The observation that the renormalization constants in minimal subtraction schemes are independent on mass scales led to efficient ways to compute renormalization
group functions at high orders in perturbation theory. In particular, calculations drastically simplify by using the trick of infrared rearrangement, supplemented
with the subtraction of the infrared singularities of each Feynman diagram by means of the proper counterterms, known as the R* operation introduced in the 80s by
Chetyrkin, Tkachov and Smirnov. This method is still quite complicated at high loop order, because of the large number of diagrams, and it was improved by
Chetyrkin with the so-called global R* operation, which generates a single counterterm to subtract all the infrared poles. In this talk I will review the main
ideas of this method and discuss modern applications.
