notation seconde represents a topic that has garnered significant attention and interest. notation - What does := mean? - Mathematics Stack Exchange. It's one common notation for stating that the left-hand side is defined as (in contrast to equal to) the expression on the right-hand side.
notation - Symbol for “such that” (not in set) - Mathematics Stack Exchange. A better, but less common, notation is $\varepsilon$ (formatted with $\varepsilon$). You can find answers and comments related to that latter symbol $\varepsilon$ in the linked posts. notation - What is the mathematical symbol for range?
An unsophisticated question from a neophyte: Given the numbers: $1,2,3,4,5$ What is the symbol for the range of the numbers? It's important to note that, the lowest-highest number in the set. For example, the min max ... This perspective suggests that, notation - Math Symbol for "Where" - Mathematics Stack Exchange. However, the middle signs in set builder (or quantifier) notation are not really catch-all replacements for the words "such that".

Building on this, notation - Correct way for writing domain of a function - Mathematics .... The notation $\ {x \in \mathbb {R} \}$ is a little ambiguous, but would probably be understood. As Eike Schulte points out, there is something missing—either the "selection criterion" which tells you how you are choosing element of $\mathbb {R}$, or you are specifying the name and domain of some variable which will be acted on by some ... notation - Name of a vector of 1s?
From another angle, your notation $\mathbf {1}$ (or $\mathbf {1}^T$ if you insist that $\mathbf {1}$ is a column vector) is fine and is commonly used. Just define it when you are using it. Similarly, notation - What does the function f: x ↦ y mean? - Mathematics Stack ....

Similarly, so, is there any scenario where you would need to use the "↦" notation instead of "=" notation? If your answer is a full explanation, it seems to me that ↦ is entirely useless. Notation for the least common multiple and greatest common divisor. The (bad) notation $ (a,b)$ is often used for the greatest common divisor; somebody uses $ [a,b]$ for the lowest common multiple.
Why are they bad, in particular the former? Because $ (a,b)$ is already used for several other purposes. notation - Difference between "≈", "≃", and "≅" - Mathematics Stack ....

In mathematical notation, what are the usage differences between the various approximately-equal signs "≈", "≃", and "≅"? The Unicode standard lists all of them inside the Mathematical Operators Block. notation - The best symbol for non-negative integers?

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