doc-src/TutorialI/Misc/arith2.thy

fully enclose "\isadigit{...}";
\<^foo> produces "\isactrlfoo ";

(*<*)
theory arith2 = Main:;
(*>*)
lemma "min i (max j (k*k)) = max (min (k*k) i) (min i (j::nat))";
apply(arith);
(**)(*<*)
done
end
(*>*)