DonM,
Very good, but where's the better example?
denis_berthier wrote:You're saying SdC "may" be more frequent than it seems. If you want to raise interest in it, it's your job to prove this or at least to give a more convincing example.
Luke451 wrote:I love my computer, but when I do a puzzle I sharpen a pencil.
denis_berthier wrote:Luke451 wrote:I love my computer, but when I do a puzzle I sharpen a pencil.
I wasn't critcising SdC but only DonM's understated claims on frequency - and I don't yet take them for granted, even after Ruud's list (see my answer in the other thread).
DonM wrote:But for the 3 in r4c1, the basic Sue De Coq pattern is present: the core blue cells (an aals with 1,5,6,7,9 in 3 cells), the brown cell A with 5,7 and the green cell C with 1,9. The logic is straightforward: If not 3 in r4c1 then the Sue De Coq is true and any of the circled green cells are valid weak link ‘targets’. In this case a relatively simple chain eliminates the 9 in r4c1:
aic:
(3)r4c1 = suedecoq[(15679)r4c123/r4c5(19)/r5c3(57)] - (6)r4c7 = r6c7-(6=8)r6c3 - (8=9)r4c2 => r4c1<>9
nice loop:
r4c1 -9- r4c1 =3= suedecoq[(15679)r4c123/r4c5(19)/r5c3(57)] -6- r4c7 =6= r6c7 -6- r6c3 -8- r5c2 -9- r4c1 => r4c1<>9
ronk wrote:DonM wrote:But for the 3 in r4c1, the basic Sue De Coq pattern is present: the core blue cells (an aals with 1,5,6,7,9 in 3 cells), the brown cell A with 5,7 and the green cell C with 1,9. The logic is straightforward: If not 3 in r4c1 then the Sue De Coq is true and any of the circled green cells are valid weak link ‘targets’. In this case a relatively simple chain eliminates the 9 in r4c1:
aic:
(3)r4c1 = suedecoq[(15679)r4c123/r4c5(19)/r5c3(57)] - (6)r4c7 = r6c7-(6=8)r6c3 - (8=9)r4c2 => r4c1<>9
nice loop:
r4c1 -9- r4c1 =3= suedecoq[(15679)r4c123/r4c5(19)/r5c3(57)] -6- r4c7 =6= r6c7 -6- r6c3 -8- r5c2 -9- r4c1 => r4c1<>9
When the elimination of a Sue de Coq ("SdC") pattern is in the SdC pattern itself, even an almost SdC pattern, IMO it's a safe bet that there will always be a smaller pattern. Using all but two of those same cells, we have a simpler chain ...
r4c1 -9- als:r4c25 -5- als:[r456c3,r5c2] -9- r4c1 ==> r4c1<>9
... also known as the ALS xz-rule. However, the almost SdC is still an interesting POV.
Luke451 wrote:- The reason [3 = The SdC] is because either the 3 is true or the SdC is true.
- This means that [3 = The SdC] can be used as a strong link in an AIC or Nice Loop.
- The green circled candidates represent possible targets for weak links to follow after [3 = The SdC].
- The loop begins and ends with a weak discontinuity on 9, so r4c1<>9.
Have I the basics right?
Why's the 6 in r6c1 green circled and not the 9? Or the 9 in r4c9 and not the 5 or 7 in r4 box 6?
Can the "extra candidate" also be in cells a or b?
My reality check: Finding a naked Sue de Coq is always cool, but not that easy. An "almost" is tougher, albeit perhaps more common. Finding a useful loop off an "almost" ups the ante once again into the "are you kidding me" range. I guess only time/practice will tell. That said, thanks to Don for your great effort here. I've learned a lot, and thanks to ronk, hobiwan, Glyn and others for pointing out useful variations and nuance.