## Impossible puzzle

Post the puzzle or solving technique that's causing you trouble and someone will help

### Impossible puzzle

Some games are easy, others hard. The question is, are there any impossible games?

The constraint is that all values preset in the sudoku problem itself must be legal – that is integers from 1 through 9, and no repeats in rows, columns, or in the 3X3 boxes.

If you think that impossible puzzle, could you give me an example?
arvindcr

Posts: 1
Joined: 23 May 2006

### Re: Impossible puzzle

arvindcr wrote:Some games are easy, others hard. The question is, are there any impossible games?

The constraint is that all values preset in the sudoku problem itself must be legal – that is integers from 1 through 9, and no repeats in rows, columns, or in the 3X3 boxes.

If you think that impossible puzzle, could you give me an example?

Sure. Here's one with no solutions:

Code: Select all
` *-----------* |.3.|18.|.9.| |..6|..9|..1| |21.|...|...| |---+---+---| |...|..6|.7.| |9.7|.2.|6.8| |.8.|7..|...| |---+---+---| |...|...|.29| |1..|2..|4..| |.7.|.45|.3.| *-----------*`

Here's an invalid puzzle with multilple solutions:

Code: Select all
` *-----------* |.3.|1..|...| |..6|...|..1| |21.|...|...| |---+---+---| |...|..6|.7.| |9.7|.2.|6.8| |.8.|7..|...| |---+---+---| |...|...|.29| |1..|2..|4..| |.7.|.45|.3.| *-----------*`

Here's a valid puzzle with a unique solution:

Code: Select all
` *-----------* |.3.|18.|.6.| |..6|..9|..1| |21.|...|...| |---+---+---| |...|..6|.7.| |9.7|.2.|6.8| |.8.|7..|...| |---+---+---| |...|...|.29| |1..|2..|4..| |.7.|.45|.3.| *-----------*`
Sped

Posts: 126
Joined: 26 March 2006

No-solution puzzles are easy to construct:

This puzzle is impossible to complete, as there is nowhere in box one to place a 1.

Code: Select all
`. . . | 1 . . | . . . . . . | . . . | 1 . . . . 2 | . . . | . . . ------+-------+------1 . . | . . . | . . . . . . | . . . | . . . . . . | . . . | . . . ------+-------+------. 1 . | . . . | . . . . . . | . . . | . . . . . . | . . . | . . . `
tso

Posts: 798
Joined: 22 June 2005