# Common Notation for Sets or Spaces

Is there some good reference (website could be better) to know the meaning of symbols (generally used) for any "special" kind of sets or spaces like $$\mathbb{R}^{2}_{\geq}$$?

I've looked up, without success, in:

1. Enlightening Symbols: A Short History of Mathematical Notation and its Hidden Powers (Mazur, 2016).

2. https://en.wikipedia.org/wiki/List_of_mathematical_symbols_by_subject

• $\mathbb{R}^{2}_{\geq}$ does not look standard to me. It might be intended to mean $\{(x,y)\}$ with $x \ge y$ or $\{(x,y)\}$ with $x \ge 0$ and $y \ge 0$, or something else. I would expected to be defined where you came across it May 28 '20 at 22:33
• $\mathbb{R}^2_{\geq}$ is standard notation for the positive quadrant, including $x$ and $y$ axes. May 28 '20 at 22:35
• I mean, we can't even decide whether $0 \in \mathbb{N}$ or not. May 28 '20 at 22:40
• @JairTaylor: That's a different question. We all know that $\mathbb{N}$ denotes the "natural numbers," which is an example of the OP's question. May 28 '20 at 22:48
• I've found this link, in which there is a list related to what I am looking for: link.springer.com/content/pdf/bbm%3A978-0-387-68628-8%2F1.pdf May 28 '20 at 22:51