[math-fun] notation query
I read a paper today which used a notation I do not remember seeing before; I'm curious whether it is common. The paper discussed the union of the reals with a pair of points at infinity by using an overbar over the set R. It didn't explain the notation, but it was clear from the context. For those with utf-8 support: ℝ̅ ≡ ℝ ⋃ { −∞, +∞ } or in TeX: \bar{\mathbb{R}} \def \mathbb{R} \bigcup \{ -\inf, +\inf \} or maybe \overling{\mathbb{R}}. Is that common? Thanks. -JimC -- James Cloos <cloos@jhcloos.com> OpenPGP: 1024D/ED7DAEA6
In my undergraduate topology class, an overbar was commonly used for the closure of a set. Since we're not talking about the complex numbers, the most obvious closure adds +oo and -oo. But yes, they should have said this. At 11:09 AM 9/22/2013, James Cloos wrote:
I read a paper today which used a notation I do not remember seeing before; I'm curious whether it is common. The paper discussed the union of the reals with a pair of points at infinity by using an overbar over the set R.
I agree with Adam: it's common but not universal. Charles Greathouse Analyst/Programmer Case Western Reserve University On Sun, Sep 22, 2013 at 2:34 PM, Henry Baker <hbaker1@pipeline.com> wrote:
In my undergraduate topology class, an overbar was commonly used for the closure of a set. Since we're not talking about the complex numbers, the most obvious closure adds +oo and -oo. But yes, they should have said this.
At 11:09 AM 9/22/2013, James Cloos wrote:
I read a paper today which used a notation I do not remember seeing before; I'm curious whether it is common. The paper discussed the union of the reals with a pair of points at infinity by using an overbar over the set R.
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James Cloos