The New Sudoku Players' Forum

[noeldillabough]

I am writing a sudoku solver and I"ve put in naked pairs (triples, quads) as well as other rules. I however don't have what looks to be a very simple rule:

Using Simple Sudoku I have the following puzzle:

69.|.78|2..
.7.|..2|.6.
2..|.46|..9
-----------
.1.|26.|3.0
...|415|..6
..6|8..|.2.
-----------
7..|.8.|..2
.4.|6..|.5.
...|7..|.83

When I click hint I get "Possibles locked to a column"; what does this mean? And why can 1 be eliminated from (7,4)?

I'ts probably obvious but for whatever reason I've missed it.

[angusj]

When I click hint I get "Possibles locked to a column"; what does this mean?

http://www.angusj.com/sudoku/hints.php#eliminating_candidates_1

[noeldillabough]

Aah such denseness!! I never thought of that. Maybe a case of forest before tree syndrome

After investigation I did indeed have this rule its just I didn't call it anymore when I put in the pairs/triples/quads code. Now I'm going to have to look at swordfish and xwing...those are scaring my little brain!