27 research outputs found
From polygons and symbols to polylogarithmic functions
We present a review of the symbol map, a mathematical tool that can be useful
in simplifying expressions among multiple polylogarithms, and recall its main
properties. A recipe is given for how to obtain the symbol of a multiple
polylogarithm in terms of the combinatorial properties of an associated rooted
decorated polygon. We also outline a systematic approach to constructing a
function corresponding to a given symbol, and illustrate it in the particular
case of harmonic polylogarithms up to weight four. Furthermore, part of the
ambiguity of this process is highlighted by exhibiting a family of non-trivial
elements in the kernel of the symbol map for arbitrary weight.Comment: 75 pages. Mathematica files with the expression of all HPLs up to
weight 4 in terms of the spanning set are include