David P Bird wrote:I've been told before that my posts are difficult to understand so I'm sorry you haven't been able to follow me so far in this thread.

Oh, i am rather happy with what i

could follow. Looking at this post i have the feeling, that i understood more of your patterns than you know about the others.

I know the basic SdC pattern but I don't know it stops being a SdC when it gets extended. I therefore avoid the term.

... and replace it by MSNS. This does it for you, but not for me, who is not interested to learn things twice, which are probably the same.

Doubly Linked ALSs seem to cover most if not all of the various possibilities but I'm no expert on them and don't know if they are always contained in a single band of boxes.

Yes, that's what i also (don't) know about them.

However they cover a particular type of rank 0 pattern that can be represented by Multi-Sector Locked Sets.

I have to admit, that i did not know, what rank 0 means, until aran wrote "rank = base-cover". So i did not miss much. Both a single and any grid are rank 0 patterns, and some sets between, fine.

These patterns can be expressed as truth and link sets – also known as base and cover sets.

So MSLS and base/cover are the same. Nice to know.

They may also be translatable into AIC loops (when no digit will appear in more than two consecutive links).

Ah yes, AIC's only see black or white.

As the basic SdC occupies one box and one line it is therefore a 2-sector naked set.

This does not change with the extensions described in the hodoku doc. So now i think, that 2SNS and SDC are simply the same. SDC sees it as 3 sets, 2SNS as two ?

[Edit:]This is probably a misunderstanding, because i guess that 2 sectors also can be 2 (parallel) lines. So now i see both DL-ALS and SDC's as subsets of 2SNS and conversely i don't believe, that there are other 2SNS, which are not covered by DL-ALS and SDC, so that we would have 2SNS=DL-ALS+SDC. Unfortunateley i will not get a confirmation by the experts, because the one does not know, what the other does.

In this thread I've shown that the locked sets concerned can either be naked or hidden built up from overlapping (or intersecting) ANSs or AHS respectively in each sector.

For overlapping ANSs a hit happens when one of the digits that may be false in one ANS must be true in the other.

For overlapping AHSs a hit happens when one of the digits that isn't locked in one AHS is locked in the other.

I

had got that.

Overlapping ANSs and AHSs can occur alone or both together

So you confirm, that here are MSHS with no MSNS equivalent and vice versa. However, examples would be fine.

There are therefore 4 ways to find these patterns

a) look for a known SdC pattern

b) look for a doubly linked ANS loop

c) look for overlapping ANSs or AHSs that combine to give a MSLS

d) use a base and cover set approach

a)-c) are base and cover set approachs too, are'nt they ?