Introduction to generalised Cesaro convergence III
This is the third and last of three papers introducing generalised Cesaro convergence and is split into two parts. In part 1 we introduce the notion of a "Cesaro-adapted scale" and use it to prove the key generalised Cesaro summation/convergence theorems developed in the first paper in this series. We also use it to trivially extend these results to the case of remainder Cesaro summation/convergence relative to arbitrary $z_{0}\in\mathbb{C}$ (not just $z_{0}=0$). In the course of the working we introduce the concepts of "formal symbols" and "formal function elements", which allow us to express many results in extremely compact form and simplify our arguments considerably. Part 2 is self-contained and devoted to further exploring this "formal" world. We express a number of additional results in surprisingly compact form using formal symbols and function elements, and use them to give simple proofs of several non-trivial results. We also investigate their fascinating properties. These include the need to avoid evaluating too early; the consequent need to retain stand-alone zeros (both "to the left" and "to the right") lest they be brought back to life before evaluation; and the need to use continuous limits to resolve singular ratios in final evaluation when required. Finally, we consider in detail the formal extension we have introduced of our Cesaro-adapted scale to a 1-parameter continuum of period-1 functions $\overset{\lor}{q}_{\rho}(\alpha)$, $\rho\in\mathbb{C}$. We analyse their distributional aspects when $\rho\in\mathbb{Z}_{<0}$ and derive their Fourier-series coefficients in general. We conclude with a miscellany of further observations, including a formal re-casting of the general Euler-McLaurin sum formula in very compact form, and a number of additional analytical and combinatorial characteristics of the $\overset{\lor}{q}_{\rho}(\alpha)$ and associated operators.