Equivalence of Recurrence Relations for Feynman Integrals with the Same Total Number of External and Loop Momenta

We show that the problem of solving recurrence relations for L-loop (R + 1)-point Feynman integrals within the method of integration by parts is equivalent to the corresponding problem for (L + R)-loop vacuum or (L + R − 1)-loop propagator-type integrals. Using this property we solve recurrence relations for two-loop massless vertex diagrams, with arbitrary numerators and integer powers of propagators in the case when two legs are on the light cone, by reducing the problem to the well-known solution of the corresponding recurrence relations for massless three-loop propagator diagrams with specific boundary conditions .