The New Sudoku Players' Forum

[goldie5218]

hi guys, am looking for some help please, can handle the straight forward color puzzle but seem to have 'hit a wall ' on this part of a puzzle.
it comes from the list of puzzles @ Simple Suduku 2005 and is listed as colors7.ss puzzle.

On the 47th move of this puzzle the 'hint' says you can erase a single candidate 6 from the cell R1C5 using the colors technique.

There are four cells, each holding a candidate 6 in the block concerned, and i cannot for the life of me figure out how to sequence my colouring to
be able to erase just that particular candidate.

When i use filtering to isolate all the candidate 6's i still cant seem to figure how it allows the erasing of that single candidate.

Please, any help much appreciated

[angusj]

Please, any help much appreciated

Hi goldie.
This should explain why you can exclude that candidate:
http://angusj.com/sudoku/hints.php#colors

[SteveF]

I think this is also the one that comes when downloading the SS program, it certainly seems to fit your description.

Start colouring on 6's from say r1c2 (eg blue). It sounds as if you are already familiar with the concept of looking for pairs in a block / row / column. If you do this you should get one colour r4c5 and the opposite colour in r1c2 (eg green).

The target cell r1c5 is in the same row as one of these cells, r1c2, and the same colunm as the other, r4c5.

This gives a contradiction, as r1c2 (blue) dictates that r1c5 should be blue, while r4c5 (green) dictates that r1c5 should be blue.

Clearly it cannot be both colours so therefore r1c5 cannot be a 6.

There is an example and undoubtedly a better explanation at angusj's great site, who as you probably know gave us the excellent Simple Sudoku program.

[goldie5218]

many thanks angusj and SteveF for your prompt replies,scarey for me to have to admit that i could not see the correct technique from anguj's web site, but thats what happens now and again eh?

But the really great thing about this forum is that generous guys like you two are prepared to help us 'battlers', thanks very much and best regards
cheers! goldie