**4. Conclusions**

In this article, we have established new relations between the Mittag–Leffler functions of one, two and three parameters by using Riemann–Liouville fractional calculus. The main results are Proposition 1 (three-parameter Mittag–Leffler in terms of two-parameter Mittag–Leffler), and Theorem 2 (three-parameter Mittag–Leffler in terms of one-parameter Mittag–Leffler), which come from combining Proposition 1 with Proposition 2 (two-parameter Mittag–Leffler in terms of one-parameter Mittag–Leffler). We believe that these results can be applied in the future, to simplify some important physical models that use two- or three-parameter Mittag–Leffler functions, or to provide more efficient computational models for these functions, since the original one-parameter Mittag–Leffler function is much better known and more deeply studied.

**Author Contributions:** Conceptualisation, H.M.S.; methodology, H.M.S., A.F., and D.B.; formal analysis, A.F.; writing—original draft preparation, A.F.; writing—review and editing, D.B.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
