The New Sudoku Players' Forum

[Kent]

Can someone explain this please?? I dont understand the symbols.Thanks


r8c7]{=(AUR:r1c7/r1c8/r8c7/r8c8)=3|4=[r1c8]-4-[r1c1]=4=[r7c1]-4-[r9c2]}=3=[r5c7](=8=[r4c7]-8-[r4c6])-3-[r5c5](-2-[r4c6]-6-[r8c6])-2-[r1c5](-3-[r3c6]-2-[r8c6])-3-[r1c1]=3=[r3c1]=8=[r3c2]-8-[r9c2]-6-[r9c4]-3-[r8c6],

[Kent]

i still dont get the ALZ part.The website doesnt explain much.I need some basics about ALZ.Thanks

[Carcul]

Hi Kent.

See this link for an explanation of the notation, and this link for a thread about Almost Unique Rectangles (AUR).

Regards, Carcul

[tso]

Carcul,

I think it's *very* difficult for someone to figure out this notation given only the link you gave. The information is spread out throughout several pages and not labed as "NOTATION". The more complicated usages that you make are explained nowhere. If there isn't a short page in the forum that spells out this notation, perhaps you could create one -- I cannot as I'm *still* not fluent with all of it.

[r8c7]{=(AUR:r1c7/r1c8/r8c7/r8c8)=3|4=[r1c8]-4-[r1c1]=4=[r7c1]-4-[r9c2]}=3=[r5c7](=8=[r4c7]-8-[r4c6])-3-[r5c5](-2-[r4c6]-6-[r8c6])-2-[r1c5](-3-[r3c6]-2-[r8c6])-3-[r1c1]=3=[r3c1]=8=[r3c2]-8-[r9c2]-6-[r9c4]-3-[r8c6],


My best attempt at some of the notation:



"[r1c1]" -- the cell at row one, column one

"[r1c8]-4-[r1c1]" -- the two cells are "weakly linked" by the candidate '4'. Only one of these two cells can be 4. It is possible that neither is 4, but not both.

"[r1c1]=3=[r3c1]" -- the two cells are "stongly linked" by the candidate '3'. Exactly one of these two cells must be 3.

"AUR:r1c7/r1c8/r8c7/r8c8" -- These four cells form an Almost Unique Rectangle. Either r8c7 must be 3 OR r1c8 must be 4 (or both) -- otherwise the puzzle would have two solutions.

"[r8c7]{=(AUR:r1c7/r1c8/r8c7/r8c8)=3|4=[r1c8]" -- I'm not sure if I understand this usage exactly or if it is the usage that is flawed. It *seems* to say that [r8c7] is strongly linked (by way of an AUR) to [r1c8] by 3|4 -- that is, either r8c7=3 is true or r1c8=4 is true, BUT NOT BOTH.

Unfortunately, BOTH CAN be true.

Isn't "[r8c7]-(<>56)-[r1c8]" more accurate than"[r8c7]=3|4=[r1c8]"? Either r8c7<>56 OR r1c8<>56 OR both.

"(<>56)" -- "does not equal 5 or 6"


I cannot explain nor fully understand the placement and usage of the paranthesis and braces.

"[r5c7](=8=[r4c7]-8-[r4c6])" -- I don't understand why the opening paranthesis is before =8= instead of after or how to interpret it in english or draw it on a diagram -- and I certainly cannot look at the constuction on the screen and see the conclusion.

Maybe Carcul could translate?

In fact, maybe Carul could translate this entire construction in verbose detail so that we could be pointed to that page in the future?

[Carcul]

Hi Tso.

If there isn't a short page in the forum that spells out this notation, perhaps you could create one

Good idea. I will try to work on that in the next days.

It *seems* to say that [r8c7] is strongly linked (by way of an AUR) to [r1c8] by 3|4 -- that is, either r8c7=3 is true or r1c8=4 is true, BUT NOT BOTH.

Unfortunately, BOTH CAN be true.

Yes, both can be true, but the meaning of [r8c7]=3|4=[r1c8] (which is explained in the AUR thread) is simply the following: if r8c7 is not "3" then r1c8 must be "4", conversely, if r1c8 is not "4" then r8c7 must be "3". The link doesn't exclude the case r8c7=3 and r1c8=4, it only tell us what must happen if r8c7<>3 or r1c8<>4.

Regards, Carcul

[Cec]

"Hi Tso.
...Yes, both can be true, but the meaning of [r8c7]=3|4=[r1c8] (which is explained in the AUR thread) is simply the following: if r8c7 is not "3" then r1c8 must be "4", conversely, if r1c8 is not "4" then r8c7 must be "3". The link doesn't exclude the case r8c7=3 and r1c8=4, it only tell us what must happen if r8c7<>3 or r1c8<>4".

Advanced techniques like this are still difficult for me to follow and reading the following quote from part of tso's above post - and whose sudoku knowledge and ability to clearly explain techniques I greatly respect - at least makes me feel my shortcomings are easier for me to accept.

"Carcul,
...I'm *still* not fluent with all of it...."

When reading Carcul's above reference to the AUR thread that the meaning of [r8c7]=3|4=[r1c8] is simply "if r8c7 is not "3" then r1c8 must be "4", then I would prefer to see the first = sign replaced by a different symbol which better explains the meaning "is not" - I'm assuming of course there is no "defined" alternative at present. A suggested alternative could be this || or this // and I guess the point I'm trying to make is that anything would be better than an = sign!

Cec