The New Sudoku Players' Forum

[tso]

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 2 . 5 | . . . | . 1 9
 9 . . | . . . | . 4 .
 4 6 . | 8 1 . | . . 2
-------+-------+------
 . . . | 1 7 4 | . . .
 . . . | . 8 . | . . .
 . . . | 6 2 5 | . . .
-------+-------+------
 7 . . | . 4 2 | . 6 8
 . 4 . | . . . | . . 5
 3 9 . | . . . | 2 . 4


This puzzle needs *nothing* but naked and hidden singles until only 22 cells are left. No need to use pencil marks until then. At that point, fill in pencil marks in *only* the cells that you can narrow down to exactly 2 candidates. You'll find an xy-type forcing chain only 5 cells long -- then nothing but net.

Though forcing chains are an advanced tactic, I think even a relative novice could crack it in a short while. (Pappocom rates it as invalid.) It would be nice to be able to create/find puzzles like this at will. It's easier to practice finding forcing chains when you know they are there.

[r.e.s.]

I can't resist Sherlocking instead ...
The candidates for row 5 and row 6 after the simpler moves are

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  15   7    46   | 9    8    3    | 456  2    16   
  18   3    49   | 6    2    5    | 47   89   17   


row 5 has only three allowable possibilities:

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  1    .    4      .    .    .      5    .    6       (A)
  5    .    6      .    .    .      4    .    1       (B)
  5    .    4      .    .    .      6    .    1       (C)  <--

row 6 has only two allowable possibilities:

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  1    .    9      .    .    .      4    8    7       (D)  <--
  8    .    4      .    .    .      7    9    1       (E)

(C,D) is the only compatible pair.