The New Sudoku Players' Forum

[ArkieTech]

Code: Select all

 *-----------*
 |...|7..|.8.|
 |59.|...|.7.|
 |...|9.4|.3.|
 |---+---+---|
 |...|3..|...|
 |...|.1.|.58|
 |2..|...|...|
 |---+---+---|
 |.6.|...|..2|
 |9..|25.|71.|
 |..5|16.|...|
 *-----------*


Play/Print this puzzle online

[SteveG48]

Code: Select all

 *--------------------------------------------------*
 | 4   b13  d26   | 7   a3-2  5    | 16   8    9    |
 | 5    9    38   | 6    38   1    | 2    7    4    |
 | 168  178  267  | 9    28   4    | 16   3    5    |
 *----------------+----------------+----------------|
 | 18   5    189  | 3    79   6    | 4    2    17   |
 | 36  c37  d67   | 4    1    2    | 9    5    8    |
 | 2    14   149  | 5    79   8    | 3    6    17   |
 *----------------+----------------+----------------|
 | 13   6    13   | 8    4    7    | 5    9    2    |
 | 9    48   48   | 2    5    3    | 7    1    6    |
 | 7    2    5    | 1    6    9    | 8    4    3    |
 *--------------------------------------------------*


(3)r1c5 = r1c2 - (3=7)r5c2 - (7=62)r15c3 => -2 r1c5 ; stte

[SteveG48]

The first Death Blossom that I've ever picked:

Code: Select all

 *--------------------------------------------------*
 | 4  TU13  T26   | 7   T23   5    | 6-1  8    9    |
 | 5    9    38   | 6    38   1    | 2    7    4    |
 | 168  78-1 267  | 9    28   4    | 16   3    5    |
 *----------------+----------------+----------------|
 | 18   5    189  | 3    79   6    | 4    2    17   |
 | 36  U37  S67   | 4    1    2    | 9    5    8    |
 | 2    4-1  149  | 5    79   8    | 3    6    17   |
 *----------------+----------------+----------------|
 | 13   6    13   | 8    4    7    | 5    9    2    |
 | 9    48   48   | 2    5    3    | 7    1    6    |
 | 7    2    5    | 1    6    9    | 8    4    3    |
 *--------------------------------------------------*


Stem [67]r5c3
Petal T: [1236]r1c235 (locked by stem 6)
Petal U: [137]r15c2 (locked by stem 7) => -1 r1c7,r36c2 ; stte

[pjb]

Code: Select all

 4       13      26     | 7      23     5      | 16     8      9     
 5       9       38     | 6      38     1      | 2      7      4     
 168     178     267    | 9      28     4      | 16     3      5     
------------------------+----------------------+---------------------
 18      5      a89-1   | 3     a79     6      | 4      2     a17     
 36      37      67     | 4      1      2      | 9      5      8     
 2       14     a49-1   | 5     a79     8      | 3      6     a17     
------------------------+----------------------+---------------------
 13      6       13     | 8      4      7      | 5      9      2     
 9       48      48     | 2      5      3      | 7      1      6     
 7       2       5      | 1      6      9      | 8      4      3     


DP r46c359 => -1 r46c3; stte

Phil

[bat999]

(3)r1c5 = r1c2 - (3=7)r5c2 - (7=62)r15c3 => -2 r1c5 ; stte

@SteveG48
Not sure what happened here.
Did you take a punt?
Tried it with r1c5 set at 3, then worked round the chain to leave 26 in r13c3.
And it finished OK, so deduce that r1c5 must be 3 because everything is sweet in columns 23?
Is that it?

[gurth]

[gurth]

(3)r1c5 = r1c2 - (3=7)r5c2 - (7=62)r15c3 => -2 r1c5 ; stte

@SteveG48
Not sure what happened here.
Did you take a punt?
Tried it with r1c5 set at 3, then worked round the chain to leave 26 in r13c3.
And it finished OK, so deduce that r1c5 must be 3 because everything is sweet in columns 23?
Is that it?

If I expanded
(3)r1c5 = r1c2 - (3=7)r5c2 - (7=62)r15c3 => -2 r1c5 ; stte
to the unelided version

(3)r1c5 = r1c2 - (3=7)r5c2 - (7=6)r5c3 - (6=2)r1c3 => -2 r1c5 ; stte

would that be clearer to you? The chain is saying that there must be a (3)r1c5 OR a (2)r1c3.
A 2 at r1c5 would destroy both these possibilities; that is why it cannot be there and must be removed.

[bat999]

... would that be clearer to you? The chain is saying...

Not really, because I don't understand that Eureka notation properly.
I know that a 3 at r1c5 works OK (I solved the puzzle myself using a long-winded method).
Though (to me) the post doesn't seem to prove that it must be a 3 at r1c5.
Shouldn't there be some indication of what would happen if it was a 2 instead?
Or maybe that's implied in that code.
Anyway, I'll take your word for it.

[Leren]

Code: Select all

*--------------------------------------------------------------*
| 4    c13   e26     | 7     23    5      |c16    8     9      |
| 5     9     38     | 6     38    1      | 2     7     4      |
| 18-6  178   267    | 9     28    4      | 16    3     5      |
|--------------------+--------------------+--------------------|
| 18    5     189    | 3     79    6      | 4     2     17     |
|a36   b37    7-6    | 4     1     2      | 9     5     8      |
| 2     14    149    | 5     79    8      | 3     6     17     |
|--------------------+--------------------+--------------------|
| 13    6     13     | 8     4     7      | 5     9     2      |
| 9     48    48     | 2     5     3      | 7     1     6      |
| 7     2     5      | 1     6     9      | 8     4     3      |
*--------------------------------------------------------------*

(6=3) r5c1 - r5c2 = (3-1) r1c2 = (1-6) r1c7 = (6) r1c3 => - 6 r3c1, r5c3; stte

Leren

[eleven]

I don't know, what a Death Blossom is. While Andrew Stuart starts from a single "stem" cell, there is none in the example by Mike Barker, who gave the technique the name.

Bat, the logic here is simply:
r5c3=6 -> r1c235=123 (and 1r1c2)
r6c3=7 -> r15c2=13 (and 1r1c2)

[Added:]
btw in your notation you could write:
A=r5c2, B=r5c3, X=r1c2
A<>7: r5c2=3->r1c2=1
B<>7: r5c3=6->r1c3=2->r1c5=3->r1c2=1
=>r1c2=1

Logic in Mike's sample:
r13c9=2 -> r69c9=49 (and r9c9=9) -> r8c7=2 -> r4c7<>2
r13c7=2 -> r4c7<>2

[SteveG48]

I don't know, what a Death Blossom is. While Andrew Stuart starts from a single "stem" cell, there is none in the example by Mike Barker, who gave the technique the name.

To me, a Death Blossom is just a special case of a Kraken cell solution in which each of the links from one of the "stem" (Kraken) cell candidates to the target is a single ALS (petal) locked if the candidate is set in the stem cell. I think that's what Mike Barker says.

[eleven]

Well, in his sample there is only one ALS, but with an additional link ...

[SteveG48]

... would that be clearer to you? The chain is saying...

Not really, because I don't understand that Eureka notation properly.
I know that a 3 at r1c5 works OK (I solved the puzzle myself using a long-winded method).
Though (to me) the post doesn't seem to prove that it must be a 3 at r1c5.
Shouldn't there be some indication of what would happen if it was a 2 instead?
Or maybe that's implied in that code.
Anyway, I'll take your word for it.

Hi, Bat. No need to take anyone's word for it. The Eureka notation simply means that if r1c5 is not a 3 then r1c3 must be a 2. That obviously would eliminate a 2 in r1c5. What isn't stated but is generally accepted as clear, is that if r1c5 is a 3 then it can't be a 2, so either way r1c5 is not 2.

[bat999]

@SteveG48
"btw in your notation you could write..."
It's not the same thing as your original post, but it has the same effect.

"Bat, the logic here is simply..."
You are toggling the value of r5c3(67), testing what happens to r1c5.
That was not apparent to me in your original post.

Leren's post looked OK.
If r5c1 is 6 it knocks out the two sixes at r3c1, r5c3.
If r5c1 is 3 it puts a 6 into r1c3 to zap them.

[gurth]

... would that be clearer to you? The chain is saying...

Not really, because I don't understand that Eureka notation properly.
I know that a 3 at r1c5 works OK (I solved the puzzle myself using a long-winded method).
Though (to me) the post doesn't seem to prove that it must be a 3 at r1c5.
Shouldn't there be some indication of what would happen if it was a 2 instead?
Or maybe that's implied in that code.
Anyway, I'll take your word for it.

Bat, there's really nothing to the Eureka notation, it's just a series of simple logical steps strung together; you have developed a strange mental block which should be easily overcome. All you have to do is to understand the meaning of the symbols '=' and '-' as used in AICs (which are the same as Eureka).
A=B is a 'strong link', meaning that either A or B (or both!) must be true. Therefore, if NOT A, then B is true.
A-B is a 'weak link', meaning that at most one (or neither!) can be true. Therefore, if A is true, then B is NOT true.

Two examples:
A=B-C=D means: 'If NOT A, then B true and then C false and then D true'. But this assumption 'NOT A' is only one possibility, which has the result 'D is true'.
The other possibility is that A is true. The chain actually deduces nothing in that case. So you are left with the fact that either D is true, or A is true.
Are you with me so far?