## Can You Solve This Without Trial and Error?

For fans of Kakuro

### Re: Can You Solve This Without Trial and Error?

Another sum I enjoyed solving was H51722. Somehow, though I didn't have to resort to Trial and Error at all, there were ample opportunities to lose one's way with a mistake. A lot of deduction was to be gone through to get to the solution eventually. I just got it past.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

Authority wrote:as soon as I finish a kakuro I never want to see it again!

I feel that way a lot, but sometimes I like to go back over them to see if I can learn something that will make it easier to solve puzzles in the future.
saul

Posts: 105
Joined: 01 February 2013
Location: Kansas City

### Re: Can You Solve This Without Trial and Error?

Just solved H31101. Must admit with two things to help, one was Trial and Error and the other was a bit of luck. Because, I had made an assumption at one point, like D1 or D2 (D for direction). And let's say I chose D1, within that, I had to choose D11 or D12 and I picked up one and yet I landed the right solution without having to repeat an alternative track. Meaning, I had a 25% chance of reaching the right solution but landed there right in the beginning. May be 33% for the first choice D1 had a 66% probability of being true.

Hope some of you may like to try this puzzle, it was nagging indeed.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

Hi Everyone,

This is Mani wishing you all a Happy New Year 2014!

As a new year challenge, take up sum H61041, I just solved it after elaborate crunching.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

Mani wrote: .... I had made an assumption at one point, like D1 or D2 (D for direction). And let's say I chose D1, within that, I had to choose D11 or D12 and I picked up one and yet I landed the right solution without having to repeat an alternative track. ....

-- Which means you found a solution without meeting what many of us feel is an obligation, namely, to establish uniqueness. Hmm.

Of course, if I were in a Kakuvo-solving tournament, I'd do the same thing.

Bill Smythe
Smythe Dakota

Posts: 564
Joined: 11 February 2006

### Re: Can You Solve This Without Trial and Error?

Smythe Dakota wrote:
Mani wrote: .... I had made an assumption at one point, like D1 or D2 (D for direction). And let's say I chose D1, within that, I had to choose D11 or D12 and I picked up one and yet I landed the right solution without having to repeat an alternative track. ....

-- Which means you found a solution without meeting what many of us feel is an obligation, namely, to establish uniqueness. Hmm.

As you know Bill, I agree with you, but to each his own.

Mani, I have a question for you. Suppose D1 had worked out badly. Could you have gotten back to the point at which you chose D1, after trying D11, and D12? As far as I can tell you can save only one version of the puzzle in the atk web app, so if you attempt a "multi-level T&E" and your first guess is wrong, there's no easy way to get back to the point at which you made it.

Yesterday, I was working a medium when I got stuck and resorted to T&E. In one cell my candidates were 2 and 6, and when I tried the 2, it turned out to be the correct guess. As Bill would have done, I went back to my saved version, and tried to show that the 6 was wrong, but I quickly got stuck and I thought another level of T&E would be necessary. I didn't know how to deal with this problem. Fortunately, I eventually saw that I had missed an inference that made even the first level of T&E unnecessary.

One thing that I don't like about the atk interface is that when you solve the puzzle, the saved version is erased, so in a case like this, you have to be careful not to fill in the last cell, if you want to go back and establish uniqueness.
saul

Posts: 105
Joined: 01 February 2013
Location: Kansas City

### Re: Can You Solve This Without Trial and Error?

saul wrote:Mani, I have a question for you. Suppose D1 had worked out badly. Could you have gotten back to the point at which you chose D1, after trying D11, and D12? As far as I can tell you can save only one version of the puzzle in the atk web app, so if you attempt a "multi-level T&E" and your first guess is wrong, there's no easy way to get back to the point at which you made it.

This is why I am not fond of kakuros that require T&E to solve, especially when the interface does not allow it easily. But this makes me a hypocrite because some of the hard-rated daily puzzles on my site seem to need T&E, and the interface isn't conducive to allowing it. Of course, the definition of T&E can vary from person to person, and I'm not even sure that any ATK puzzles actually require it (someone could probably prove me wrong on this one). On bigger/harder puzzles there are lots of things to consider and it's easy to make a mistake with candidates or overlook a relatively simple deduction.
Authority

Posts: 11
Joined: 09 December 2013

### Re: Can You Solve This Without Trial and Error?

Nice observations Saul and Authority!

As regards the first one, i.e. not being able to save more than one version, well, obviously in the case I described, I can only save the status before taking the D1 route and would have to come back there to try a D12 then a D21 and D22, if it were that I am the least lucky.

I agree with Authority's remarks and it is much like Chess wizards going deep down in their analysis to 10/15 moves ahead. It is a trade-off decision to make, whether to crunch that long in the mind or save a version and get on to Trial-Error, though the purist would never like Trial and Error.

Struggling with two more sums now and will share once I get to the end of one at least.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

It would be nice if Kakuro sites would allow you to "bookmark this position as A", "bookmark this position as B", etc (more than one) and then "revert to A", "revert to B", etc.

You should also be able to bookmark, and retrieve, the final position.

Bill Smythe
Smythe Dakota

Posts: 564
Joined: 11 February 2006

### Re: Can You Solve This Without Trial and Error?

Bookmarking multiple positions and saving them in the user's hard disk is a good idea.

I just cracked one of the 2 toughies I was at for a while. Try H64411. It is nice providing many challenges along the way to try every technique that one has in one's armoury.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

Mani wrote:Bookmarking multiple positions and saving them in the user's hard disk is a good idea.

But how do you do that with atk?
saul

Posts: 105
Joined: 01 February 2013
Location: Kansas City

### Re: Can You Solve This Without Trial and Error?

Saul,
I should have been clearer I suppose. It is one of the suggestions passed on to ATK for consideration. If I were ATK though, my tendency would be not to accept it for it simplifies the solving process!
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

ATK's H54322 needs a serious try. Really tough one, just got past it after quite some struggle.
Mani

Posts: 33
Joined: 13 December 2013

### Re: Can You Solve This Without Trial and Error?

Mani wrote:I just cracked one of the 2 toughies I was at for a while. Try H64411. It is nice providing many challenges along the way to try every technique that one has in one's armoury.

Arrrgh. I misread this as H6441, and I've been banging my head against it. I can't even do it with T&E. Here's how far I've gotten:
H6441.png (87.14 KiB) Viewed 638 times

Can anyone give me a hint as to how to proceed?
saul

Posts: 105
Joined: 01 February 2013
Location: Kansas City

### Re: Can You Solve This Without Trial and Error?

Authority wrote:This is why I am not fond of kakuros that require T&E to solve, especially when the interface does not allow it easily. But this makes me a hypocrite because some of the hard-rated daily puzzles on my site seem to need T&E, and the interface isn't conducive to allowing it.

I read this post too quickly the first time. When you say "my site" does that mean you have a kakuro site? If so, please tell us where it is.
saul

Posts: 105
Joined: 01 February 2013
Location: Kansas City

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