Translating from FOPL to DL

Dear All,

I have seen the translation (pi) from DL to FOPL (e.g. in DL Handbook). 
I am trying to work out how to do the reverse for a very limited subset 
of FOPL (just terms with constants and variables). I'm having a few 
problems with handling the variables in properties. E.g:

A(x) => A

is ok, but:

R(x,y) => \exists R.

seems to wrong.

Has anyone seen/ done anything like this already?

Thanks,

Matt

P.S. Apologies for cross-posting - not sure of the most appropriate 
forum for this.
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