dailysudoku.com

[Bud]

200041000306000500000500090021000000040126080000000200070008000002000703000470806

After basic moves the puzzle is as shown in the diagram. The 2 ALS's are labeled A and B in Box 1 and 3. The 1 grouped conjugates in row 2 are labeled C and D. The logic is as follows. If C=1, A=478 or if D=1, B=3678. In either case r1c3 and r3c9<>78 and r1c2<>8. This move results in 8 cells being identified. I have another example of this technique which I can add to this post if someone wants to see it. I don't think that this technique is new. It would be hard to believe that someone has not used it before.

[ronk]

Bud, without the grouped strong inference (link) in r2, you already have two ALS-xz's for the same eliminations. The 'x' is digit <1> in r3. Either way, it's a nice move.

[Bud]

Thanks for your reply Ron. I still think that 1 move is better than 2 but I respect your opinion. In a sense, the conjugate linked ALS's are quasi or psuedo ALS-XZ's since the 2 ALS's have the same rcd and logically there is no difference between a direct link and and indirect link between the rcd's in the 2 ALS's. In fact in the old forum I had a post about ALS-XZ's that were ER linked.

One other comment. This puzzle has a Sudoku Explainer (SE) rating of 8.3 which usually takes a lot of moves to work. The same is true of my almost doubly-linked ALS-XZ post. Since SE does not use ALS logic, one way I have found to reduce the number of moves is to look for ALS's.

[ronk]

[Bud]

I apologize Ron, My Bad. I now clearly see that the conjugate linkage is redundant. So your way is better. I will say that this is the most powerful singly-linked ALS-XZ I have ever seen. Because of the redundancy I need to trot out my other example.

605420301000050000408700900000080020300000007050010000003206508500090000002005004

After basic moves, the puzzle is as shown in the diagram below. The pattern of interest is in boxes 2 and 8. The ALS labeled A =1389. The ALS labeled B =138. These two ALS's do not even see each other so they need the help of the 3 conjugate labeled C and D in column 5. If C=3, A=189 and if D=3, B=18. In either case r2c4 and and r8c6<>18.

[ronk]

[daj95376]

Ron, why didn't you use?

[PIsaacson]

Bud,

Your last example, 2 ALSs linked via a conjugate, is what I would call a Death Blossom. I'm not sure where it was proposed, but it's not necessary for a DB to be confined to a single stem cell with ALSs hanging off as petals. The stem can be any set of mutually exclusive candidates with ALSs linked to each of the members. In this case, you have the bi-local 3 in column 5 acting as the stem of the DB.

Cheers,
Paul

[ronk]

[PIsaacson]

Ron,

I guess I view DBs as patterns rather than chains/nets. But being of the school that believes there's little (if any) practical difference between the two, I'll concede that the example is a also a fairly simple AIC containing 2 ALSs. Could you supply an example of a DB that satisfies the requirement of needing to be a net? I'm having trouble visualizing this - perhaps because I'm biased to seeing them as patterns???

Cheers,
Paul

[Bud]

Hi Paul,
First of all, let me say that Allan Barker initiated the Death Blossom. I have been able to contact him in the past to ask questions at his site Sudokuone.com and he is very gracious about answering. I think my last post is a good example of a death blossom. Your definition of the db in your first reply is accurate. The problem is you are equating conjugates to a stem cell which is a single cell with two or more candidates. I think Allan would simply call my example "multiple ALS logic". He also uses "single ALS logic" which is a combination of an ALS and conjugates.

Cheers,
Bud

[ronk]

[DonM]

Bud, here's another view about the subject above.

You may be aware of the following links, but your first post indicates you may not be. In the first thread below, you will find examples of ALS Chains using conjugate links just as you do above. The first 3 examples in the 2nd thread below are of the most common form of Death Blossom- which, in that form, is nothing but a 3-Set ALS Chain with a bivalue single-cell middle/second ALS set. There are more complex Death Blossoms, but you don't come across them very often. Incidentally, on the subject of Death Blossom as a net or not: I have the same view as Paul above: When it comes to patterns, the question as to whether the pattern is a net or not is not relevant. Pattern-solving does not involve recognition of nets vs. chains: patterns are patterns, nothing more, nothing less. However, I also agree that the pattern referred to was not a DB as I know it.

http://forum.enjoysudoku.com/als-chains-a-tutorial-asi-3-t6443.html

http://forum.enjoysudoku.com/advanced-als-chains-a-tutorial-asi-3b-t30098.html

The two ALS patterns you came up with are both the same: a 2-set ALS Chain using a conjugate link for the RC. (In this case, the term, 'set' refers specifically to an Almost Locked Set, lest the terminology police choose to make an issue of the number of sets.) They are clever finds in and of themselves and it takes skill to find them. Keep in mind that it is always easier for others to find 'simpler' patterns than the one you used to reach the same eliminations than it is for them to find your pattern in the first place. As one gets more skilled, one will find oneself waking up the next morning and simplifying one's own patterns.

Pattern-solving is a unique skill, different from finding chains. I started as a pure pattern solver and ended up also using AIC chains to solve more difficult puzzles, but the graduation to AICs does not make pattern-solving obsolete. If you find that you can increasingly find ALS patterns such as yours above, you will likely be able to not only find the eliminations from those patterns faster than someone who uses an AIC to find those same eliminations, but you will also be better able to find ALS patterns to use in AICS.

Pattern solving is not only useful in solving in general, it's also fun. As is indicated in the threads those two links refer to, one can often solve some puzzles with nothing but basic methods and ALS chains.

But to repeat myself: those were 2 nice finds, just the way they are.

[Bud]

Thanks Don,
I learned a lot about ALS's from your tutorial. Also thanks to everyone else for your helpful comments.

[ronk]

[DonM]

[ronk]

[DonM]