The New Sudoku Players' Forum

[DonM]

The long answer, since I'm stuck here holding purses while the girls Xmas shop:

Okay Luke, I'm not getting this: Since when do women leave their purses behind to go shopping?

[Luke]

The long answer, since I'm stuck here holding purses while the girls Xmas shop:

Okay Luke, I'm not getting this: Since when do women leave their purses behind to go shopping?

You kiddin me? Read it n weep

[DonM]

The long answer, since I'm stuck here holding purses while the girls Xmas shop:

Okay Luke, I'm not getting this: Since when do women leave their purses behind to go shopping?

You kiddin me? Read it n weep

Hmm. I stand corrected!

[David P Bird]

My disciplines don't allow kraken nodes but do allow split nodes in desperate situations, so here I can merge two chains into one to produce a one-stepper.

Code: Select all

 *-----------------------*-----------------------*-----------------------*
 |  16     3      45     |  46     2456   259 a  |  8      19 b   7      |
 |  16 d   2      57     |  8      56 e   579    |  19 c   4      3      |
 |  9      8      47     |  347    34     1      |  6      2      5      |
 *-----------------------*-----------------------*-----------------------*
 |  4      1      3      |  2      9      6      |  7      5      8      |
 |  8      5      9      |  137    13     37     |  4      6      2      |
 |  7      6      2      |  5      8      4      |  3      19     19     |
 *-----------------------*-----------------------*-----------------------*
 |  5      4      1      |  9      7      8      |  2      3      6      |
 |  3      9      8      |  146    12456  25 e   |  15 d   7      14     |
 |  2      7      6      |  134    1345   35     |  159    8      149    |
 *-----------------------*-----------------------*-----------------------*
 
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1#2=65)r2c1,r8c7 - (65=52)r2c5,r8c6 => r1c6 <> 25 stte

Seasons Gruntings to all,

DPB

[JC Van Hay]

A two-stepper ...

Code: Select all

+---------------+---------------------+---------------+
| 16  3  (45)   | (46)  2456   259    | 8     19  7   |
| 16  2  (+7-5) | 8     (56)   (59-7) | (19)  4   3   |
| 9   8  47     | 347   34     1      | 6     2   5   |
+---------------+---------------------+---------------+
| 4   1  3      | 2     9      6      | 7     5   8   |
| 8   5  9      | 137   13     37     | 4     6   2   |
| 7   6  2      | 5     8      4      | 3     19  19  |
+---------------+---------------------+---------------+
| 5   4  1      | 9     7      8      | 2     3   6   |
| 3   9  8      | 146   12456  (+2-5) | (15)  7   14  |
| 2   7  6      | 134   1345   35     | 159   8   149 |
+---------------+---------------------+---------------+

XYWing[(5=4)r1c3-(4=6)r1c4-(6=5)r2c5]-(5=7)r2c3-7r2c6=*XYWing[(5=*9)r2c6-(9=1)r2c7-(1=5)r8c7]-(5=2)r8c6; ste

[ronk]

My disciplines don't allow kraken nodes but do allow split nodes in desperate situations, so here I can merge two chains into one to produce a one-stepper.

Code: Select all

 *-----------------------*-----------------------*-----------------------*
 |  16     3      45     |  46     2456   259 a  |  8      19 b   7      |
 |  16 d   2      57     |  8      56 e   579    |  19 c   4      3      |
 |  9      8      47     |  347    34     1      |  6      2      5      |
 *-----------------------*-----------------------*-----------------------*
 |  4      1      3      |  2      9      6      |  7      5      8      |
 |  8      5      9      |  137    13     37     |  4      6      2      |
 |  7      6      2      |  5      8      4      |  3      19     19     |
 *-----------------------*-----------------------*-----------------------*
 |  5      4      1      |  9      7      8      |  2      3      6      |
 |  3      9      8      |  146    12456  25 e   |  15 d   7      14     |
 |  2      7      6      |  134    1345   35     |  159    8      149    |
 *-----------------------*-----------------------*-----------------------*
 
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1#2=65)r2c1,r8c7 - (65=52)r2c5,r8c6 => r1c6 <> 25 stte

When the shared chain segment is short (two strong inferences, in this case), I don't see the merger as simpler than expressing the two chains separately.

(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=6)r2c1 - (6=5)r2c5 => r1c6<>5
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=5)r8c7 - (5=2)r8c6 => r1c6<>2 stte

It might allow someone to claim they solved the puzzle with a single step, as you did, but I challenge that claim as well.

[daj95376]

Luke said the XX members left their purses ... NOT their credit cards!!!

He should have taken them to the Pleasanton Mall. It would have been a bit of a drive, but he would have gotten away from the fog bank ... and he could have seen the sun from a window seat in the bar there. _ _

[SteveG48]

When the shared chain segment is short (two strong inferences, in this case), I don't see the merger as simpler than expressing the two chains separately.

(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=6)r2c1 - (6=5)r2c5 => r1c6<>5
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=5)r8c7 - (5=2)r8c6 => r1c6<>2 stte

It might allow someone to claim they solved the puzzle with a single step, as you did, but I challenge that claim as well.

Hmm. I think it qualifies as a single step. A single assumption, that r1c6 is not a 9, leads to the conclusion that it is neither a 5 nor a 2 as well, a contradiction. That seems as much a single step as the Kraken argument, which comes down to 3 parallel chains, all leading to the same conclusion and comprising all of the possibilities.

[daj95376]

When the shared chain segment is short (two strong inferences, in this case), I don't see the merger as simpler than expressing the two chains separately.

(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=6)r2c1 - (6=5)r2c5 => r1c6<>5
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=5)r8c7 - (5=2)r8c6 => r1c6<>2 stte

It might allow someone to claim they solved the puzzle with a single step, as you did, but I challenge that claim as well.

Hmmm. The way I see it, your two chains can form a network representation of a discontinuous loop. And thus qualify as a single-stepper. However, I'm not a fan of DPB's representation of the network.



I am not a fan of the current trend of making networks look like chains. However, I have succumbed in my own posts of late because of the convenience of using memory to portray secondary eliminations (from networks) as part of a psudo-chain structure.

In addition, I believe that the definition of AIC should be altered to allow the initial (false) assumption to be (selectively) carried forward in its own cell(s). The following would then be an acceptable AIC "discontinuous loop" (using a lasso).

Code: Select all

 +-----------------------------------------------------------------------+
 |  16     3      45     |  46     2456   259    |  8      19     7      |
 |  16     2      57     |  8      56     579    |  19     4      3      |
 |  9      8      47     |  347    34     1      |  6      2      5      |
 |-----------------------+-----------------------+-----------------------|
 |  4      1      3      |  2      9      6      |  7      5      8      |
 |  8      5      9      |  137    13     37     |  4      6      2      |
 |  7      6      2      |  5      8      4      |  3      19     19     |
 |-----------------------+-----------------------+-----------------------|
 |  5      4      1      |  9      7      8      |  2      3      6      |
 |  3      9      8      |  146    12456  25     |  15     7      14     |
 |  2      7      6      |  134    1345   35     |  159    8      149    |
 +-----------------------------------------------------------------------+
 # 44 eliminations remain

 (9*)r1c6=r1c8-(9=165)r2c715-(*95=2)r1c6-(2=5)r8c6-(5=1)r8c7-(1=9)r2c7-r1c8=(9)r1c6


[SteveG48]

Hmmm. The way I see it, your two chains can form a network representation of a discontinuous loop. And thus qualify as a single-stepper. However, I'm not a fan of DPB's representation of the network.


I am not a fan of the current trend of making networks look like chains. However, I have succumbed in my own posts of late because of the convenience of using memory to portray secondary eliminations (from networks) as part of a psudo-chain structure.

In addition, I believe that the definition of AIC should be altered to allow the initial (false) assumption to be (selectively) carried forward in its own cell(s). The following would then be an acceptable AIC "discontinuous loop" (using a lasso).

The discussion of how things should and shouldn't be represented is interesting in itself- particularly to someone, like myself, who is new to it all. However, right now I'm interested in what does or doesn't qualify as a single step. My own view, based on a similar view that Leren expressed with respect to one of my own offerings, is that any conclusions that derive from a single assumption would constitute a single step, without regard to the overall nature of the argument.

Other thoughts?

[SteveG48]

Code: Select all

 +-----------------------------------------------------------------------+
 |  16     3      45     |  46     2456   259    |  8      19     7      |
 |  16     2      57     |  8      56     579    |  19     4      3      |
 |  9      8      47     |  347    34     1      |  6      2      5      |
 |-----------------------+-----------------------+-----------------------|
 |  4      1      3      |  2      9      6      |  7      5      8      |
 |  8      5      9      |  137    13     37     |  4      6      2      |
 |  7      6      2      |  5      8      4      |  3      19     19     |
 |-----------------------+-----------------------+-----------------------|
 |  5      4      1      |  9      7      8      |  2      3      6      |
 |  3      9      8      |  146    12456  25     |  15     7      14     |
 |  2      7      6      |  134    1345   35     |  159    8      149    |
 +-----------------------------------------------------------------------+


# 44 eliminations remain

(9*)r1c6=r1c8-(9=165)r2c715-(*95=2)r1c6-(2=5)r8c6-(5=1)r8c7-(1=9)r2c7-r1c8=(9)r1c6

It took me a minute to figure out the highlighted notation as an alternate to (9=1)r2c7 - (1=6)r2c1 - (6=5)r2c5 . I like it. Is that generally accepted notation?

[DonM]

When the shared chain segment is short (two strong inferences, in this case), I don't see the merger as simpler than expressing the two chains separately.

(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=6)r2c1 - (6=5)r2c5 => r1c6<>5
(9)r1c6 = (9)r1c8 - (9=1)r2c7 - (1=5)r8c7 - (5=2)r8c6 => r1c6<>2 stte

It might allow someone to claim they solved the puzzle with a single step, as you did, but I challenge that claim as well.

Hmm. I think it qualifies as a single step. A single assumption, that r1c6 is not a 9, leads to the conclusion that it is neither a 5 nor a 2 as well, a contradiction. That seems as much a single step as the Kraken argument, which comes down to 3 parallel chains, all leading to the same conclusion and comprising all of the possibilities.

There is a major semantics problem going on here and it has to do with the term 'single-stepper'. It would seem to me that a chain that starts off with a single assumption (eg. if not (9)r1c6) and follows a straight inference path to an exclusion or exclusions by continuity or discontinuity that solves the puzzle was the original (and correct) perception of a 'single-stepper'.

However, in an unfortunate and misdirected drive for solvers to claim a 'single-stepper', chains that, by any definition, contain more than one step have been created (and perhaps even jury-rigged ) and, yet, are still called 'single-steppers'. They may be 'single-chain-solutions', but they are not single steppers. That includes pausing chains, chains using memory, nets (eg. AAICs, Kraken's this and that, etc.) and almost any chain that requires other characters (eg. *, #,-) to illustrate the logic.

Thus, the above solution may start with a single assumption, but after (9=1)r2c7, it requires two steps to place the 9 in r1c6.

But then we have Daj's rather clever chain: (9*)r1c6=r1c8-(9=165)r2c715-(*95=2)r1c6-(2=5)r8c6-(5=1)r8c7-(1=9)r2c7-r1c8=(9)r1c6. At first glance, it looks like a continuous chain, but the exclusions are via discontinuity. It also seems to act as a true 'single-stepper' -at least I don't think it's using anything that could be considered 'memory' or anything else that makes it 2 steps, but I'm not really not sure. I'd be interested to hear what Ronk thinks.

(Anticipating someone making the point that something like a single AAIC/cell or the like that solves the puzzle is a single-step: Again, that depends on what the concept of what a 'step' is. IMO, in an AAIC/Kraken net, where you are adding a strong inference to a strong inference, you are now adding a 2nd step. If that isn't true then there is going to have to be all sorts of subsets of 'single-steppers' which would be both unwieldy and misleading.)

[blue]

[ withdrawn ]

[SteveG48]

There is a major semantics problem going on here and it has to do with the term 'single-stepper'. It would seem to me that a chain that starts off with a single assumption (eg. if not (9)r1c6) and follows a straight inference path to an exclusion or exclusions by continuity or discontinuity that solves the puzzle was the original (and correct) perception of a 'single-stepper'.

Am I correct, then, in assuming that you would not consider something like a swordfish to be a single-stepper?

[Marty R.]

I can't read Don's mind, but he seems to be talking about certain types of chains. He doesn't seem to mention fish, various wings, URs and the like, which most players I know consider to be one-steppers.