TeX - LaTeX Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I'm using 2cell (as in this previous question of mine: Natural transformation arrow ).

I'd like to know how to center not just the twocell double arrow, but arrow with its name too. A picture is worth a thousand words:

enter image description here

This diagram is generated by the following code:

$\xymatrix@C+3pc{J\rtwocell<4>^{\Delta(C)}_{\Delta(C')}{\; \; \; \; \; \Delta(f)} & \C}$

I'd like to know how to center the whole $\Downarrow \Delta(f)$, not just the $\Downarrow$.

share|improve this question
Is TikZ also possible? – Marco Daniel Apr 23 '12 at 17:59
@MarcoDaniel: I'd rather stick to xypic. – Bruno Stonek May 18 '12 at 2:45

I don't know whether this can be done with twocell, but with regular xypic you can certainly achieve it:


J \ar@{}[r]|{\Downarrow \Delta(f)} \ar@/_/[r]_{\Delta(C)} \ar@/^/[r]^{\Delta(C)}& C

J \ar@/_/[rr]_{\Delta(C)} \ar@/^/[rr]^{\Delta(C)}& {\Downarrow \Delta(f)} & C

resulting diagrams

Next time please post a complete MWE, even in follow-up questions.

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.