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DonM

Joined: 15 Sep 2009
Posts: 51

Posted: Sun Jun 17, 2012 4:37 am Post subject:

aran wrote:

Hi Don !
One way of perserving the pattern, whilst simplifying the definition would be to extend the range in a symmetrical way (see below).
Define an SDC quite simply as a DL-ALS in which one ALS is a bivalue.
Looking for the pattern would then involve taking a bivalue and seeing whether in its box, row or column it double-links to another ALS.
In this way, the historic name remains, the scope increased, symmetry emphasised and the definition simplified.

At present SDCs :
- begin in a box (bivalue double-linking in box to second ALS)
- end in a row or column (remaining cells of second ALS).
Just complete the symmetry and include those which
- begin in a row or column
- end in a box (note if beginning in a row or column, then by virtue of the double-links, the second ALS is necessarily in a box, so no other configuration is possible)

That would, as you say, require definition of DL-ALS, but then unlike any other advanced concept, DL-ALS could be explained to a novice in 10 minutes including a coffee break !

A good point and interesting concept, but it's too late for me since I find the SDCs so easily now. Off the top of my head I can see the DL-ALS approach practical with patterns comparable to basic SDCs, but wonder if that would be true for patterns comparable to so-called extended SDCs. But that's only speculation.

aran

Joined: 19 Apr 2010
Posts: 70

Posted: Sun Jun 17, 2012 8:38 am Post subject:

DonM wrote:

it's too late for me

Well then on behalf of future generations !....

At present we have a complicated definition for a specific example (SDC) of a simple concept (DL-ALS), itself a specific example of a vast concept (Rank 0 logic).
As discussed recently HSR is another specific example of that vast concept which unlike DL-ALS cannot be simply described.

If SDC were simple to explain, this conversation would be almost pointless, but the whole point is that if the greater concept is easier to explain than the specific instance, why on earth not stay simple all the way : simple concept, simple specific example.
Indeed starting from the simple concept, the extensions to the specific example, earlier mentioned, would, I think, appear natural.

daj95376

Joined: 23 Aug 2008
Posts: 3854

Posted: Sun Jun 17, 2012 4:18 pm Post subject:

Working from the original puzzle and architech's grid after a Hidden Pair:

Code:

+--------------------------------------------------------------------------------+
| 2389 234 7 | 45689 24569 24568 | 1 a236 2368 |
| 1289 6 248 | 1489 12479 3 | 28 5 278 |
| 5 123 238 | 168 1267 2678 | 9 7-236 4 |
|--------------------------+--------------------------+--------------------------|
| 12367 123457 23456 | 3456 23456 9 | 23456 8 12367 |
| 12367 123457 23456 | 3456 8 2456 | 23456 179-236 123679 |
| 2368 9 234568 | 7 23456 1 | 23456 b236 236 |
|--------------------------+--------------------------+--------------------------|
| 4 237 9 | 1368 1367 678 | 2368 c236+1 5 |
| 367 8 356 | 2 19 567 | 36 4 e19 |
| 236 235 1 | 345689 34569 4568 | 7 d236+9 23689 |
+--------------------------------------------------------------------------------+
# 181 eliminations remain

abc e dba
(236=1)r167c8 - (1=9)r8c9 - (9=236)r961c8 => r35c8<>236

If I'm not mistaken, this is a loop ... and r9c9<>9 can be included in the eliminations.

aran

Joined: 19 Apr 2010
Posts: 70

Posted: Mon Jun 18, 2012 11:50 am Post subject:

daj95376 wrote:

Code:

+--------------------------------------------------------------------------------+
| 2389 234 7 | 45689 24569 24568 | 1 a236 2368 |
| 1289 6 248 | 1489 12479 3 | 28 5 278 |
| 5 123 238 | 168 1267 2678 | 9 7-236 4 |
|--------------------------+--------------------------+--------------------------|
| 12367 123457 23456 | 3456 23456 9 | 23456 8 12367 |
| 12367 123457 23456 | 3456 8 2456 | 23456 179-236 123679 |
| 2368 9 234568 | 7 23456 1 | 23456 b236 236 |
|--------------------------+--------------------------+--------------------------|
| 4 237 9 | 1368 1367 678 | 2368 c236+1 5 |
| 367 8 356 | 2 19 567 | 36 4 e19 |
| 236 235 1 | 345689 34569 4568 | 7 d236+9 23689 |
+--------------------------------------------------------------------------------+
(236=1)r167c8 - (1=9)r8c9 - (9=236)r961c8 => r35c8<>236

If I'm not mistaken, this is a loop ... and r9c9<>9 can be included in the eliminations.

daj
in effect all roads lead to Rome in marginally different ways, your route as shown

ronk's m-loop

SDC with DLs in c9, finishing in b6
19r8c9 and (19234567r456c79+r6c8)
ie
{19} and {19234567}
=> <2367>r5c5 <9>r9c9

ronk

Joined: 07 May 2006
Posts: 398

Posted: Mon Jun 18, 2012 1:21 pm Post subject:

aran wrote:

ronk's m-loop

To clarify, I used/use the term m-ring.

aran

Joined: 19 Apr 2010
Posts: 70

Posted: Mon Jun 18, 2012 2:43 pm Post subject:

ronk wrote:

aran wrote:

ronk's m-loop

To clarify, I used/use the term m-ring.

Since m-rings loop, and m-wings don't, the short-hand struck me as reasonable...

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