Methods for single step solutions

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Methods for single step solutions

Postby SudoQ » Fri Oct 07, 2011 7:34 am

I have created the following three puzzles with the nice puzzle generator included in the HoDoKu program.
The HoDoKu solver uses many small steps to solve these puzzles, but they can also be solved in one step.
Since I am not so familiar with standard solving techniques,
it would be interesting to see how they can be used to do this.

H1:
Code: Select all
. . . | 4 . 6 | . 2 3
. . 3 | 9 . 5 | 1 . 6
5 . . | . . . | . . .
------|-------|------
. . . | 8 . . | 2 . .
3 8 . | . . . | . 1 4
. . 5 | . . 4 | . . .
------|-------|------
. . . | . . . | . . 2
9 . 4 | 2 . 8 | 6 . .
8 7 . | 3 . 1 | . . .

H2:
Code: Select all
. . 5 | 7 . 3 | 4 . 6
. . . | 5 . . | . 7 .
. . . | . . . | . . .
------|-------|------
. 7 4 | . 2 . | . 6 5
5 . 9 | . . . | 3 . 4
3 6 . | . 4 . | 7 9 .
------|-------|------
. . . | . . . | . . .
. 9 . | . . 8 | . . .
7 . 3 | 4 . 6 | 8 . .

H3:
Code: Select all
1 . . | . 8 . | 3 . .
. . 8 | 1 . 2 | 9 4 .
. . . | 6 . . | 5 . .
------|-------|------
. . . | . . . | . . 4
. . 5 | 2 . 4 | 1 . .
9 . . | . . . | . . .
------|-------|------
. . 1 | . . 3 | . . .
. 3 2 | 5 . 8 | 4 . .
. . 7 | . 6 . | . . 8

/SudoQ
SudoQ
 
Posts: 39
Joined: 09 September 2011

Re: Methods for single step solutions

Postby daj95376 » Fri Oct 07, 2011 12:27 pm

Not sure what you want. However, here's a single-stepper chain for H1 incorporating ALS.

Code: Select all
 H1: after basics
 +-----------------------------------------------------------------------+
 |  17     19     1789   |  4      178    6      |  5      2      3      |
 |  247    24     3      |  9      278    5      |  1      478    6      |
 |  5      1246   1678   |  17     12378  237    |  4789   4789   789    |
 |-----------------------+-----------------------+-----------------------|
 |  1467   1469   1679   |  8      1379   37     |  2      35679  579    |
 |  3      8      679    |  567    2579   27     |  79     1      4      |
 |  1267   1269   5      |  167    1379   4      |  3789   36789  789    |
 |-----------------------+-----------------------+-----------------------|
 |  16     35     16     |  57     4      9      |  378    378    2      |
 |  9      35     4      |  2      57     8      |  6      37     1      |
 |  8      7      2      |  3      6      1      |  49     459    59     |
 +-----------------------------------------------------------------------+
 # 98 eliminations remain

 (7)r1c13 = r1c5 - r8c5 = r7c4 - (17=6)r36c4 - r5c4 = r5c3 - (6=1789)r3c3,r1c123  =>  r2c1<>7

Less complex alternative:

Code: Select all
 (6)r3c2 = r3c3 - r5c3 = (6-5)r5c4 = (5-7)r7c4 = r8c5 - r1c5 = r1c13 - (7=24)r2c12  =>  r3c2<>24
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Re: Methods for single step solutions

Postby SudoQ » Fri Oct 07, 2011 12:59 pm

daj95376 wrote:Not sure what you want.

Yes, that's what I wanted. Thanks!

Now I will try to understand your formula.
Do you know where I can find a 'Sudoku syntax for dummies' !?

/SudoQ
SudoQ
 
Posts: 39
Joined: 09 September 2011

Re: Methods for single step solutions

Postby daj95376 » Fri Oct 07, 2011 4:44 pm

SudoQ wrote:Do you know where I can find a 'Sudoku syntax for dummies' !?

A good starting place.

From my notes:

Code: Select all
===== ===== =====   Basic Chain Terminology and Eureka Notation   ===== ===== =====


Strong Inference (SI):  ~A =>  B
Weak   Inference (WI):   A => ~B


(SI)  e.g.: (   bilocation  (n)a = (n)b   ) or (   bivalue cell  (m=n)c   )
(WI)  e.g.: (   peers       (n)d - (n)e   ) or (   ?-value cell  (m-n)f   )


bilocation   (n)a = (n)b:  if [a] is not 'n', then [b] is     'n'
bivalue cell    (m=n)c  :  if [c] is not 'm', then [c] is     'n'

peers        (n)d - (n)e:  if [d] is     'n', then [e] is not 'n'
?-value cell    (m-n)f  :  if [f] is     'm', then [f] is not 'n'


Myth Jellies' Alternating Inference Chain (AIC):  ( SI WI )*  SI
   -- if the endpoints are the same cell & candidate,  a discontinuous AIC loop
   -- if a WI can connect  the same cell & candidate,  a    continuous AIC loop

The tilda (~) means logical-NOT.

The asterisk (*) indicates possible multiple occurrences (in the AIC description).

Note #1: When it comes to embedded structures -- like ALS, URs, etc. -- personal preference leads to differing notation.

Note #2: When it comes to networks, the notation again varies by personal preference.
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