doc-src/TutorialI/Misc/arith4.thy

added state: 'a * 'b -> 'a * ('a * 'b);

(*<*)
theory arith4 = Main:;
(*>*)
lemma "\\<not> m < n \\<and> m < n+1 \\<Longrightarrow> m = n";
(**)(*<*)
oops;
end
(*>*)