Hi-I like handy rules like the Sylvester rule- if one player leads in 2 of 3 (Position -race- thread) then it should be double- take.
Could someone further explain it- for example -is it still a take when the oponent has a lead in position and thread, but the race is equal, or do I need an edge in the race for taking?

It's a very good general rule, but there are plenty of exceptions.

If you're ahead in 2 out of 3, then double-take is the usual result.

If you're ahead in 3 out of 3, it could be double-take or double-pass. A lot of things factor in -- how far ahead in the race, how big are the threats, how strong is the positional edge, etc.

Give us a position and we can take a look at it for you.

Thank you for your quick answer. I hadn't any special position in mind- i just thought it would be possible to define some nuances...
But, anyway, maybe it's just handy in general but better watch each aspect of any position.