## BUG help

Advanced methods and approaches for solving Sudoku puzzles

### BUG help

I've read the plain English instruction of the BUG.
Sorry I'm so dumb but I got an error when I typed the answer
into Brain Basher Sudoko.

I have a row:

9 1 2 345 8 7 45 6 35

I thought according to the BUG instructions, that the 345 would = 5
because:

- there is one cell with three numbers
- there are two cells with two numbers
- "5" is the number that is repeated three times in this row

Yet, when I type in a 5 in the 345 cell on the Sudoko Brain Bashers site,
it shows 5 as being an error.

What am I not understanding???

Thanks so much!
Chris
uturn

Posts: 3
Joined: 07 June 2006

In its simple form, the BUG rule states that, if we have a grid in which all but one the undecided cells have just two possible candidates, and the other cell have three possible candidates, then the candidate in this cell that appears three times in its row, column, and box is the correct one for that cell. In your example, the "5" seems to appear three times only in its row.

Carcul
Carcul

Posts: 724
Joined: 04 November 2005

So in your above example, in order to be a BUG or BUG-lite the grid would need to look something like:
Code: Select all
`------|---------|--------9 1 2 | 345 8 7 | 45 6 35 8 7 6 | 34  9 1 | 45 2 35 ------|---------|--------`

where the big numbers are arbitrary, but the 3, 4, 5 occur twice in the columns, rows and boxes except where the elimination occurs for a BUG+1. Many other kinds of BUG eliminations are possible. See
Mike Barker

Posts: 458
Joined: 22 January 2006

### BUG help and Carcul's reply

Carcul replied that the 5 is the only number appearing three times,
and thus the 345 = 5. However, this is WRONG, as I've typed a 5
into this cell and Brain Bashers shows 5 as being an error for this cell.

And that's my problem. I also thought that, according to my understanding of BUG, 345 would = 5. But it doesn't. So, anyone
who can please enlighten me, I would greatly appreciate understanding
this BUG row:

9 1 2 345 8 7 45 6 35

All single digit cells have been confirmed as correct.
uturn

Posts: 3
Joined: 07 June 2006

Uturn, it would be much more easy for us to help, if you post the complete grid that you are talking about.

Carcul
Carcul

Posts: 724
Joined: 04 November 2005

The problem is that you are only looking at one row. I think that is what Carcul was refering to in his post.

To use any BUG rules you need at least two units (boxes, rows, and/or columns). Because the rule works off of there being a unique solution, It must operate on a setup that can possibly affect the uniqueness(or existence) of the solution.

So if your grid was setup as Mike put, elimination of 5 at the 345 cell would leave 2 possible solutions.

Hope that helps(I hope I got it correct!).
doduff

Posts: 32
Joined: 29 May 2006

### BUG help and Carcul's reply and Here's the whole puzzle

Apologies to all.

Here is the entire puzzle. I have confirmed that all single digits numbers
are correct.

I thought (from Tso's plain English explanation of BUG) that
345 (r1,c4) would be = 5. But it shows an error when I type 5 in that
cell (on the Brain Bashers website). What am I not understanding

9 1 2 345 8 7 45 6 35
5 _ _ 9 6 1 _ _ 2
_ _ 8 _ _ 2 9 _ _

_ 9 _ 1 2 4 _ 3 _
_ 2 _ _ 9 _ _ 4 _
_ 8 _ 7 3 5 _ 2 9

2 _ 1 _ _ _ 3 _ _
8 5 _ 2 7 3 _ _ 4
_ 4 _ _ 1 _ 2 5 _

Thanks again to all!
UTURN
uturn

Posts: 3
Joined: 07 June 2006

Uturn, you cannot apply the BUG rule because you have a lot of undecided cells with more than 2 candidates. Please read carefully what I have written in my first reply: you can only apply the BUG (in its simplest form) to a candidate in a cell that occurs three times in its row, column, and box.
However, the puzzle can be easily solved with one of the Unique Rectangles present in it.

Carcul
Carcul

Posts: 724
Joined: 04 November 2005

### Re: BUG help

uturn wrote:What am I not understanding???

I'll try... You need to look at every single unsolved cell of the entire sudokuboard It is not enough to look at just one row. If your whole board was just cells with two candidates in them exept for one cell, then you could maybe apply the bug rule. NOT otherwise!

Havard
Havard

Posts: 377
Joined: 25 December 2005