Twin Equivalent Sudokus

For fans of Killer Sudoku, Samurai Sudoku and other variants

Postby hutman » Mon Dec 04, 2006 2:17 pm

Shintaro, I appreciate the tremendous amount of time and effort spent by your friend in explaining his stuff. However, I find the explanation look rather like a teacher giving a mathematics lesson to a class.

It is rather long-winded and boring. Most people like me had experienced a hard time struggling with mathematics in schools. So we don't like to see your friend's stuff attract jokers and half-baked Fermats trying to show off the power of their supercomputers. We want puzzles, not mathematics that are churned out by supercomputers.

So for goodness sake, tell your friend to stop posting any more of his stuff on this forum:!:
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Postby Pyrrhon » Mon Dec 04, 2006 3:29 pm

Dear Hutman,

its interesting to hear that you hate mathematics. But the mathematics of a puzzle are as well interesting to me as to make handcrafted puzzles or to solve them with my hands. Please don't conclude from your own interests to the interests of all participitiants in this forum. Many sudoku solving techniques came into the world because some guys looking from a mathematical point of view or from a computer science point of view to sudoku have found the techniques.

I also think that the equivalence variant that is discussed here is not a good idea. But the flaw is not that a guy that is interested in mathematics has developed this variants (Henry Kwok has devloped more interesting sudoku variants). The flaw is that he has taken a equivalence class that makes it arbitray to find the puzzle solution. Henry Kwok and his aliases seem to feel that, so they have changed the rules frequently. Other equivalence classes could be better, for example the class Kwok used in his other invention, called twin corresponding sudoku. Also the restriction to changes of chutes was a better idea. But all this was made clear by the discussion here. And so the discussion was fruitful even because the puzzles were not so good.

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Postby udosuk » Tue Dec 05, 2006 2:14 am

Just want to say, it's a pity we don't have a moderator anymore...:(

From what I see, Shintaro's "step-by-step explanation of the solution" is not logically sound, and thus not considered "convincing" by many entities here who have participated in the discussion...

Now I'm really interested, how many aliases (friends:?: ) does Mr. Henry Kwok have...:)
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Postby Shintaro » Tue Dec 05, 2006 12:04 pm

Pyrrhon wrote:
...(Henry Kwok has devloped more interesting sudoku variants)...Other equivalence classes could be better, for example the class Kwok used in his other invention, called twin corresponding sudoku. Also the restriction to changes of chutes was a better idea. But all this was made clear by the discussion here. And so the discussion was fruitful even because the puzzles were not so good.


Pyrrhon, my friend is glad at least to hear a few nice words from you. Just using an analogy about the farce here, a person had posted a puzzle which consisted of a group of 3 coins on each side with the instruction that the solver had to interchange the position of each group of coins by moving a coin towards the other group and letting another coin from the other group jump over it.

Some jokers came along and raised a farce by bringing in some university mathematics and posted a puzzle with 1000 coins on each side and made it into a problem of interchanging the position of 1000 coins.

My friend has never declared or boasted that he has discovered any super mathematical theorem, otherwise he would have announced it at a top university or at a mathematical society gathering. He is adapting a well-known mathematical concept to make a very simple puzzle that is solvable even by students. The puzzle just consists of at most two simple transformations with plenty of clues available unlike those that consist of over 70,000 permutations that need "machine solutions". It is analogous to the simple puzzle with 3 coins on each side, not 1000 coins.

udosuk wrote:
From what I see, Shintaro's "step-by-step explanation of the solution" is not logically sound, and thus not considered "convincing" by many entities here who have participated in the discussion...Now I'm really interested, how many aliases (friends ) does Mr. Henry Kwok have...


Now the ball is in the court of udosuk and other armchair critics to "improve" on the method of solving or offer an alternative method, otherwise they are simply NATO's. In my friend's country, there is a popular term known as "NATO" which means "No action, talk only". It is a term reserved for armchair critics who just criticise but unable to offer any alternative solution.

So far the method has just been dismissed as "guessing", "not logically sound" and "unconvincing" with nobody providing any good explanation, refutation or alternative. None has yet to refute the method by contradiction.

His method is analogous to that used by police making whatever available at the scene of a crime. Imagine a detective had entered a room (analogous to the sudoku grid) where he found a number of objects (analogous to the digits) at the scene of a crime.

He found lipstick, a high-heel shoe and a lady's handkerchief (analogous to the 3 six's in the middle of the puzzle). The first idea that comes to anybody's mind is naturally that the criminal was a female. Anybody would come to this conclusion and uses the object as clues for his detection until he discovers a contradiction halfway. The method is natural and logical as there are no other ways for the detective. So don't just dismiss it as illogical or unconvincing, otherwise the detective simply made no headway.

Here I have to repeat and emphasize it again. My friend has never declared that he has invented or discovered any super theorem. This variant is made so simple with one or two transformations that even some students can solve it. So what is the farce of bringing in all the mathematical stuff fit for university academics?

If anybody considers his solution as rickety as an old cart, then he should try to invent the car or at least a better cart, not just criticise. If he can't make a car, he has either to walk or just ride on the old rickety cart.

udosuk, my friend is waiting for you at http://www.sudoku.org.uk/discus/messages/1289/1289.html?1165183777.

There you can ask him any question to your heart's content. It looks like he feels very lonely there, without any business or anyone to keep him company!:D
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Postby RW » Tue Dec 05, 2006 1:05 pm

Shintaro wrote:The puzzle just consists of at most two simple transformations with plenty of clues available unlike those that consist of over 70,000 permutations that need "machine solutions".

Shintaro, you really don't have a clue what your talking about, do you? The twins created by your friend have 5327 and 20113 solutions, which in practise makes them no different from gsf's puzzles in this sence.

You say the puzzle is very simple, solvable by students, yet you failed to show us a satisfying solution.

You say that we just use terms like "guessing" and "not logically sound" without explanation, read my last post and there's all the explanation you need.

You're talking about "armchair critics" and "NATO"... As far as I can see I'm the only one so far in this thread to come up with a logical method that don't require T&E, you're the one with lots of talk and fancy analogies but no input of value yet regarding how to solve these puzzles. To say "guess" or "follow your hunch that..." does not count as valuable input.

You keep repeating that it's simple because you only need two permutations. This was Never mentioned in the rules, so you can not use it in your solution, how hard is this to understand?

Seriously, I don't have a problem with the puzzles, only with the claim that they are better than other puzzles as they would be easier to solve. Your solution isn't a real solution, now stop trying to cover it up by saying that "the ball is in the court of other people" to find better solutions. You are the one who said that there is a simple solution, the ball is in your court until you either provide a simple valid solution or admit that you were wrong.

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Postby Shintaro » Tue Dec 05, 2006 5:37 pm

RW wrote:
... As far as I can see I'm the only one so far in this thread to come up with a logical method that don't require T&E...the ball is in your court until you either provide a simple valid solution or admit that you were wrong.


Yes, you have solved his first and second puzzle with flying colours. You have scored distinctions for your methods in solving both puzzles. The first and second puzzle involve interchanging entire blocks of columns (rows) only. The is no controversy over the methods in solving the first two puzzles.

However, there is huge hullabaloo over my friend's method in solving the 3rd puzzle which involves interchanging of rows (columns) within the same block of rows (columns) only. This variant is more complicated than the one involving the first two puzzles. The whole issue is no longer a puzzle but a mathematical issue for university professors. The contest (without tangible prize but eternal fame) is now open to everyone to find the "correct" method to solve the 3rd puzzle.

My friend admits his solution is as rickety as an old cart, so now can you or anyone else show the "correct" method to solve his 3rd puzzle? He presents you or anyone else with two options: either to show the "correct" method to solve his 3rd puzzle or to demonstrate how to solve gsf's "pseudo puzzles" without using machines.

He is waiting eagerly for the news of your earth-shaking breakthrough. He is waiting to applause for you wholeheartedly. He is praying that he won't be calling you an an armchair critic or NATO in the next message.:D
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Postby tarek » Tue Dec 05, 2006 5:57 pm

Shintaro wrote:udosuk, my friend is waiting for you at http://www.sudoku.org.uk/discus/messages/very_lonely_and_cold_place.html?1165183777.

There you can ask him any question to your heart's content. It looks like he feels very lonely there, without any business or anyone to keep him company!


Shintaro wrote:However, there is huge hullabaloo over my friend's method in solving the 3rd puzzle which involves interchanging of rows (columns) within the same block of rows (columns) only. This variant is more complicated than the one involving the first two puzzles. The whole issue is no longer a puzzle but a mathematical issue for university professors. The contest (without tangible prize but eternal fame) is now open to everyone to find the "correct" method to solve the 3rd puzzle.

I think that the joker is quite evident ......

give it a couple of days everybody without posting here & no one would even remember this.....

Somebody apparantly is thriving on attention here ..... so sad:(

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Postby Shintaro » Wed Dec 06, 2006 12:10 am

Pyrrhon wrote:
...Other equivalence classes could be better, for example the class Kwok used in his other invention, called twin corresponding sudoku.

Agreed. That monster was the first to be tamed for puzzle solving under the name of "Twin Corresponding Sudokus".

Pyrrhon wrote:
Also the restriction to changes of chutes was a better idea.

Agreed. That monster can still be tamed for puzzle solving under the name of "Twin Equivalent Sudokus".

Pyrrhon wrote:
I also think that the equivalence variant that is discussed here is not a good idea...The flaw is that he has taken a equivalence class that makes it arbitray to find the puzzle solution.

Agreed. That monster is still the "wild wolf" of equivalent puzzles.

RW wrote:
The twins created by your friend have 5327 and 20113 solutions, which in practise makes them no different from gsf's puzzles in this sence.

If anybody can make a wild guess and still get a single correct solution out of 20113 solutions, he can easily become rich without working. He just spends his time in a casino and keeps guessing every day.

This so-called "guessing" method, however, is not applicable to all puzzles. Anybody is welcome to find an alternative method or try to refute or contradict this method for the 3rd puzzle here. It is only applicable to this puzzle that has been painstakingly planned and designed for easy puzzle solving. It is just like a wild wolf that has been caught and chained in a cage.

How to tame the "wild wolf" of equivalent puzzles is a challenge to mathematicians. It would be a waste of time for puzzle solvers to search for it as it is doubtful if any standard "correct" method could ever be found. In the process, they may even lose more hours of sleep.

tarek wrote:
Somebody apparantly is thriving on attention here ..... so sad

My friend has been submitting puzzles quietly to several well-known and established websites for almost a year. He is helping a government agency in his country to promote sudoku to students. Hence he has no need for your attention or anybody else's attention, otherwise he won't wait quietly by himself in a corner of a website without getting any "business".:)
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Postby udosuk » Wed Dec 06, 2006 4:08 am

Shintaro wrote:Some jokers came along and raised a farce by bringing in some university mathematics and posted a puzzle with 1000 coins on each side and made it into a problem of interchanging the position of 1000 coins.


Shintaro on Sun Nov 26, 2006 3:10 pm wrote:Here is another example by Henry Kwok for tarek, RW and anybody who is interested in his variant. Have fun!:D

Twin A
Twin B

So who's the first "joker" who "came along and raised a farce"? This puzzle is the very first one posted in this thread which is still not solved by logic (despite the so-called "step by step solution" which turned out to be just a bunch of guessing practice)...

Shintaro wrote:... armchair critics, NATO's...

I've spent time trying to solve your puzzle (refer to the link above) but couldn't do it using logic... So what am I supposed to do more for "actions"? So I decided to stop wasting any more precious time on it and do other more important stuffs instead...

I was just merely stating my observation, that you haven't posted a solution that convinces our viewers here that it's sound logic, or prove that your puzzle has a unique solution... And I said it based on the general response from this page and the previous pages... I'm not criticising you or anything, just stating the obvious truth (based on the replies here, not what I think myself)...

And it's funny you keep asking us to post a better solution... From what I read here all entities other than yourself (gsf, Pat, Pyrrhon, ronk, RW, tarek and even hutman) think that there is no possible logical solution for your puzzle, so there exists no such thing as "a better solution"... Not even a "solution" in the strict sense (with logical steps and without guessing/assumption)...

Shintaro wrote:My friend admits his solution is as rickety as an old cart, so now can you or anyone else show the "correct" method to solve his 3rd puzzle? He presents you or anyone else with two options: either to show the "correct" method to solve his 3rd puzzle or to demonstrate how to solve gsf's "pseudo puzzles" without using machines.

Both options are invalid here: there is no "correct" method to solve your 3rd puzzle (your method is certainly not), and there is no way to solve gsf's "puzzle" (it's a valid puzzle consisting of 2 "pseudo sudoku grids") without using machine... But gsf never said there is such a way, he was just posting a puzzle that is as unsolvable for human as your 3rd puzzle...

Shintaro wrote:udosuk, my friend is waiting for you at http://www.sudoku.org.uk/discus/messages/1289/1289.html?1165183777.

There you can ask him any question to your heart's content. It looks like he feels very lonely there, without any business or anyone to keep him company!:D

Thanks but no thanks... I have absolutely no interest to ask "your friend" any question... Why don't you tell your friend to come over? What's the difference between discussing here and there?

tarek wrote:Somebody apparantly is thriving on attention here ..... so sad:(

I'd say let somebody thrive for a while... But I'm prepared to leave it alone when you guys are ready...:)
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re(2): solving Puzzle Three

Postby Pat » Wed Dec 06, 2006 10:42 am

Shintaro wrote:the 3rd puzzle which involves interchanging of rows (columns) within the same block of rows (columns) only



when Puzzle Three was posted, there was no mention of a change-of-rules.

under the old rules ( swap digits, swap chutes, but keep lines within chute ) there was no answer;
hence the assumption that the new rules allowed all 3 swaps - digits, chutes, and lines within chute.

it now appears that the rules for Puzzle Three are - swap digits, swap lines within chute, but keep chutes.

knowing the rules of the puzzle,
it may be possible to devise a logical method of solving it--

~ Pat
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Postby Shintaro » Wed Dec 06, 2006 1:53 pm

After this forum discussion, my friend and I have learned a valuable lesson about the problems caused by the ambiguity of rules. My friend has told me that next time he would state all the rules clearly. He also intends to make his puzzles as simple as possible by providing more starters and reducing the number of permutations.

Sorry to you Pat, RW and all other forum participants for the inconvenience caused.:)
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Postby Shintaro » Wed Dec 06, 2006 3:04 pm

udosuk wrote:
This puzzle is the very first one posted in this thread which is still not solved by logic (despite the so-called "step by step solution" which turned out to be just a bunch of guessing practice)...

As I had pointed out, if it is a wild guess, my friend would become rich by spending all his time in a casino where he could keep guessing every day instead of wasting his time thinking how to churn out a new Sudoku variant. Unfortunately, he is neither a Merlin nor a wizard in Harry Potter's story.

Actually, he is using very simple techniques that look for similar boxes between the twins. In his opinion, it is very important for a puzzle maker to do whatever he can to make it easy for all the puzzle solvers to solve his puzzles, not to try whatever means to foil them or place obstacles to prevent them from finding the solution.

Hence he has devised the above simple techniques that are applicable for solving a small subset of equivalent puzzles which are artificially planned and devised in such a way that patterns can be easily observed. As I had said before, his intention is to ensure all solvers succeed in solving the puzzles, not to foil or frustrate them.

My friend has not discovered the universal or standard method to solve all equivalent puzzles that involve interchanging of rows (columns) within the same block of rows (columns). As I had said before, he called it the "wild wolf" of equivalent puzzles. He is still trying to tame the monster. However, I have told him frankly not to waste his time because I doubt he could ever succeed in doing so.

It seems strange to me that only gsf is able to see through my friend's techniques as shown below.

gsf wrote:
I constructed the puzzle to foil the techniques that look for similar boxes between the twins -- because the twins have identical patterns that work is already done -- and for this puzzle gets you nowhere
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Postby Scott H » Tue Jul 10, 2007 9:59 am

I found the first puzzle in this thread to be a pleasant by-hand solve (well, I used Simple Sudoku as a clerk). I think I basically observed what RW saw in his post on page 2. After solving each puzzle as far as it will go individually, there is enough infomation in the available digits to see that 9 in twin B must map to 3, 5, or 6 in twin A, and 5 in twin B must map to 3, 6, or 8 in twin A. This quickly finds blocks 31 and 32 in twin A map to blocks 31 and 33 in twin B (i.e., chutes 2 and 3 are swapped). This generates enough new substition info to progress and find bands 1 and 2 are also swapped.

Can anyone provide puzzles 2 and 3 from Shintaro's unnamed "friend"? (Hanry Kwok?) The posts in this thread that supposedly give the puzzles are dead links. Also, were the rules for the puzzles ever resolved? The lack of communicating the rules for each puzzle was rather unfortunate.

Thanks.
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puzzles 2 and 3

Postby Pat » Wed Jul 11, 2007 11:35 am

Scott H wrote:Can anyone provide puzzles 2 and 3 from Shintaro's unnamed "friend"? (Hanry Kwok?)
The posts in this thread that supposedly give the puzzles are dead links.




puzzle 2
posted by Henry Kwok (2006.Nov.24) —
broken link: www.SuDoku.Org.UK/discus/messages/1289/3102.html?1167399398#POST8019



puzzle 3 ( new rules )


A. [ 19 clues ]

Code: Select all
 7 . . | . . . | . . 8
 . . . | . . 5 | . . .
 . . . | . 6 . | . . 3
-------+-------+------
 . . . | . . . | 2 . .
 . . 3 | 6 . . | . . 1
 . . 2 | . 3 . | . . .
-------+-------+------
 2 . . | 5 . . | . . .
 . . 9 | . . 2 | 3 . .
 . 6 . | 8 . . | . . 9



B. [ 19 clues ]

Code: Select all
 . . 6 | . . . | . . 2
 . . . | . . . | . . .
 . . . | . 3 . | . 7 5
-------+-------+------
 . . . | . 5 . | . . .
 5 . . | 3 . . | 2 . 9
 . . . | . . 9 | . 4 .
-------+-------+------
 . . 4 | 1 . . | . . .
 . 3 . | . . . | . . 8
 8 9 . | . . 4 | . . .

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