doc-src/TutorialI/Misc/arith1.thy

begin_theory: store *copy* of initial theory;

(*<*)
theory arith1 = Main:;
(*>*)
lemma "\\<lbrakk> \\<not> m < n; m < n+1 \\<rbrakk> \\<Longrightarrow> m = n";
(**)(*<*)
apply(auto).;
end
(*>*)