more direct Proof_Context.lookup_free -- bypass redundancy of Proof_Context.check_const;
(* Title: HOL/MicroJava/DFA/Semilattices.thy
Author: Gerwin Klein
Copyright 2003 TUM
*)
section \<open>Semilattices\<close>
(*<*)
theory Semilattices
imports Err Opt Product Listn
begin
end
(*>*)