The New Sudoku Players' Forum

[Carcul]

Hi Bob.

The next "nice loop" for the configuration above can be a triple implication chain, with a trivalue tripod at r7c3, which implies r8c4=6. Alternatively, you can use the chain posted above by Rubylips.

As far as I am concern, this is not trial and error because it is involved in nice loop construction a process of patern recognition: this patern is the construction of strong and weak links between nodes, and make logic deductions whenever we have a loop. I think this is different from just try a number in a cell and see if there is a contradiction. But, if you prefer to see it just as T&E, then I can say that nice loops are a much more elegant form of trial and error. Why don't you try yourself, by hand, and try to find some loops in the exercises that I have posted above? I guess you will see the difference.

BTW, I have replied to a post of you in the progammers forum.

Regards, Carcul

[DadSierra]

i have been trying to follow ths discussion and work through some of the examples, however i need help with the vocabulary being used. can one of the active memboers point me to a post where some of these terms are defined?

after becoming profecient at moderately difficult puzzles, i jumped to the back of the book to (Will Shortz volume #2, puzzle 93) and have found myself seriously stuck. I am pretty sure i need to understand loops to solve this puzzle as I all of the cells remaining to be solved contain multiple potential solutions and a few of them have the same set of potential solutions..

any pointers or advice appreciated.

DadSierra

[sheila08]

after becoming profecient at moderately difficult puzzles, i jumped to the back of the book to (Will Shortz volume #2, puzzle 93) and have found myself seriously stuck. I am pretty sure i need to understand loops to solve this puzzle as I all of the cells remaining to be solved contain multiple potential solutions and a few of them have the same set of potential solutions..

any pointers or advice appreciated.

DadSierra

Please post your puzzle as haven't a clue what your puzzle looks like.
Also, there are a zillion places that point you to both Simes' and Angus' guides. Look around some!

By the way, the Will Shortz book I have (The Ultimate Sudoku Challenge) has puzzles that are harder than they are rated, and yet I am not convinced that there is only one solution to a puzzle. The only two "ultimate challenge" puzzles require an x-wing, but one has been forewarned...

Cheers, Sheila

[Carcul]

Hi DadSierra, and welcome to this forum.

Try this link , this one , this one , and this one . But if you have some doubts, post them in this forum.

Regards, Carcul

[Pep]

Pep,

Your candidate grid allows an elegant Two-Sector Disjoint Subsets elimination:

Many thanks rubylips for that reference. That was new to me. I'll have to implement it when I find time.

[Carcul]

Just by curiosity, have someone managed to complete exercise #5?

Carcul

[Jeff]

Hi Carcul, After my mis-identification of the continuous multiple poly-implication loop, I haven't had a chance to look at that grid.