  I derive a procedure to generate sum rules for the trace anomalies a and a'.
Linear combinations of Delta a = a_UV-a_IR and Delta a' = a'_UV-a'_IR are
expressed as multiple flow integrals of the two-, three- and four-point
functions of the trace of the stress tensor. Eliminating Delta a', universal
flow invariants are obtained, in particular sum rules for Delta a. The formulas
hold in the most general renormalizable quantum field theory (unitary or not),
interpolating between UV and IR conformal fixed points. I discuss the relevance
of these sum rules for the issue of the irreversibility of the RG flow. The
procedure can be generalized to derive sum rules for the trace anomaly c.
