The New Sudoku Players' Forum

by **Mauriès Robert** » Thu Jan 20, 2022 10:31 am

Hi all,
I propose this unoriginal but quite difficult puzzle.
I am interested in your resolutions.

..6....9..75.2.8..9...7...2.3...74.....245.....46...7.8...6...3..1.3.54..4....7..

puzzle: Show

my resolution: Show

Robert

by **DEFISE** » Fri Jan 21, 2022 9:21 am

Hi Robert,
It's a rather short solution for a manual solver !
With my computer I only find a little shorter path, as for your previous puzzle:

Hidden Text: Show

N.B: W-rating = 9

by **DEFISE** » Fri Jan 21, 2022 9:44 am

Canceled

by **yzfwsf** » Fri Jan 21, 2022 9:59 am

Hidden and Locked Candidates
Dynamic Contradiction Chain: If r9c5=8 Then r3c3=3 And r3c3<>3 simultaneously,so r9c5<>8

Hidden Text: Show

Dynamic Contradiction Chain: If r2c8=1 Then r1c6=8 And r1c6<>8 simultaneously,so r2c8<>1

Hidden Text: Show

Locked Candidates 1 (Pointing): 1 in b3 => r5c7<>1,r6c7<>1,r7c7<>1
Dynamic Contradiction Chain: If r7c4=5 Then r8c1=2 And r8c1<>2 simultaneously,so r7c4<>5

Hidden Text: Show

Hidden Single: 5 in r7 => r7c2=5
Dynamic Contradiction Chain: If r2c6<>6 Then r6c5=8 And r6c5<>8 simultaneously,so r2c6=6

Hidden Text: Show

stte

by **DEFISE** » Fri Jan 21, 2022 1:18 pm

If we don't bother with the length of chains, then I also have this:

Single(s): 7r1c9, 4r2c9, 4r1c1, 2r1c2, 5r3c8, 3r6c6
Box/Line: 8r1b2 => -8r3c4 -8r3c6

whip[14]: c7n6{r3 r5}- r3n6{c7 c6}- r3n4{c6 c4}- r3n3{c4 c3}- r2c1{n3 n1}- r5c1{n1 n7}- b4n6{r5c1 r4c1}- c2n6{r5 r8}- r8c1{n6 n2}- r6n2{c1 c7}- c7n9{r6 r7}- r8c9{n9 n8}- r8c6{n8 n9}- r2c6{n9 .} => -1r3c7

whip[19]: r1c7{n1 n3}- r3c7{n3 n6}- r2n6{c8 c6}- r2n9{c6 c4}- r2n3{c4 c1}- r3c3{n3 n8}- r3n3{c3 c4}- c4n4{r3 r7}- c4n7{r7 r8}- c1n7{r8 r5}- r5c3{n7 n9}- r5c7{n9 n1}- r7n1{c7 c6}- r1c6{n1 n8}- r8n8{c6 c9}- r5c9{n8 n6}- c2n6{r5 r8}- c2n9{r8 r7}- r7n5{c2 .}
=> -1r2c8

Single(s): 1r1c7, 8r1c6, 5r1c5, 3r1c4
Naked pairs: 29c7r67 => -9r5c7

whip[8]: b6n2{r4c8 r6c7}- c7n9{r6 r7}- r7c2{n9 n5}- c4n5{r7 r9}- c4n8{r9 r8}- r8c9{n8 n6}- r4n6{c9 c1}- c2n6{r5 .} => -8r4c8

whip[12]: r8n8{c9 c4}- c4n7{r8 r7}- r7n4{c4 c6}- r7n1{c6 c8}- c8n2{r7 r4}- b4n2{r4c1 r6c1}- r8n2{c1 c6}- r9n2{c6 c3}- r9n3{c3 c1}- r9n6{c1 c9}- r4n6{c9 c1}- c1n5{r4 .} => -8r9c8

STTE

by **yzfwsf** » Fri Jan 21, 2022 1:34 pm

Can you omit Nake Pair for the solution path， nothing else, just curious.

by **Mauriès Robert** » Fri Jan 21, 2022 2:18 pm

Hi François,
This four-step resolution is in line with level 4 TDP of the puzzle.
Robert

by **DEFISE** » Fri Jan 21, 2022 2:55 pm

yzfwsf wrote:Can you omit Nake Pair for the solution path， nothing else, just curious.

Yes, removing the NP does not change at all afterwards.

by **DEFISE** » Fri Jan 21, 2022 3:04 pm

Mauriès Robert wrote:Hi François,
This four-step resolution is in line with level 4 TDP of the puzzle.
Robert

Yes but I have this possibility too:

Single(s): 7r1c9, 4r2c9, 4r1c1, 2r1c2, 5r3c8, 3r6c6
Box/Line: 8r1b2 => -8r3c4 -8r3c6

whip[19]: r1c7{n1 n3}- r3c7{n3 n6}- r2n6{c8 c6}- r2n9{c6 c4}- r2n3{c4 c1}- r3c3{n3 n8}- r3n3{c3 c4}- c4n4{r3 r7}- c4n7{r7 r8}- c1n7{r8 r5}- r5c3{n7 n9}- r5c7{n9 n1}- r7n1{c7 c6}- r1c6{n1 n8}- r8n8{c6 c9}- r5c9{n8 n6}- c2n6{r5 r8}- c2n9{r8 r7}- r7n5{c2 .}
=> -1r2c8

Box/Line: 1b3c7 => -1r5c7 -1r6c7 -1r7c7
Naked pairs: 29c7r67 => -9r5c7

g-whip[11]: c3n3{r3 r9}- r3c3{n3 n8}- r3c2{n8 n1}- c7n1{r3 r1}- b3n3{r1c7 r3c7}- c7n6{r3 r5}- c2n6{r5 r8}- b7n9{r8c2 r7c23}- r7c7{n9 n2}- r6n2{c7 c1}- c3n2{r3 .}
=> -3r2c1

Single(s): 1r2c1, 8r3c2, 3r3c3, 3r9c1, 5r7c2
Box/Line: 6r9b9 => -6r8c9

S2-whip[13]: c1n5{r4 r6}- r6n2{c1 c7}- c7n9{r6 r7}- r8c9{n9 n8}- r6n8{c9 c5}- c4n8{r4 NP: n58r19}- r1n3{c4 c7}- r2c8{n3 n6}- r2c6{n6 n9}- r8c6{n9 n2}- c1n2{r8 r4}- r4n6{c1 .}
=>-5r4c9

STTE

So TDP level <= 3

Website · by **denis_berthier** » Fri Jan 21, 2022 3:07 pm

DEFISE wrote:It's a rather short solution for a manual solver !
With my computer I only find a little shorter path, as for your previous puzzle

Who could seriously believe that Robert's solution in 10 steps was found manually? Considering the number of paths one should try to find this, this is totally impossible.

The simplest-first solution has 36 steps in W9. Usually, a first try at reducing the number of steps by the fewer steps algorithm divides this number by at most 2. Each try of the fewer steps algorithms supposes lots of computations, for each remaining candidate.
Moreover, the next tries further reduce the number of steps only slowly. An important number of tries is necessary before reducing it from 36 to 10.

The obvious conclusion is, in the same way as he named anti-tracks his limited understanding of braids (or S-braids for some of them), Robert now applies without saying some version of the fewer steps algorithm.

by **Mauriès Robert** » Fri Jan 21, 2022 4:01 pm

denis_berthier wrote:Who could seriously believe that Robert's solution in 10 steps was found manually? Considering the number of paths one should try to find this, this is totally impossible.

Well, you're wrong and you're slanderous, because it is indeed manually and without the help of any software that I built this solution. Of course it took me some time and several tries.

denis_berthier wrote:The obvious conclusion is, in the same way as he named anti-tracks his limited understanding of braids (or S-braids for some of them), Robert now applies without saying some version of the fewer steps algorithm.

And what's more, you are dishonest in writing this, because you know very well that I have defined and used anti-tracks for a very long time and long before I was interested in your whips and braids.
The only reason I present resolutions in several stages on this forum, therefore with short anti-tracks, is to adapt to the spirit of this forum which requires that the construction of the sequences be detailed.
Robert

Website · by **denis_berthier** » Fri Jan 21, 2022 4:28 pm

Mauriès Robert wrote:you know very well that I have defined and used anti-tracks for a very long time and long before I was interested in your whips and braids.

What I know very well is, I defined and published whips and braids much before you wrote anything about your ill-understood, downgraded version of them, under a different name. Anyone can check the dates. And for anyone who can read the technical details, it is obvious you had read my books before writing anything.

Mauriès Robert wrote:The only reason I present resolutions in several stages on this forum, therefore with short anti-tracks, is to adapt to the spirit of this forum which requires that the construction of the sequences be detailed.

This is total nonsense. Solutions with both short chains + short resolution paths are never a mere "adaptation". They require huge quantities of computation. So, NO, absolutely no, you cannot have found such solutions manually.

by **Mauriès Robert** » Fri Jan 21, 2022 5:21 pm

denis_berthier wrote:What I know very well is, I defined and published whips and braids much before you wrote anything about your ill-understood, downgraded version of them, under a different name. Anyone can check the dates. And for anyone who can read the technical details, it is obvious you had read my books before writing anything.

I don't claim to have developed TDP before you developed your theories, that's not the point, but you can't say I read your books before, that's not true. I designed TDP completely on my own and it was later that I discovered similar techniques (virtual colouring, forced chains, etc.). It was only much later that I discovered your first book and wrote to you to ask your opinion on TDP and you replied (I have your answer). So I never used your books as inspiration for the TDP, whether you like it or not.

denis_berthier wrote:This is total nonsense. Solutions with both short chains + short resolution paths are never a mere "adaptation". They require huge quantities of computation. So, NO, absolutely no, you cannot have found such solutions manually.

And yet, it is by hand that I have solved this grid and all the others I propose. I understand that this bothers you, but that's how it is.

Website · by **denis_berthier** » Fri Jan 21, 2022 5:36 pm

Mauriès Robert wrote:
denis_berthier wrote:What I know very well is, I defined and published whips and braids much before you wrote anything about your ill-understood, downgraded version of them, under a different name. Anyone can check the dates. And for anyone who can read the technical details, it is obvious you had read my books before writing anything.

I don't claim to have developed TDP before you developed your theories, that's not the point,

That's the whole point and I can easily prove it, contrary to your empty claims below.

Mauriès Robert wrote:but you can't say I read your books before, that's not true. I designed TDP completely on my own and it was later that I discovered similar techniques (virtual colouring, forced chains, etc.). It was only much later that I discovered your first book and wrote to you to ask your opinion on TDP and you replied (I have your answer). So I never used your books as inspiration for the TDP, whether you like it or not.

You can deny the obvious, it remains obvious.
You have my answer and so what?
Moreover,
- you have now obviously adopted my notion of length of a chain, unique to my definitions. You initially had no notion of length in your tracks and you've even repeated multiple times that length isn't important.
- and you've also obviously adopted a version of François's fewer step algorithm.
Two examples of how you progress "on your own".

Mauriès Robert wrote:
denis_berthier wrote:This is total nonsense. Solutions with both short chains + short resolution paths are never a mere "adaptation". They require huge quantities of computation. So, NO, absolutely no, you cannot have found such solutions manually.

And yet, it is by hand that I have solved this grid and all the others I propose. I understand that this bothers you, but that's how it is.

Why would this bother me. What you claim is computationally impossible.

by **DEFISE** » Fri Jan 21, 2022 6:06 pm

denis_berthier wrote:
DEFISE wrote:It's a rather short solution for a manual solver !
With my computer I only find a little shorter path, as for your previous puzzle

1)
Who could seriously believe that Robert's solution in 10 steps was found manually? Considering the number of paths one should try to find this, this is totally impossible.
...
....
2)
The obvious conclusion is, in the same way as he named anti-tracks his limited understanding of braids (or S-braids for some of them),
3) Robert now applies without saying some version of the fewer steps algorithm.

1) It should nevertheless be pointed out that Robert does not work only with paper and pencil.
He obviously has graphic tools and he can notably know if a track from any candidate leads to a contradiction (using singles and perhaps more) by clicking on a button.
It's not a secret, everyone can check it by going to assistant-sudoku.com

2) So I would like to know what you think of P.O.’s chains....

3) Truly, I don't think this algorithm "Fewer-Steps" is some “confidential defense”, you yourself made a thread about it: [Advanced solving techniques] – [Reducing the number of steps].

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