I need my tikz-cd diagrams to have arrows (vertical and horizontal) that mimic \mapsto^* to match the relation in the text. The closest I've managed is to add a label {*} at [pos=1]:


    M \dar \rar[maps to] & N \dar[maps to][pos=1]{*} \\
    M' \rar[maps to][pos=1]{*} & N'
  M' \longmapsto^* N'

MWE output

Not horrible, but definitely off. I can get it closer by using pos=1.1, but I'd prefer a less fiddly solution (that won't break if the arrow's length changes, for instance). It would be especially helpful if I can define a /.style for this arrow so that I can change my existing ones (they already use a custom style).

  • I can think to the decoration TikZ library. But it's just an idea. – egreg Oct 6 '13 at 10:11
  • Instead of pos=1 replace {*} with {} and try label={[pos=1,inner sep=0,outer sep=0]45:${}^*$} in the second one. To be honest the tikz version is better in my opinion. – percusse Oct 6 '13 at 12:21
  • 2
    Does star next to arrowhead in tikz help? – Qrrbrbirlbel Oct 6 '13 at 14:01
  • Ah! Guess I didn't hit on the right search keywords :-) Maybe this is a duplicate? (Unless there are tikz-cd-specific issues. Or maybe I'll end up editing the question to be specifically about a solution I can put in a style.) At any rate, I like the idea in your comment about making just “*” an arrowhead and combining it with the other; that sounds to me like the Right Thing. How would that work? – Luke Maurer Oct 6 '13 at 19:20
  • @percusse It doesn't seem to work unless I give the label= as part of the label options, which defeats the purpose since I don't want to have a label at all (unless there's a real label). – Luke Maurer Oct 9 '13 at 1:04

I realized I could add shorten >=2.5pt to each starred arrow to make the diagram arrow match the text arrow better:


This meets my criterion that the code doesn't depend on the length of the arrow. I still have to add a label manually to each arrow, however, so I still can't define a mapsto* style that encapsulates this.

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