Jimmy, multiple agents will not access the variable simultaneously  
unless you have fired them in separate threads.  In the standard  
MASON distribution, this is only possible via ParallelSequence or  
AsynchronousSteppable.  So you'll need to be more specific about what  
you mean here.

As to concurrent access control, Java does this like any other  
multithreaded system.  Create a lock variable that both agents have  
access to -- perhaps an instance variable.  An empty array works nicely:

	Object[] lock = new Object[0];

Then later your agents access the variable of choice like this:

	synchronized(lock)
		{
		// do stuff with my variable
		}

Sean

On Dec 25, 2006, at 3:28 PM, Jimmy Ong wrote:

> Merry Christmas to all!
>
> Can someone show me how do i prevent concurrent access to some  
> variable
> between 2 or more agents? I tried to synchronize on state.schedule  
> or an
> arbitrary object, but it doesn't work.
>
> Thanks in advance,
> Jim.