Hello again
I've had some advice on doing 'fiendish' (in The Times) level puzzles. Crazy Girl etc said that the most difficult aspect of these would be a hidden pair.
Why can't I see one in this puzzle??
* 7 9 | * * * | 2 * *
* * * | 2 * 1 | * * *
6 8 4 | * 2 7 | * 3 1
7 2 1 | * * 3 |6 4 *
3 9 5 | 4 1 6 | 7 8 2
9 5 * | * 4 * | * * *
* * * | 3 * 9 | * **
* * 6 | * * * | 4 9 *
Thanks for any help
Mark
Hidden pairs?
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by markb » Thu Jan 19, 2006 7:45 pm
Maybe that's why it's so difficult!
Sorry, should have been -
* 7 9 | * * * | 2 * *
* * * | 2 * 1 | * * *
* * * | * 3 * | * 5 *
6 8 4 | * 2 7 | * 3 1
7 2 1 | * * 3 |6 4 *
3 9 5 | 4 1 6 | 7 8 2
9 5 * | * 4 * | * * *
* * * | 3 * 9 | * **
* * 6 | * * * | 4 9 *
Cheers
Mark
Sorry, should have been -
* 7 9 | * * * | 2 * *
* * * | 2 * 1 | * * *
* * * | * 3 * | * 5 *
6 8 4 | * 2 7 | * 3 1
7 2 1 | * * 3 |6 4 *
3 9 5 | 4 1 6 | 7 8 2
9 5 * | * 4 * | * * *
* * * | 3 * 9 | * **
* * 6 | * * * | 4 9 *
Cheers
Mark
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- Joined: 27 December 2005
by Carcul » Thu Jan 19, 2006 8:34 pm
Hi Markb.
It's a naked quad: four cells populated only with the same four candidates (but not necessarily with all those four candidates in each of the four cells). In box 2 you have cells r1c4,r1c5,r1c6,r3c6 populated just with the numbers 4,5,6,8: therefore, these candidates can be eliminated from r2c5 and r3c4.
Hope this help.
Regards, Carcul
It's a naked quad: four cells populated only with the same four candidates (but not necessarily with all those four candidates in each of the four cells). In box 2 you have cells r1c4,r1c5,r1c6,r3c6 populated just with the numbers 4,5,6,8: therefore, these candidates can be eliminated from r2c5 and r3c4.
Hope this help.
Regards, Carcul
Last edited by Carcul on Thu Jan 19, 2006 4:35 pm, edited 1 time in total.
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by markb » Thu Jan 19, 2006 8:43 pm
Sorry I meant naked quad.
It's a naked quad: four cells populated only with the same four candidates (but not necessarily with all those four candidates in each of the four cells). In box 2 you have cells r1c4,r1c5,r1c6,r3c6 populated just with the numbers 4,5,6,8: therefore, these candidates can be eliminated from r2c5 and r3c4
But 5, 6 & 8 are in r2 c5 AND 4 & 8 are in r3 c6
???
Mark
It's a naked quad: four cells populated only with the same four candidates (but not necessarily with all those four candidates in each of the four cells). In box 2 you have cells r1c4,r1c5,r1c6,r3c6 populated just with the numbers 4,5,6,8: therefore, these candidates can be eliminated from r2c5 and r3c4
But 5, 6 & 8 are in r2 c5 AND 4 & 8 are in r3 c6
???
Mark
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- Joined: 27 December 2005
by Animator » Thu Jan 19, 2006 9:52 pm
That's why it's a naked quad and not a hiddden quad.
Naked quad = there are 4 cells that have only those 4 candidates. (read: there are 4 cells in which no other number then those 4 are possible)
If you fill in 5, 6, 8 in r2c5 then you end up with an empty cell. (Feel free to try it).
The same is true for r3c6.
Naked quad = there are 4 cells that have only those 4 candidates. (read: there are 4 cells in which no other number then those 4 are possible)
If you fill in 5, 6, 8 in r2c5 then you end up with an empty cell. (Feel free to try it).
The same is true for r3c6.
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Re: Hidden pairs?
by QBasicMac » Thu Jan 19, 2006 11:12 pm
markb wrote:Crazy Girl etc said that the most difficult aspect of these would be a hidden pair.
Hunhh? What's all the talk about quads?
First place the hidden singles in row 1, col 7, row 9 and row 2.
Then see the hidden pair 79 in box 2, right?
Then after placing the 5 in row 2, there are locked candidates: 6 in box 2 and 8 in row 2.
After that, singles to the end.
As Crazy Girl, etc. said: nothing more difficult than one hidden pair.
Mac
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