Good Morning: I have a question about "standard terminology" or "standard methodology". Is there a standard technique to generate the closure of a set through generating the next element from the current? The motivating idea is a simple one: generate a free language from the list of characters. This is a standard inductive process seen in lots of automata and formal language books. Seems like there is product followed by a co-product sort of action. best regards, steve -------- D. E. Stevenson, Department of Computer Science Clemson University, Clemson, SC 29634-0974 864.656.6880 http://www.cs.clemson.edu/~steve