Simplifying regular expressions further

We describe a cumulative series of transformations to simplify regular expressions, and investigate their effectiveness cost. Transformations depending on increasingly powerful comparisons expressions give results clearly superior commonly used algebraic simplifications. Early in the series, efficient enabled by language-invariant attributes are surprisingly effective. Later expressed languages made feasible bounding size subexpressions which they applied. set out principles our transformations, address some key implementation issues, evaluate systematic test measurements.