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#1 2009-03-30 23:48:21

Onyx
Member
Registered: 2009-02-24
Posts: 48

relation :=

Recently I keep seeing this symbol used everywhere, :=, and at first I thought it was a typo, but I've seen it numerous times in different texts. What's the difference between this and the simple equals sign?

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#2 2009-03-31 00:25:25

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: relation :=

This is exactly the same as an equals sign, but used when defining something new.
As an example, if I'm solving a question involving functions f and g, I might say:

"Now we introduce a new function h, where h(x) = f(x) - g(x)."

But that's far too long a sentence for us lazy mathematicians, so instead I say:
"Now consider h := f - g."

I could have also said f - g =: h if I'd wanted.


Why did the vector cross the road?
It wanted to be normal.

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#3 2009-03-31 00:56:36

Onyx
Member
Registered: 2009-02-24
Posts: 48

Re: relation :=

Thanks

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