2013年1月7日 · sorry to disagree, but i think \reflectbox is the correct interpretation here -- it's a mirror image. the only situation in which i'd use \rotatebox is if the symbol were sloped, and the slope had to be retained.

The Unicode character 0x2209 (\notin) does not seem to be included in the Latin Modern Math font. I know that I can load the Unicode character from another font, but I just want the output to look like \not\in in Computer Modern.

2018年6月8日 · Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

What naive set theory usually proves (I am unfamiliar with Halmos' text, so it might not be the case here) is that there is no set "of all the sets which are not members of themselves", that is $\{x\mid x\notin x\}$ is not a set.

$\begingroup$ @user9026 There are indeed no free variables in the axiom (schema) itself. The schema ranges over all formulas $\varphi(x, w_1, \ldots, w_n, z)$ in the language of set theory.

2022年3月2日 · I'm trying to prove the statement without the notion of class. So in the formal language of the Zermelo-Fraenkel axiom I believe we are to stablish $\neg \big[\exists A: \forall x: (x\in A\iff x\no...

2022年6月24日 · I read a proof for the following statement: $ x \in (A\cap B)\setminus C \Rightarrow x \notin A \ominus B \ominus C $ $ \ominus = $ symmetric difference. Here is the proof: $ x \in (A \cap B)\setminus C \Rightarrow x \in A \land x\in B \land x \notin C $. Therefore, $ x \notin (A \ominus B)$. Hence, $ x \notin (A\ominus B)\ominus C $.

Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Stack Exchange Network. Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

(On a lighter note, it could also avoid confusion between \nothing and \notin in casual conversation :-) For comparison, the four simple candidates for 'nothing' or the 'empty set' (\phi and \Phi are not candidates) are shown below with \not= to ease comparison of the angle of the empty set slash (a concern for some users), where appropriate.