The vertical bar qualifier explanation is missing, but it's widely used interchangeably with the colon qualifier. Even it the text you use "|" so it should be explained as well.
* Update set-theory.html.markdown
Fixed a minor typo.
* Add files via upload
Added a french translation for set theory.
* Add suggested changes
J'ai fait presque tous les changements suggérés.
* Fix spacing before semicolons
This pull request attempts to fix major inconsistencies and some incorrect information. It also streamlines the article by rearranging and/or removing stubs of information.
- Replaced `v` and `^` set operators with cup and cap, respectively;
- Removed history section as the information was not necessarily accurate;
- Expanded symbols section by splitting it into operators and qualifiers;
- Renamed "builtin sets" to "canonical sets";
- Replaced Latin alphabet symbols for canonical sets with their Blackboard bold variants (see: https://en.wikipedia.org/wiki/Blackboard_bold);
- Rewrote set relations section to streamline information;
- Rewrote examples in set operations section to make meaning more clear;
- Removed generalized operations section, as the original author was clearly trying to typeset unions and intersections of collections of sets, but the notation is impossible to replicate in markdown and only makes the section more unclear.
