The New Sudoku Players' Forum

[Hajime]

In this post http://forum.enjoysudoku.com/post266913.html#p266913 I extracted the next puzzle:

This puzzle, which I may have taken from the Patterns Game, ran for 7+ minutes, and no solution was forthcoming!!

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..1.....2..231..4.56...27...3........2....5....7..1.8...6.5...9.1...4...9.....3.4

When pasting it into SukakuSolver 1.17.7.1 the first hint came up:

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Dynamic Region Forcing Chains
With this solving technique, we will prove the following assertions:
If r1c1 contains the value 4, then r1c1 cannot contain the value 7
If r1c2 contains the value 4, then r1c1 cannot contain the value 7
If r3c3 contains the value 4, then r1c1 cannot contain the value 7
Because the value 4 cannot be placed elsewhere in the block, and the results are the same, we can conclude that r1c1 cannot contain the value 7.
...

And the next hint: same for candidate 8.

In my implementation in SiSeSuSo (not released yet) with "Forcing Net" (a T&E for 1 depth) I get :

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r1c1=8 --> r5c1 is empty => (-8)r1c1
r1c1=7 --> r5c1 is empty => (-7)r1c1


meaning that if you try a cell (r1c1=8) then you end up somewhere with an empty cell (no solution, no candidates).
Conform http://sudopedia.enjoysudoku.com/Forcing_Net.html

My question: Does "Dynamic Region Forcing Chains" and "Forcing Net" lead to the same eliminations?

[champagne]

I ran your puzzle with skfr (cloning more or less Sudoku Explainer).
The first step clears 7r1c1 8r1c1 using dynamic forcing chains

[Hajime]

I ran your puzzle with skfr (cloning more or less Sudoku Explainer).
The first step clears 7r1c1 8r1c1 using dynamic forcing chains

That is what I said.
And also what "Forcing Net" does, so what is the difference ?

[champagne]

I ran your puzzle with skfr (cloning more or less Sudoku Explainer).
The first step clears 7r1c1 8r1c1 using dynamic forcing chains

That is what I said.
And also what "Forcing Net" does, so what is the difference ?

I would not answer in a wrong way but

Any process leading to a contradiction tells you that the start point is wrong.

Expanding a "true" till a contradiction is used in many ways in the sudoku solving field.

"Dynamic forcing chains" refers to a specific set of rules used in the expansion process leading to the contradiction.
"Dynamic forcing chains plus " does the same with another set or rules for the expansion...

Kites, Sky_scrapers, AICs can be seen as the simplest sets of rules used in such an expansion (others sees them as patterns). You can have in this specific case a reduced set of rules leading to the contradiction.

As I don't know what is your set of rules for the expansion, I can't make more precise comments.

[Hajime]

Thank you champagne. You are quite right.
What I meant with

Conform http://sudopedia.enjoysudoku.com/Forcing_Net.html

if I implement "Forcing Net", then all of those dynamic forcing chains are included?
From the SE rating list:

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8.8-9.6: Dynamic Forcing Chains (common 8.8-9.4; rare 8.7 and 9.5(9.6?))
9.1-10.1: Dynamic Forcing Chains(+) (comon 9.4-10.1; rare 9.3 and 10.2; ?9.1-9.2)
9.9-10.9: Dynamic Forcing Chains(+Forcing Chains) (common 10.2-10.7;
          rare 10.1 and 10.8(10.9?); ultra rare 9.9-10.0)
10.8-11.5?: Dynamic Forcing Chains(+Multiple Forcing Chains)
11.4-11.9: Dynamic Forcing Chains(+Dynamic Forcing Chains) 12.0-12.7(Pencilmarks)


in http://forum.enjoysudoku.com/revision-of-se-ratings-and-resolution-rules-t36376-30.html?hilit=revision#p292744

[creint]

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if I implement "Forcing Net", then all of those dynamic forcing chains are included?

Depends on how you implement it.
Using almost singles, almost group, almost set, almost fish.
When net is built then you can try to do the same but on the net as a new sudoku. What I have read from SE code is that it only does 1 extra layer. That part is the slowest part.
When you have done that it should be the same as what Sudoku Explainer does.

There are some ways for building the net.
With almost singles, almost group and no extra layers then you can solve up to SE 10.