How to Solve Sudoku Puzzles : Nishio Strategy in Sudoku

[fr3d420]

Hello good sir... If I may nit pick you for a moment, ... at the end of your videos... you say... "In my next clip..." but your clips are not numbered or linked to in a fashion that would indicate order... do you see what I'm saying? anyway... you should link to the next video in your video info. or number them.

[kichoman]

Steve: You're pronouncing a couple Japanese words incorrectly. Japanese vowels, when transliterated into English using the Latin alphabet follow consistent rules. The u takes an "oo" as in "pool" sound and o takes a strong "oh" as in "pole." Therefore, the do in "suDOku" sounds like the word for female deer. The second problem is the word Nishio. The letters io cannot form the sound "oo." For Japanese words, i is always pronounce "ee" as in "see" and the o is still "oh" as in "pole."

[MonSwon]

What the hell is wrong with ppl. This is one stratergy to figure out what numbers to put in the boxes. He hasnt made it up, its a known stratergy. He is just illustrating it. It isnt too hard to grasp whats being said.

[MonSwon]

good tip cheers, may use that in future if I get stuck.

[BlakeVII]

I what is the difference between this technique and the forcing chains technique?

[Evessal]

@BlakeVII The key difference between forcing chains and nishio is that in forcing chains, you pick a cell with two candidates and see if it forces another cell into an answer. Say R1C1 has candidates 2 and 7, you pick 2 and it forces cell R3C3 to become a 9. You go back and choose 7, and you end up with the same result, that R3C3 is forced to become a 9. You now know with certainty that cell R3C3 is a 9 and can fill it in.

[Evessal]

@BlakeVII In Nishio, as the video mentions, you take a guess and hope it completes the puzzle for you. If not you have to go back and try again. Forcing chains gives you a logical method to find solutions. Nishio is frowned upon by the serious Sudoku players and should only be used as a last resort. And if it does have to be used, then whoever designed the puzzle did a poor job.

[BlakeVII]

@Evessal Your last statement - If the Nishio method has to be used then the puzzle is a poorly designed one(?) Is that not another way of saying that a suduko puzzle should never be designed to be THAT hard?

To me, thats kind of like doing away with difficulty to avoid unfairness and frustration.

The above is no way a criticism of what you wrote, I just want to know your view.

Please reply so that I can know your answers.

[Evessal]

@BlakeVII Well, what is Nishio? A method where you pick an unknown cell with no more than two candidates, hypothesize that one of the guesses is your correct answer, and see what happens. Hopefully in a few moves a contradiction occurs, telling you that your initial guess was wrong. If your guess manages to force some other cells without contradictions, then maybe you guessed right, or maybe not. You won't know until you get further in the puzzle.

[Evessal]

@BlakeVII So where am I going with this? Simply the fact that Nishio is taking a guess and hoping you guessed right. And that's where the controversy sets in. Sudoku is a puzzle where you should be using logical methods to eliminate candidates and eventually solve the puzzle. Nishio is trial and error, not logic. You can guess on any puzzle and hope it leads you to the right answer. The logical process, if you use it correctly, will ensure that you do get the right answer.

[BlakeVII]

@Evessal I agree with the fact that NEVER should guessing be the last resort of solving a sudoku puzzle and believe me I've come across puzzles that would make you go out and hit the first old age pensioner in sight... only kidding!

Thanks for your reply.

[Evessal]

@BlakeVII In the end, it has nothing to do with puzzle difficulty, you can create enough diabolical puzzles that take hours and maybe even days to solve requiring very advanced logical methods, but if you have to resort to guessing? Bad design. And that, Blake, is not only my qualms against the Nishio method, but why it is a very controversial method and one which many Sudoku experts frown upon. Many Sudoku strategy books will not even deign to mention it.

[chaddvanzanten]

Heh heh. I already knew this strategy, but I didn't have an evocative Japanese word for it. I just called it guessing.

[pinktiger3]

@chaddvanzanten hahahaha, I was going to put something like that. I don't see any difference between this being a strategy or guessing, hahaha

[ron7006]

Wait... I appreciate this technique, but didn't you watch it before posting? You blatantly put the two fives in the same column. Re-watch between thirty and forty seconds.

[topshonuff]

This guy is a waste of time.. I don't see he's method of being useful or quicker.. This video looks like for a college class presentation.. It's short, quick and doesn't make sense..

[allinrizzo]

Sounds like cheating to me, expert village sucks

[RoC1909]

Uh.....the ONLY way to cheat at Sudoku is by looking at the answers. Please tell me, what is YOUR definition of cheating at Sudoku?

[jamesfirst92]

its cos ur fucking stupid

[misskity6]

i don't agree with the guessing method. you never have to guess! either 2 boxes definitely have to be 2 numbers. or in worst cases, 3 boxes have to be 3 numbers to help narrow it down. but nishio is a cop-out method if you're lazy. watch my vid about how i do a hard sudoku. i explain it easily. =)

[jamesnazgul]

I wouldn't say nishio is just a guessing technique. You need to choose a good starting point and build a series of implications from a given assumption. So you are using logic and discovering a set of constraints that could possibly disallow a number in a given square. So to me you're not guessing, you're analyzing the constraints related to a possible number in a square.  In fact building implications from an assumption to reach a contradiction is a valid proof technique in logic/science.

[jamesnazgul]

Btw, misskitty, I did run across a couple of your sudoku videos and from just the brief parts I watched of them they are much better than anything expertvillage has ever put out on youtube on any subject. Not sure where these guys came from but they are no experts that's for sure. I watched a video they did on craps also and they truly have no clue what they're talking about.

[misskity6]

well thanks. i actually watched this vid after i made mine (to check out the "competition") and i do think mine are easier to understand than some out there. thanks for noticing. honestly, i made a vid because i when i did puzzles i would say "wow if someone knew that it would really help."

[NightPrince7]

actually you do need the nishio method in some sudoku puzzles. its not guessing - you choose a box with 2 possible numbers for example, and run them through as if they were definite - one will logically not be able to be so (unless the puzzle has multiple solutions) - this is still logic.

[kasuomiyake]

your tips are great but this particular video seams to have a video setting problem. It is taking too long to download. Please check it. It does not happen with your other videos.

Thks