# What does the \ symbol mean, please?

#### pellman

... as in $$\bold{R}^2$$\$$\{\bold{0}\}$$

Used in context here http://books.google.com/books?id=4Y-ownk6ilsC&pg=PA70&lpg=PA70&dq=abraham+marsden+foundation+of+mechanics&source=bl&ots=KGabbhy6XM&sig=MNvhtxISRyHdHGC3waYvSZtd-qg&hl=en&ei=zOnKSfraKp_inQeShsjnCQ&sa=X&oi=book_result&resnum=1&ct=result top of the page.

I've previously seen the notation $$\bold{R}^2-\{\bold{0}\}$$ for the cartesian plane with the origin excluded, so I hesitated to assume that the above notation meant the same thing.

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#### Dragonfall

It means the same thing as R - {0} Actually "X - Y" as is an old notation back when the term "set arithmetic" was still used. So the modern notation is X\Y.

#### CRGreathouse

Homework Helper
Ditto. The LaTeX for that operator is \setminus.

#### pellman

Thanks and thanks.

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