(*  -*- isar -*-

      Example proof document for Isabelle/Isar Proof General.
   
      $Id$

      The first line forces Isabelle/Isar Proof General, otherwise
      you may get the theory mode of ordinary Isabelle Proof General
*)

theory Example = Main:

theorem and_comms: "A & B --> B & A"
proof
  assume "A & B"
  thus "B & A"
  proof
    assume A B
    show ?thesis 
      ..
  qed
qed

end