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[Guest]

I was working on an older puzzle and got stuck. Can someone give me some logic?

6 _ 5 | 1 _ _ | 8 _ 7
_ _ _ | _ _ 7 | _ 5 _
_ 7 9 | _ _ _ | _ 6 1
-----------------------
7 5 _ | _ _ 3 | 6 _ _
4 _ 3 | _ _ _ | 5 7 8
9 _ _ | 4 7 5 | 3 1 2
-----------------------
3 9 _ | _ _ _ | 7 _ _
5 _ 7 | 9 _ _ | 1 _ _
_ _ 4 | 7 _ 8 | 9 _ 5


Thanks,
Rick

[David Bryant]

Your most obvious next move is r3c1 = 8. Here's how to see that.

-- The only apparent possibilities at r3c1 are {2, 8}, because you already have {3, 4, 5, 6, 7, 9} in column 1, and a "1" in r3c9.

-- The only possibilities at r3c7 are {2, 4 } -- you already have seven values entered in column 7.

-- The only possibilities at r3c6 are {2, 4}, because you already have {3, 5, 7, 8} in column 6, and {1, 6, 9} in row 3.

-- Since the two values "2" and "4" must occupy r3c6 & r3c7 in some order, there cannot possibly be a "2" at r3c1. So the only possibility left is an "8". dcb