## Triple confusion

Advanced methods and approaches for solving Sudoku puzzles

### Triple confusion

3**|*2*|*41
**1|4*3|728
42*|**1|**5
-----------
7*3|**5|*19
15*|***|*6*
2**|1**|5**
-----------
83*|61*|***
*74|3*2|1*6
61*|*9*|**3

Hidden triples.
Can a triple be identified by inspection when there is more than one possibility?

In row 1 the triple is col 4-78, col 7-678, col 8-678, not the 479 combination.
In row 3 the triple is col 1-37, col 4-378 and col 7-78, not the 479 combination.
In column 2 the triple is row 5-235, row 7-25, row 9-235, not the 125 combination.

If this has been covered before please direct me.
Weesleekit2
weesleekit2

Posts: 5
Joined: 04 October 2005

Just a general answer: not having seen the specific pencilmarks in your puzzle: You can have more than one set of triples in a puzzle, each can stand on its own to make exclusions in the unit involved (row, column or box). This is when, as in your example, discrete units are involved.

(You can also have a pair of triples in one unit, one of those naked, the other hidden. In that case, they result in identical exclusions. You can also, often, have a pair of naked triples in one unit, this is trivial since no exclusions generally result.)
Doyle

Posts: 61
Joined: 11 July 2005

Hi, weesleekit2,

You said
In row 1 the triple is col 4-78, col 7-678, col 8-678, not the 479 combination

Sorry I am a bit slow. Here are the pencilmarks for row 1 (that I compute):

Col 1 - Solved
Col 2 - 689
Col 3 - 56789
Col 4 - 5789 < 78 (Yes, I see this)
Col 5 - Solved
Col 6 - 6789
Col 7 - 69 < 678 ????
Col 8 - Solved < 678 ????
Col 9 - Solved

What am I missing here?

Mac
QBasicMac

Posts: 441
Joined: 13 July 2005

weesleekit2

The possible triplets you mention do not correspond with the grid you posted, see Mac above for one example.

Hidden triplets can be found if they exsist, but may be difficult to spot.
MCC

Posts: 1275
Joined: 08 June 2005

### Apologies

I am sorry..... I punched in the wrong numbers. If there is a way to remove this post it should be scratched. I will post my question again.
Sorry
weesleekit2

Posts: 5
Joined: 04 October 2005

### Delete request

Apparantly I can't delete it because it has been answered. I hope the administrators will delete it quickly so no one else tries to make sense out of it.
weesleekit2

Posts: 5
Joined: 04 October 2005

Just post the correct puzzle. Anyone will easily get past the preamble.

Mac
QBasicMac

Posts: 441
Joined: 13 July 2005