## Desperate for help!

Advanced methods and approaches for solving Sudoku puzzles

### Desperate for help!

I'm pretty new to Sudoku. I've managed to do some graded "Hard" in the local paper (they're Pappocom) but I'm absolutely stuck on this "Medium":

*** *5* *9*
3** *** **6
**4 82* 57*

2** 6** 7**
*** 5*1 ***
**7 **3 **8

*38 *65 2**
7** *** **5
*5* *9* ***

Which I've worked out to:

*** 35* *9*
3*5 91* **6
**4 826 573

2*3 689 75*
*** 571 ***
5*7 243 **8

*38 *65 2**
7** *3* **5
*5* *9* ***

I've read about "fishes", "chains" and "wings" on this website but it's all beyond me at the moment. I'm not interested in trial and error. Is there anyone generous enough to give me a hint about how to proceed and thereby save my sanity? Thank you.
tom375

Posts: 5
Joined: 21 July 2005

### Re: Desperate for help!

tom375 wrote:I've read about "fishes", "chains" and "wings" ...

You dont need them for this. Look where the 1's can be in box 4, it will help you for box 1.
Wolfgang

Posts: 208
Joined: 22 June 2005

1. The value 1 in Box [1,1] must lie in Row 3.
The value 1 in Box [3,1] must lie in Column 3.
The cell (3,1) is the only candidate for the value 1 in Column 1.

Regards

http://daily-sudoku.tk
chabo

Posts: 5
Joined: 23 July 2005

### Thanks

To Wolfgang and Chabo

Thank you very much for your help. Tom375
tom375

Posts: 5
Joined: 21 July 2005

### Desperate for help!

chabo wrote 1.The value in Box[1,1] must lie in row 3.
The value 1 in Box[3,1] must lie in column 3
The cell[3,1] is the only candidate for the value 1 in column 1.

No offence Chabo but I find it hard to follow your above post which departs from the recommended "Basic terms" suggested by Pappocom www.sudoku.com/boards/viewtopic.php?t=2
Boxes are numbered 1 to 9 as follows:
123
456
789
What does Box [1,1] mean?
I think you mean the 1 in Box 3 must lie in column 7 not column 3

Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

### Desperate for help!

Oops! Sorry chabo I misquoted you . I meant to type "The value 1 in Box [1,1] must lie in Row 3.
Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

To clear some things up:

Box[1, 1] is box 1. (first band, first stack)
Box[2, 3] would be box 6.
(Box[3, 1] is box 7.)

Does this explain it?
Animator

Posts: 469
Joined: 08 April 2005

### Desperate for help!

Animator wrote: To clear some things up:

Box[1,1] is box 1. (first band, first stack)
Box[2,3] would be box 6.
(Box[3,1] is box 7.)

Does this explain it?

Whilst I've finally worked out what you mean, your description also doesn't follow Pappocom's recommended "Basic terms". There are nine boxes in the puzzle grid with each box containing nine cells. Three horizontal adjoining boxes is a band whilst three vertical adjoining boxes is a stack. Pappocom's suggested "Basic terms" makes it easier for readers to follow if cells are referenced by their row and column number, not their box number. Your reference to Box[1,1] is presumably cell r1c1.

Frankly, as a "newbie" it becomes confusing - and I suspect also "oldies" - to understand that "Box [2,3] would be box 6" and "Box[3,1] is box 7".

I hope I've cleared it up!

Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

A reference to Box[1,1] is a reference to Box 1. Else it would be written as r1c1 or as [1, 1]. But never Box[1, 1].

Also, from what I can see it follows the recommended 'Basic Terms'. It might not be entirely clear though, but that's a different matter.

A grid has three bands, let's call them first band, second band and third band.

The first band consists of the row 1, 2 and 3.

A grid also has three stacks. The first one consists on column 1, column 2, and column 3.

If you look at the intersection of the first band with the first stack then you find Box[1, 1], which is box 1.
Animator

Posts: 469
Joined: 08 April 2005

### Desperate for help!

It seems Animator is now agreeing that any reference to Box 1 should not be written as Box[1, 1] which precisely is the point I raised in my previous reply of Tue July 26. Any reference to Box 1 should only mention Box1 and not Box[1, 1] which you again mention, presumably as an oversight, in the last para.of your latest post of July 26.

I might add that Pappocom's recommended "Basic terms" suggests the three bands be called top (ie rows 1,2 and 3) middle (rows 4,5 and 6) and bottom (rows 7,8 and 9) rather than first, second and third bands and that the three stacks be called left (ie columns 1,2 and 3) middle (columns 4,5 and 6) and right (columns 7,8 and 9).

Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

### Terminology

Whilst I agree that some of the terminology isn't exactly self explanatory to newbies (and some oldies!) - 'disjoint subsets' being an example! - I fully agree. At this stage in the evolution of solving techniques it will only be damaging to start messing around with nomenclature - by all means call boxes what you want --- but please don't try to influence others to follow your line - It'll only make the whole thing more confusing to new initiates and make life more difficult for those trying to give advice.

Rant over

Gin required

www.brightonandhove.org/sudoku/solver5c.xls
stuartn

Posts: 211
Joined: 18 June 2005

### Desperate for help!

Thanks stuartn for your comments and some points taken. It was never my intention to influence others to "follow my line" but rather to follow the suggested terminology of Pappocom's "Basic terms" so that confusion can be avoided such as initiates who read "[Box2,3} would be box 6 and Box{3,1] is box 7".
Thanks again for your thoughts. Matter now closed and I'll have that gin.
Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005

### Re: Desperate for help!

tom375 wrote:I'm pretty new to Sudoku. I've managed to do some graded "Hard" in the local paper (they're Pappocom) but I'm absolutely stuck on this "Medium":

*** *5* *9*
3** *** **6
**4 82* 57*

2** 6** 7**
*** 5*1 ***
**7 **3 **8

*38 *65 2**
7** *** **5
*5* *9* ***

Which I've worked out to:

*** 35* *9*
3*5 91* **6
**4 826 573

2*3 689 75*
*** 571 ***
5*7 243 **8

*38 *65 2**
7** *3* **5
*5* *9* ***

I've read about "fishes", "chains" and "wings" on this website but it's all beyond me at the moment. I'm not interested in trial and error. Is there anyone generous enough to give me a hint about how to proceed and thereby save my sanity? Thank you.

OK, here are the steps. First label the rows down 1,2,3,4,5,6,7,8,9 and the columns accross A,B,C,D,E,F,G,H,I.
STEPS:
E6=4
E4=8
E5=7
F4=9
D6=2
F3=6
C2=5 (BLOCK CAN ONLY BE 5)
A6=5 (BLOCK CAN ONLY BE 5)
E2=1
E8=3
D2=9
D1=3
I3=3
H4=5
C4=3
B3=9 (SINCE BLOCK A4:C6 CAN ONLY HAVE #1 IN COLUMN B, THERE CAN'T BE ANY OTHER 1's IN COLUMN B)

A3=1
G6=9 (sINCE B6 & H6 MUST BE 1 OR 6, THEN G6 CAN'T BE A 1 OR 6, SO ONLY NUMNER REMAINING FOR G6 IS 9)

I7=9
A7=4
A9=6
A1=8
A5=9
C5=6
B6=1
B4=4
B5=8
B8=2
C9=1
C8=9
C1=2
B2=7
B1=6
F2=4
F1=7
G2=8
I4=1
H2=2
I1=4
G1=1
F8=8
F9=2
I5=2
H6=6
H7=1
H8=4
H5=3
I9=7
G5=4
G8=6
G9=3
H9=8
D7=7
D8=1
D9=4
COMPLETE
dick

Posts: 3
Joined: 21 July 2005

### dick

Dick - in light of the above messages, is this really helpful? - consider that the sages of this august organ use RnCn as their accepted naming strategy - and these people are of immense assistance to all the newbies out there - can 'telling' somebody to use an alternative strategy really be helpful? - perhaps you could edit your 'helpful' reply to use a nomenclature that is common to all board users?

stuartn

www.brightonandhove.org
stuartn

Posts: 211
Joined: 18 June 2005

### Desperate for help!

Stuartn wrote in reply to Dick "In light of the above messages...........perhaps you could edit your "helpful" reply to use a nomenclature that is common to all board users".

Although I recently chose to end this "rant" as suggested by stuartn, the above post has prompted me to respond to appease my dilemma.

The main purpose of my initial post suggested members use Pappocom's recommended "Basic terms" for consistency in helping me, and presumably others, to better understand members' posts on puzzle solving. For this I was criticised as per the above post of Tue July 26.

The latest criticism suggesting Dick " to use a nomenclature that is common to all board users- and which I agree - seems to now endorse my initial similar message (July 26) for which I was criticised. Hopefully my dilemma means I've received an elephant stamp!

Regards Bonsai Cec
Cec

Posts: 1039
Joined: 16 June 2005