doc-src/Tutorial/Misc/arith2.ML

removed cases_of;
renamed cases_tac to case_tac; tuned to work with basic HOL as well;
add_cases_induct: proper case names;
adapted to new PureThy.add_thms etc.;

Goal "min i (max j (k*k)) = max (min (k*k) i) (min i (j::nat))";