Dashed /^/ in xy package

Question

I am trying to make the following arc between two objects using the /^/ but I need it to be dashed my matrix is as follow:

\xymatrix{
    &0\ar@{-->}[r]&0'\ar@{-->}[l]\\
    &x\ar@{->}[u]\ar@{->}[r]&x'\ar@{->}[u]\\
    &n\ar@{-->}[r]\ar@{->}[u]&n'\ar@{-->}[l]\\
    &b\ar@/^/[uuu]\ar@{-->}[r]&b'\ar@{-->}[l]
    }

Answer 1

The code

\ar@/^/@{-->}[uuu]

seems to give what's expected. You may also try

\ar@/^15pt/@{-->}[uuu]

to increase the bending of the curved arrow.

\xymatrix{
    &0\ar@{-->}[r]&0'\ar@{-->}[l]\\
    &x\ar@{->}[u]\ar@{->}[r]&x'\ar@{->}[u]\\
    &n\ar@{-->}[r]\ar@{->}[u]&n'\ar@{-->}[l]\\
    &b\ar@/^15pt/@{-->}[uuu]\ar@{-->}[r]&b'\ar@{-->}[l]
    }