I'm looking for LaTeX directives that I can use in posts to math.SE to make category-theory-style diagrams that use non-horizontal (vertical, slanted, curved) arrows, both "plain" (i.e. the non-horizontal analogues of $\rightarrow$ and $\leftarrow$) and "decorated" (i.e. the non-horizontal analogues of, e.g., $\hookrightarrow$, $\twoheadrightarrow$, $\rightarrowtail$, dashed arrows, etc.). Therefore, I need not only the codes for the various types of arrows, but also the details of the LaTeX environment for specifying the whole diagram.

P.S. By way of illustration of what I'm looking for, below is an example of the best I know how to do (mostly cribbed from a post by another math.SE contributor):

& & A_i & & \newline
& {\scriptstyle v_i} \swarrow & \downarrow {\scriptstyle t_i} & \searrow {\scriptstyle s_i} & \newline 
K & \xrightarrow{k} & \cup A_i & \xrightarrow{u} & A & \rightrightarrows & B

This diagram falls short in several respects. Most seriously, the names of the two morphisms associated with the paired arrow are missing. In addition, all the other arrows should be hooked ($\hookrightarrow$, to indicate that they are inclusions). Furthermore, the arrow labeled $v_i$ should be not only hooked, but also dashed, to indicate that it is unique. Lastly, all the arrows should be longer, and the angles of the slanted ones wrt the horizontal should be shallower, so that the lines going through them pass through the symbols for the domain and codomain objects, as they are supposed to.

Editors: this post would be easier to read if the LaTeX in it were rendered, instead of appearing as source code. I was not able to find how to turn on LaTeX rendering, but if this is possible to do, please go ahead. I'll do better next time.

  • 2
    We don't use MathJax on TeX.SX. This is a deliberate decision - we are interested in LaTeX code, so if people need to show output they upload images.
    – Joseph Wright
    Sep 11, 2011 at 15:27
  • Yes, I figured that this would be the reason for not having LaTeX rendered by default, but I still hoped there may be a way to turn on rendering, since this would be more convenient than uploading images... No biggie. Thanks for the info, and the edits.
    – kjo
    Sep 11, 2011 at 15:33

1 Answer 1


There's a document called "The Comprehensive LATEX Symbol List", available online at http://mirrors.ctan.org/info/symbols/comprehensive/symbols-letter.pdf. It's a massive compilation of all the symbols that various LaTeX packages provide. The MnSymbol package (see pp. 50f of the doc) in particular provides a multitude of arrow styles; hopefully some of them meet your specific requirements. Happy TeXing!

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