The New Sudoku Players' Forum

[Mauriès Robert]

Hi all,
I would like to point out that for a while now your comments have nothing to do with my thread!
Maybe you should open a thread called "I'm trying to understand the whips".
Robert

[denis_berthier]

Now i look at the link r9c8{n4 n1} - r9c2{n1 n2}. Why not 9 ?

9 where? A link is a link. There's no 9 in it.
If you mean why not 9 in r9c2{n1 n2}, it's obvious: because n9r9c2 is a z-candidate (linked to the target n9r1c2.

Ok, and r9c8{n4 n1} is a valid link, because 7 is a z-candidate (?) from the first link r1n7{c2 c8}, and c7n2{r9 .} is an impossible link, because in the 3rd link b3n6{r1c7 r2c7} 6 is a ?-candidate in r2c7. Have i got it ?

In part, yes. Some details:

To be clear, I copy the RS here:

Code: Select all

  +----------------+----------------+----------------+
   ! 2    179  39   ! 3569 8    359  ! 16   167 4    !
   ! 47   5    489  ! 469  1    249  ! 268  3    278  !
   ! 134  18   6    ! 349  7    234  ! 5    9    128  !
   +----------------+----------------+----------------+
   ! 356  268  2358 ! 1    49   7    ! 348  45   389  !
   ! 9    4    1    ! 58   3    58   ! 7    2    6    !
   ! 357  78   358  ! 2    49   6    ! 1348 145  1389 !
   +----------------+----------------+----------------+
   ! 146  126  7    ! 348  5    1348 ! 9    146  123  !
   ! 1456 3    459  ! 479  2    149  ! 146  8    17   !
   ! 8    129  249  ! 3479 6    1349 ! 1234 147  5    !
   +----------------+----------------+----------------+

and the whip

Code: Select all

whip[7]: r1n7{c2 c8} - r1n1{c8 c7} - b3n6{r1c7 r2c7} - r8c7{n6 n4} - r9c8{n4 n1} - r9c2{n1 n2} - c7n2{r9 .} ==> r1c2≠9

I wouldn't call r9c8{n4 n1} a valid link; but it's a valid part of this whip because the only other possible value for CSP-Variable r9c8 in the current resolution state, namely 7, is linked to previous rlc n1r1c7. n7r9c8 is a t-candidate. Note that if it disappears before the whip is applied, the whip remains unchanged.

Similarly, the final part c7n2{r9 .} means that there is no possible value for CSP-Variable c7n2 (an obvious contradiction). This is true because the only other candidate for c7n2 is n2r9c7, but is it linked to previous rlc n2r9c2; it is therefore a t-candidate. (It has nothing to do with the z- or t- candidates in b3n6.)

[denis_berthier]

Back to Robert's puzzle then.
Denis, how would you make the elimination -1r13c7 in the first step ?

These are two very different eliminations, with very different complexities. SudoRules would never proceed that way.
But you can reproduce them by the following commands:

Code: Select all

(init "..6....9..75.2.8..9...7...2.3...74.....245.....46...7.8...6...3..1.3.54..4....7..")
(try-to-eliminate 167)
(try-to-eliminate 177)

The result (starting from the same RS) is:

Code: Select all

z-chain[3]: b6n2{r6c7 r4c8} - r7c8{n2 n1} - b3n1{r2c8 .} ==> r6c7≠1
     with z-candidates = n1r3c7 n1r1c7
whip[10]: r1c7{n1 n3} - r3c7{n3 n6} - b3n1{r3c7 r2c8} - b1n1{r2c1 r3c2} - r3n8{c2 c3} - r3n3{c3 c4} - c4n4{r3 r7} - r7n7{c4 c3} - r5c3{n7 n9} - r5c7{n9 .} ==> r7c7≠1

Size 10 is the same as in Robert's pattern, but the first elimination is much simpler.

[eleven]

So you agree with me, that Robert's way of solving is nearer to mine than to yours ?

[denis_berthier]

Different people have different ways of solving. I don't know what yours is.

[eleven]

Well, as you could see, i have no problems to translate Robert's chain into my usual way of writing chains (so it could be by myself), while your way is very different. I guess the reason is, that we are both manual solvers.
Nevertheless you claimed, he had something copied from you, didn't you ?

[denis_berthier]

Well, as you could see, i have no problems to translate Robert's chain into my usual way of writing chains (so it could be by myself), while your way is very different. I guess the reason is, that we are both manual solvers.
Nevertheless you claimed, he had something copied from you, didn't you ?

Once more the manual solver argument of people who have no argument.

[eleven]

yes i know, that you can't understand that. So please don't claim again, that Robert copied anything from you. We never needed yor strange solving theory.

[champagne]

Hi eleven,

As you (but I am not exactly a manual solver) I had difficulties with the whips

whip[7]: r1n7{c2 c8} - r1n1{c8 c7} - b3n6{r1c7 r2c7} - r8c7{n6 n4} - r9c8{n4 n1} - r9c2{n1 n2} - c7n2{r9 .} ==> r1c2≠9

when I tried to understand why it was different of the image given by yzfwsf.

In fact, yzfwsf had the answer. To be in a common logic, you had to add as start 9r1c2.
then, as I wrote earlier, the whip becomes quasi identical to a dynamic forcing chain expansion as in Sudoku Explainer

Code: Select all

a) 9r1c2 => -1r1c2,-7r1c2;-9r9c2             missing 
b) 7r1c8 => -1r1c8 ;-6r1c8 ;-1r8c7;-7r9c8    r1n7{c2 c8}
c)(-1r1c2,-1r1c8) 1r1c7=>-6r1c7              r1n1{c8 c7}
d)(-6r1c8,-6r1c7) 6r2c7=>-6r8c7 ;-2r2c7      b3n6{r1c7 r2c7}
e)(-1r8c7,-6r8c7)4r8c7=>-4r9c8               r8c7{n6 n4}
f)(-4r9c8 ;-7r9c8)1r9c8=>-1r9c2              r9c8{n4 n1}
g)(-1r9c2 ;-9r9c2)2r9c2=>-2r9c7              r9c2{n1 n2}
and now the last pieces of the whip    - c7n2{r9 .} ==> r1c2≠9
Clearly we have no “2” in the column 7 

Why is the start missing??? I don't know.
If there is another logic for the whip without the start, I don't understand it.

Adding the start, we are very close to what you could see in Mauries's expansion and in many eliminations done by manual solvers.
As you, I don't like whips produced without explicit reference to the candidates cleared up stream if you follow the whip left to right. The diagram of our friend yzfwsf is much easier to follow.
And for me, unless you have the chance to have groups, such sequences are not reversible contrary to the AIC's and AIC's nets.

[denis_berthier]

yes i know, that you can't understand that. So please don't claim again, that Robert copied anything from you. We never needed yor strange solving theory.

"WE"? You now believe you are "we the people"?
Because you pretended you didn't understand whips and you asked obvious questions about them, do you think I hadn't anticipated the outcome of all your phoney questions? The only purpose what to make believe you didn't understand anything about whips. If that was true, why have you systematically been criticising them for years?
WE never needed opinions based only on personal hatred.

Like it or not, I repeat it: Robert's resolution paths are not the result of only his "Theory of Tracks" (in which there is indeed no theory at all). The paths and chains he presents are largely inspired:
1) by my notion of length (as opposed to the notion of number of inferences in ALL the other solvers)
2) by Defise's fewer step approach for reducing the number of steps.

And WE don't need the opinion of someone who believes he is the reference of all the manual solvers.

[denis_berthier]

Why is the start missing??? I don't know.
If there is another logic for the whip without the start, I don't understand it.

The start is not missing. If you had read the definitions instead of typing on your keyboard faster than your brain, you'd know that the target is written at the end.

And for me, unless you have the chance to have groups, such sequences are not reversible contrary to the AIC's and AIC's nets.

Whips are not designed to be reversible. If you want groups, there are g-whips.

[denis_berthier]

.
GENERAL REMARK.
This thread is a good illustration of the workings of asocial networks.
90% of what is said could be avoided if people had some knowledge of what they are talking about.

[champagne]

Why is the start missing??? I don't know.
If there is another logic for the whip without the start, I don't understand it.

The start is not missing. If you had read the definitions instead of typing on your keyboard faster than your brain, you'd know that the target is written at the end.

in another words, if you can make if difficult, why should you make it easy

and stop for me in endless crazy discussions but I know that my brain is not at the right level

[denis_berthier]

Why is the start missing??? I don't know.
If there is another logic for the whip without the start, I don't understand it.

The start is not missing. If you had read the definitions instead of typing on your keyboard faster than your brain, you'd know that the target is written at the end.

in another words, if you can make if difficult, why should you make it easy

Yesss, that's exactly what I meant. I understand that reading a definition before talking of what you don't understand is much harder than typing random remarks on a keyboard.

[champagne]

Yesss, that's exactly what I meant. I understand that reading a definition before talking of what you don't understand is much harder than typing random remarks on a keyboard.

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