Puzzle with only naked singles or hidden singles?

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Puzzle with only naked singles or hidden singles?

Postby AR4793 » Wed Sep 29, 2010 7:17 pm

Is there a know puzzle which only used hidden singles to solve?

How about a puzzle only using naked singles?

Thanks,
Herb
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Re: Puzzle with only naked singles or hidden singles?

Postby ronk » Wed Sep 29, 2010 7:37 pm

AR4793 wrote:Is there a know puzzle which only used hidden singles to solve?

How about a puzzle only using naked singles?

Courtesy of the Patterns Game, here are six puzzles that can be solved with only hidden singles ...

Code: Select all
1..2..3...2..1..4...3..5..67..6..5...5..8..7...8..4..18..7..4...3..6..2...9..2..7
..1...2.....3.4...5...6...1.5.1.2.7...8...4...2.9.7.8.9...7...8...5.9.....3...7..
1...2...3.4.....1...5.4.6.....2.1...7.8...1.5...4.8.....7.6.8...8.....2.4...3...7
1...2...3.4.....5....6.7.....5...8..7...8...2..6...9.....8.2....1.....6.2...7...1
1..2..3......4..5...6..7..82.....7...5..1..4...7.....98..1..2...6..2......4..6..7
...........12.34...235.617..35...74.....3.....76...82..143.825...87.23...........

and six solvable with only naked singles.

Code: Select all
..........1.2.3.4....456....47...89...2.7.6...98...75....684....3.7.1.6..........
..4...9...37...54.19.....38...1.3......589......2.4...46.....89.12...36...5...7..
1.2...3.......4.5.5.6.2...7...1...4...5...8...3...6...7...9.1.8.8.3.......4...9.6
......1......2..34..3.5.67..1...2..8..4.6.5..3..1...2..95.4.8..68..1......2......
......9......2..36..8.9.47..7...2..1..4.6.7..6..3...2..92.4.8..38..1......7......
..9.8.7...6...5.4.3.....5.2.......3.6...7.4...8.......2.7.1...3.4.7...9...5...8..
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Re: Puzzle with only naked singles or hidden singles?

Postby AR4793 » Wed Sep 29, 2010 8:11 pm

ronk,

Thanks!

I've been trying to decide which is the more primitive between naked singles and hidden singles. It has to be naked singles.

As your puzzles show, puzzles can be created which can be solved only by invoking a rule operating on naked singles.

However it is impossible to create a puzzle that can only be solved with hidden singles. LOL when I figured it out. Think of the last cell to be filled. It has to be a naked single.

Thanks again,
Herb
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Posts: 13
Joined: 26 September 2010

Re: Puzzle with only naked singles or hidden singles?

Postby ronk » Thu Sep 30, 2010 1:33 am

AR4793 wrote:However it is impossible to create a puzzle that can only be solved with hidden singles. LOL when I figured it out. Think of the last cell to be filled. It has to be a naked single.

When there is only one unfilled cell in a unit (row, column or box), it is simultaneously a naked and hidden single.
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puzzles with only "hidden singles"

Postby Pat » Tue Oct 12, 2010 11:24 am


    in the now-lost discussion on
    difficulty evaluation of sudokus with only hidden singles { t=14605 }
    i had posted --

      .5....63.9..1........4......32.8.......6..1........4..7...32.8.1.....9...........
      18 clues
      by gfroyle/gsf
      -- solves in 19 steps of "hidden singles"
    others then posted even more extreme results
    which unfortunately i didn't save---
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