Either Randy or Vijay, but not both, are chatting. Either Kevin or Heather, or both, are chatting. Is it possible to determine who is chatting if the...

Either Randy or Vijay, but not both, are chatting. Either Kevin or Heather, or both, are chatting. Is it possible to determine who is chatting if the following information is known? If Abby is chatting, so is Randy. Vijay and Kevin are either both chatting or neither is. If Heather is chatting, then so are Abby and Kevin. Explain your reasoning.