Editing after having imported a LaTeX code

I wonder how to fix those errors after having imported a LaTeX code. For example, I paste the following code from LaTeX

\[
  \xymatrix{
    K(R)\ar[r]\ar[d]^{\operatorname{tr}_{\mathrm{GJ}}}&K(R/I)\ar[d]^{\operatorname{\tr}_{\mathrm{GJ}}}\\
    \operatorname{HC}^-(R)\ar[r]&\operatorname{HC}^-(R/I)
  }
\]

I find that TeXmacs failed to parse them. On the other hand, if I import a LaTeX file including these codes, they will be verbatim. I don’t know what I can do to help TeXmacs parse. I noticed that sometimes TeXmacs parses \xymatrix. I don’t know how to modify the code so that it could be parsed by TeXmacs.