added delcongs, Delcongs, unsafe_solver, safe_solver, HOL_basic_ss,
safe_asm_more_full_simp_ta, clasimpset HOL_css with modification functions
new addss (old version retained as unsafe_addss),
new Addss (old version retained as Unsafe_Addss),
new auto_tac (old version retained as unsafe_auto_tac),
(* Title: Option.thy
ID: $Id$
Author: Tobias Nipkow
Copyright 1994 TU Muenchen
Datatype 'a option
*)
Option = Arith +
datatype 'a option = None | Some 'a
end