The New Sudoku Players' Forum

[bat999]

...(EOR)...

That's nailed it for me.

So this
(9=3)r1c8
denotes that r1c8 is a bi-value square and will contain one of the candidates 9 or 3.

(Still thinking about the other stuff)

[JasonLion]

What you say is true, but it doesn't capture exactly what the notation says. The notation says that r1c8 must contain either 3 or 9 or both. From that combined with the basic rules of Sudoku we can deduce that both isn't an option and there can't be any other candidates in that cell. Just keep in mind that distinction between what the notation says and what you can deduce from the notation in this specific example. Otherwise similar notation in other situations could mislead you.