Given two chains we can label them A and B. A+ and A- will indicate the alternating states so that EITHER all of A+ are true OR all of A- are true. We don't know which way round yet. Similarly B+ and B- indicate alternating true/false for that chain. C+ and C- continues the theme if there are more chains on the same candidate number. Given A+, A-, B+ and B- we can colour them on the board to see the patterns.
Let’s look at the multi-colouring rules.
**Type 1 Multi-Colouring **
The Rule is as follows: If A+ shares a unit with B+ and B- then A+ must be the false candidate since either B+ or B- must be true.
We can see above that E3(A+) can see E7(B+)
and G1(A+) can see G6(B-). None of the A+ cells can be 4.
This second example illustrates the idea further, based on candidate 9. The B chain is a single pair. |