This is the archive of the old posts from Djape .Net, more or less as they used to be. Please go to djape.net to see the new website.

Category Archives: Solving tips

Instructions on how to solve Sudoku and other puzzles. Detailed solving tips and techniques for various kinds of puzzles, including Sudoku variants.

Twin Nonets

Lets formalize the technique that can be used when solving overlapping puzzles, which I have been referring to as “the new solving technique” and that I now call Twin Nonets. Basically, this technique is a sub-technique (or if you like – a consequence) of the naked/hidden triplets technique that you are all probably aware of. […]
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X-Wing

UPDATE: I changed the image to reflect an actual X-Wing. As a matter of fact, this is the puzzle that I posted a couple of days ago under the “daily Sudoku” page. Here is a quick explanation for the “X-Wing” technique. Suppose you reach the following position and you can’t go any further: You look […]
Posted in Solving tips | Tagged , , , , , | 29 Responses

Swordfish

As promised, I implemented the Swordfish classic Sudoku solving technique in my Perfect Sudoku software and generated a few puzzles. I just posted one of them on the Daily Sudoku page. However, I ran my generator and generated a couple of thousands Killer Sudokus and NONE of them required Swordfish, just as I speculated before. […]
Also posted in Killer Sudoku | Tagged , , , , , , , , , , , | 8 Responses

Subtraction combo

Udosuk, one of our visitors who is most active in giving hints for the puzzles we post here, has made a suggestion for a new solving technique for Killer Puzzles. He calls it “subtraction combo”. I’m posting his explanation here (slightly modified): I’m proposing a trick which I think many players already knew, but I’ll […]
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You Asked For It!

As promised, I just posted a puzzle with the rating that is currently in the lead in our poll. And that, apparently, is INSANE. This puzzle requires all Killer techniques + it requires some advanced classic Sudoku techniques (match subsets etc). It does not require trial and error! I hope someone will solve it without […]
Also posted in Samurai sudoku | Tagged , , , , , , , , , , , | 12 Responses

Complex innies/outies – part two

I saw two comments (by Graham and David) for the puzzle posted on October 25, and I think there’s a little clarification on “complext innies/outies” that should be made here. You should look for innies/outies in more than just one row/column/nonet. This is a good example of such puzzle. See this image: Click on the […]
Fiendish Killer Sudoku Book

Also posted in Free sample puzzles, Killer Sudoku | Tagged , , , | 3 Responses

Complex innies/outies

One of our visitors (Phyllis) asked about the puzzle posted on October 13. Now, this puzzle definitely doesn’t need any trial and error to be solved – in fact it’s only rated as “thinker”. However, it requires a technique that in the new version of Perfect Sudoku will be called “complex innies/outies”. It is basically […]
Fiendish Killer Sudoku Book

Also posted in Free sample puzzles | Tagged , , , , , , , , , , | 3 Responses

Cage Splitting – Killer Sudoku

Ok, here is the explanation of the “Cage/fence splitting” solving technique for Killer Sudoku puzzles that I promised before. I will use the puzzle posted on Friday, October 7 and solve it step by step using this method. We extend the idea of the “innies” and “outies” solving technique, except that you’re not looking for […]
Also posted in Killer Sudoku | Tagged , , , , , , , , , , , , | 2 Responses

Two very cool puzzles today!

I’ve posted two very beautiful puzzles today. Killer Sudoku: This one might look very difficult but after a tough first step, the solution unfolds really easy. This is at least how I got the solution :), there could be a simpler one. Anyhow, I will use this one to explain the technique that I call […]
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Killer Sudoku – September 27th

Many people have asked about the Killer Sudoku posted on September 27th. I haven’t tried to solve this Killer by hand but it is very much possible that it requires either a lot of math (the technique that I call “cage/fence splitting”, which will be explained in the next few days) or that it cannot […]
Also posted in General, Killer Sudoku | Tagged , , , , | 12 Responses
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