The New Sudoku Players' Forum

[Mada]

In one box on my grid I have the following combination:

Code: Select all

+-------------
|123 123 23
|41 6 97
|6 74 98


Is it a naked quad 1234?
It is exactly four candidates in four cells.
So can I jump dirrectly to:

Code: Select all

+------------
|123 123 23
|4 6 9
|6 7 8


Thanks
Mada[/code]

[daj95376]

In one box on my grid I have the following combination:

Code: Select all

+-------------
|123 123 23
|41 6 97
|6 74 98


Is it a naked quad 1234?
It is exactly four candidates in four cells.
So can I jump dirrectly to:

Code: Select all

+------------
|123 123 23
|4 6 9
|6 7 8


Thanks
Mada

What you need to be concerned about most is that there are two cells with just <6> in them.

[RW]

In one box on my grid I have the following combination:

Code: Select all

+-------------
|123 123 23
|41  6   97
|6   74  98


Is it a naked quad 1234?
It is exactly four candidates in four cells.

You don't have exactly four candidates in four cells, there's five different candidates in those four cells. But you do have exactly three candidates in three cells, a naked triple. You also have exactly four candidates that are restricted to four cells, a hidden quad. You also have one candidate restricted to exactly one cell, a hidden single. Once that single is solved, you get the next hidden single and so on. No need for any subsets at all. Then there is of course the two 6's that daj pointed out... let's hope it was a typo.

[Edit: sorry, didn't read your post properly... Of course there is a 1234 naked quad, the 123 naked triple was so obvious that I somehow assumed that you meant the other four cells... That said, there is a naked quad, a naked triple and a hidden triple, and of course the hidden single.]

RW

[Sped]

In one box on my grid I have the following combination:

Code: Select all

+-------------
|123 123 23
|41 6 97
|6 74 98


Is it a naked quad 1234?

As was pointed out, with 2 single 6s in the box, something is wrong. Also, there is a naked triple 123.

But, the 1234 naked quad is there, and it lets you exclude that 4.

[Mada]

First of all – I have to apologize for my wrong grid – with two singles.
Second of all – thank you for your response.
I tried to create the grid where four cells have exactly four candidates, but one candidate appears only once. I.e.
123 23 12 24
and I didn’t recognized that it is simple naked triple – and very easy solution.
I tried to go too deep.
My concern was also situation where is the following combination

Code: Select all

123 235 12
24 567 67
78 58 9


It is only hypothetical box.
We have 123 235 12 24 – set of 1234 – so 5 can be eliminated
We also have
567 67 78 – set of 567 – so 8 can be eliminated
I’m not sure if it is correct to have one cell in the subset where the particular candidate appears only once.
Once again – sorry for my mistake on the beginning
Thanks in advance
Mada

[udosuk]

My concern was also situation where is the following combination

Code: Select all

123 235 12
24 567 67
78 58 9


It is only hypothetical box.
We have 123 235 12 24 – set of 1234 – so 5 can be eliminated
We also have
567 67 78 – set of 567 – so 8 can be eliminated
I'm not sure if it is correct to have one cell in the subset where the particular candidate appears only once.

On the first set you can eliminate the 5, but it's not Naked Quad. Instead it's a Hidden Quad - the 4 cells are the only possible cells in the block to hold {1,2,3,4}. Another way to look at it is you have only {5,6,7,8} in r2c23+r3c12, a Naked Quad, so the 5 must be eliminated from r1c123+r2c1 there.

Your 2nd eliminiation of 8 is wrong. It's neither a naked triple nor a hidden triple, so you can't eliminate anything from those 3 cells. In fact if you don't eliminate the 8 there, the block would still be valid, as in:

Code: Select all

123 23 12
  4 67 67
  8  5  9

[Mada]

Thanks a lot udosuk.
Now I got it.

123 235 12
24

it is Hidden Quad - even if there is one cel with only one candidate.

123 235 12
24 567 67
78 58 9

There is no triple 678 because of {235}
Once again thanks a lot again

[udosuk]

Thanks a lot udosuk.
Now I got it.

123 235 12
24

it is Hidden Quad - even if there is one cel with only one candidate.

In fact it's a hidden single of 4 in r2c1, then a hidden triple of {123} in r1c123, allowing you to eliminate 5 from r1c2 (235). But yes you can treat it as a hidden quad as a whole, just not many players would use it when they can find a naked/hidden single to work with.

123 235 12
24 567 67
78 58 9

There is no triple 678 because of {235}
Once again thanks a lot again

It's not a naked triple {678} because of the 5 in r2c2 (567).
It's not a hidden triple {678} because of the 8 in r3c2 (58).