# How do I make the arrow -->— using xymatrix?

I do not know any TikZ so I cannot use this post, which otherwise is precisely what I am looking for. So how do I make such a square? The best I could come up with was

\ar@{-}[r]^{\delta}|-{>}

but it doesn't look good and does not work on vertical lines/arrows.

Now, having done this square my guess would be that the corners would be empty, that is, the edges would not meet each other. How do I fix that problem?

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