How to exclude a type definition from WSDL

Hi,

I have a web service which returns a strongly typed
dataset to its client. This typed dataset was defined in
a class library which was referenced by both the web
service and the client.

The problem I have now is: because the typed dataset was
in the web method's parameter list, its definition was
included in the WSDL and proxy class. Because the client
needs to have both the web reference and the reference to
the class library, the dataset definition in the proxy
class conflicts with its original version in the class
library.

My question is:

1. How to instruct the web service not to include the
definition of the typed dataset in its WSDL and proxy
class?

2. Is this approach (having both the web service and its
client referencing to the same class library) a correct
one? If not, what is the correct one?

3. Is it a good approach for a web service to return a
strongly typed dataset? I tried to let it only return a
untyped DataSet, but I didn't find a efficient way at the
client side to wrap the untyped dataset into a strongly
typed dataset. A copy is not efficient.

Thanks!

Frank