordfish pattern – but as you progress, you may run into this technically challenging puzzle pattern – and it may confound you. Swordfish. Using the ‘Swordfish’ Sudoku solving technique Step. type of such a matrix. Before diving into the Swordfish technique, make sure you fully understand the X Wing Technique as the Swordfish builds on that. In this … This is similar to Naked subset, but it affects the cells holding the candidates. What is the swordfish technique in Sudoku? Swordfish Swordfish works the same way as X-Wing, but with 3 base sets instead of just 2. As with the X wing there are 2 variations to this Swordfish strategy – the row and column variation. 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Thing puzzles and AWESOME COLORING BOOKS the following Sudoku puzzle: Swordfish works the same relative position a! The pattern as shown in the example shown, a Sudoku X-Wing pattern to the end to eliminate the,. This pattern will often break the logjam and lead you to the involves. Have this pattern AFFILIATE DISCLOSURE POLICY R1, C1 ), and 9 rows 1, 5 and!