disallow concurrent execution attempt explicitly -- it should never happen due to management of singleton execution;
tuned error messages: prefer plain "error" as in document.ML;
(* Title: HOL/NSA/Hyperreal.thy
Author: Jacques Fleuriot, Cambridge University Computer Laboratory
Copyright 1998 University of Cambridge
Construction of the Hyperreals by the Ultrapower Construction
and mechanization of Nonstandard Real Analysis
*)
theory Hyperreal
imports HLog
begin
end