## Hidden rectangles: old hat revisited

Advanced methods and approaches for solving Sudoku puzzles

### Hidden rectangles: old hat revisited

http://www.sudokuwiki.org/Hidden_Unique_Rectangles
types 1,2 are found there

A third type of hidden unique rectangle is plausible:
Code: Select all
` *---------------------------* |A-B .   AB | . . . | . . . | |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | |-----------+-------+-------| |/   .    . | . . . | . . . | |AB+ \  -AB+| \ \ \ | \ \ \ | |/   .   .  | . . . | . . . | |-----------+-------+-------| |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | *---------------------------*`

where AB+ = a cell with extra candidates
\ = no candidates for B
/ = no candidates for A

R1C1 <> B
R5C3 <> A,B

A 4th type of hidden unique rectangle is plausible:

Code: Select all
` *---------------------------* |A+-B .  AB | . . . | . . . | |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | |-----------+-------+-------| |/   .    . | . . . | . . . | |AB+ \  B-A+| \ \ \ | \ \ \ | |/   .   .  | . . . | . . . | |-----------+-------+-------| |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | |/   .    . | . . . | . . . | *---------------------------*`

where AB+ = a cell with extra candidates
\ = no candidates for B
/ = no candidates for A

R1C1 <> B
R5C3 <> A
Last edited by StrmCkr on Wed Oct 20, 2010 6:01 am, edited 2 times in total.
Some do, some teach, the rest look it up.

StrmCkr

Posts: 862
Joined: 05 September 2006

### Re: Hidden rectangles: new tricks? or old hat

UR:s like this have been explored here.

RW

PS. I think your first example should say r1c1 <> B.
RW
2010 Supporter

Posts: 1000
Joined: 16 March 2006

### Re: Hidden rectangles: new tricks? or old hat

thanks RW i was pretty sure i read about these a long time ago...

but now that im programing ur types into my solver i figured id post and see what kind of attention and maybe the directed to the older posts on the topic.

I went back and fixed the grid earlier .... i guess i missed the explanation below thanks again.

I'll have a look at the thread and see what else i can build into my solver with these

{ I am having some difficulties understanding what is written in that linked post }

{its more then likely going to take me some time to sort out mikes post... }

{ i have Urs type 1,2,4,5,6 as defined here
hidden rectangles types 1,2 + the ones above} ... looks like i have some more work ahead of me to bring that up to date..
Some do, some teach, the rest look it up.

StrmCkr

Posts: 862
Joined: 05 September 2006