Core-shift effect for 3C 111 between all six frequencies taken into account in this work (from 5 GHz to 87.6 GHz). The different colors represent the different methods used to estimate the core shift, as is explained in Sect. 3.2. The black line, r ∝ ν^{−1.29 ± 0.10}, represents a fit of all the points together. The fit performed with the AVG data points gives r ∝ ν^{−1.27 ± 0.17}, implying that k_r = 0.79 ± 0.17. This result is suggestive of a mild dominance of the particle over the magnetic field, in the energy budget.