Note that it's a single letter R, not a pair of letters I and R. I can understand why you read it as IR, but that's an incorrect way to read the symbol.

2013年7月23日 · $\\mathbb Q$ is used to represent rational numbers. $\\mathbb R$ is used to represent reals. Is there a symbol or convention that represents irrationals. Possibly $\\mathbb R - \\mathbb Q$?

2017年5月2日 · So that leaves iR i R, the second choice most people suggest, as the more viable alternative. This is a symbol that should feel familiar and comfortable to anyone who has studied principal ideals even cursorily. After all, what is a purely imaginary number but a real number multiplied by i i? Even i i itself can be thought of as 1 × i 1 × i.

2014年6月12日 · Why not just define a symbol, say Ra(x) R a (x) and Ir(x) I r (x) to be the rational/irrational part respectively and just notify the reader about the notation?

2014年6月25日 · I have started seeing the "∈" symbol in math. What exactly does it mean? I have tried googling it but google takes the symbol out of the search.

2016年1月2日 · where i i, j j, and k k are natural numbers 1, 2, 3 1, 2, 3. These symbols are widely used in vector and tensor analysis and in differential geometry. There is a relation between them as the following theorem states. Theorem. The following relation holds between the Kronecker's Delta and permutation symbol

2016年1月8日 · Although all answers work, I plead people to NOT abbreviate two- or three- term sums, especially with summation symbols. Conciseness at the expense of readability is not appreciated by any reader. Rather, give names to the messy expressions under the root symbols and leave the sum as it is. Of all the answers, the only one that would not make me foam at the mouth is @celtschk 's.

2018年5月4日 · R2 R 2 is the set of ordered pairs of reals. It could represent the Euclidean plane. R1000 R 1000 is the set of ordered sequences of length 1000 1000 of reals. They presumably wrote it as 2 ⋅ 500 2 ⋅ 500 to show where 1000 1000 came from. It could be an array that is 2 × 500 2 × 500. The power set of the reals is something completely different. It is the set of subsets of the reals, but ...

2016年2月16日 · No common symbols that I know of U ≅ V U ≅ V or U ∼ V U ∼ V is used to indicate that the spaces are isomorphic. Sometimes f: U →∼ V f: U → ∼ V is used to indicate that f f is an isomorphism between the spaces. I don't know of a special symbol for canonical isomorphism. Not sure what you mean here.

So, I'm wondering why mathematicians use the symbols like $\\mathbb R$, $\\mathbb Z$, etc... to represent the real and integers number for instance. I thought that's because these sets are a kind of