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locked candidate

 
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alaska paula



Joined: 07 Aug 2014
Posts: 3
Location: United States

PostPosted: Sun Feb 03, 2019 11:31 pm    Post subject: locked candidate Reply with quote

I don't understand "locked candidate." There is the same # in the same row, column and box.
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immpy



Joined: 06 May 2017
Posts: 217

PostPosted: Sat Mar 09, 2019 4:49 am    Post subject: Reply with quote

Hello Paula,
I am thinking you are referring to "locked candidates", they are plural. If you only had one, good chances are that it would be a "single", either Naked (left all alone in the grid-space) or Hidden (one of multiple candidates possible in the grid-space).
Locked candidates come in two varieties, Pointing and Claiming. Pointing locked candidates occur when a candidate is possible in only two or three places inside of a box, and these places are ALSO in a common row or a common column. Any other candidates of the same value outside of the box, sharing the same row or column, can be eliminated.
Claiming locked candidates occur when a candidate is possible in only two or three places in a row or a column and ALL of these places are within the same box. Any other candidates of the same value inside of that box that do not share the same row or column may be eliminated.

Hoping I shed some light on this.

Immp
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alaska paula



Joined: 07 Aug 2014
Posts: 3
Location: United States

PostPosted: Fri Mar 15, 2019 8:29 pm    Post subject: Reply with quote

Today's puzzle (3/15) is a good example. I don't understand why the 6 in r5c2 is a locked candidate. There is another 6 right above it and also a 6 in the same row at r5c8. Why is that 6 rather than either of the other 2 a locked candidate?
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immpy



Joined: 06 May 2017
Posts: 217

PostPosted: Mon Mar 18, 2019 2:02 am    Post subject: Reply with quote

Paula, it would make things clearer if we knew how much of the puzzle you had solved up to the point when you were given 6 as a locked candidate. I am going to assume a point where you MAY have been solving-wise. Only you can know for sure where you were at any given point.

Here is the puzzle after several moves have been made:

Code:

+---------+-------------+---------------+
| 3 7  2  | 45  16   9  | 8  1456 146   |
| 8 5  9  | 34  136  7  | 46 2    1346  |
| 4 1  6  | 235 23   8  | 7  35   9     |
+---------+-------------+---------------+
| 2 68 17 | 38  378  5  | 46 9    13468 |
| 5 68 3  | 1   9    4  | 2  68   7     |
| 9 4  17 | 6   2378 23 | 5  138  138   |
+---------+-------------+---------------+
| 1 2  58 | 9   458  6  | 3  7    48    |
| 6 3  58 | 7   458  1  | 9  48   248   |
| 7 9  4  | 238 238  23 | 1  68   5     |
+---------+-------------+---------------+

Play this puzzle online at the Daily Sudoku site

You can post these in our forum in this way. Use the Draw/Play screen to solve like you do normally, or you can use pencil and paper, as I do, and then enter all of the numbers you have manually solved up to this point. Then use the Ascii tab (click it) on the right side of the puzzle. A new smaller window will appear with the puzzle inside of it. Simply right-click inside the field of the smaller Ascii puzzle. You should see a drop-down menu, and one of the options will be 'Copy'. Left click 'Copy'. Then close the small window. Now when you are on the forum page, writing your thread, you can right-click inside the thread and then left-click 'Paste', and your puzzle will appear here in your thread.

As to this particular puzzle, there are a few Hidden Singles available at this stage. I understand now that the Hint button in Draw/Play refers to Hidden Singles as a "locked candidate". I see where you are getting this terminology from. There is a Hidden Single of 6 in r9c8, and when it is placed there, then there becomes a Naked Single of 8 in r5c8...which in turn leads to your "locked candidate", or Naked Single of 6 in r5c2.

I hope I was able to enlighten, but as I stated earlier, it really depends on where YOU were in your solving progression, as to what you would see next.

cheers...imp

p.s. as an example of another option, there is also a Hidden Single of 2 in Box 9 @r8c9....if this is placed then the Naked Pair of 48 makes eliminations inside the box9 and along row 8. There are many paths one could use.
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immpy



Joined: 06 May 2017
Posts: 217

PostPosted: Mon Mar 18, 2019 2:21 am    Post subject: Reply with quote

Actually Paula......the Naked Pair of 48 inside of Box9 places the 2 and the 6 in their respective cells, and also leads to your locked candidate @r5c2.

Paula, let me ask you...were you at a similar stage in your solving when you were given the "locked candidate hint" or were you less far along?

Thank you.....immp
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