IBIS (Inverse BInomial sum Solver) is a FORM program that expresses inverse binomial sums in terms of S-sums while retaining analytic dependence on the upper summation limit. It supports fixed-sign and sign-alternating sums containing zero, one, or two harmonic sums. Together with the included helper procedures and the Summer package, a larger class of sums can be prepared for evaluation.
IBIS was developed by Paul van Hoegaerden, Coenraad Marinissen and Wouter Waalewijn. If you use IBIS, please cite the relevant paper.
Detailed installation and usage instructions, including input preparation, helper procedures, examples, output processing and troubleshooting, are available in the IBIS manual.
IBIS relies on FORM, which can be found in its GitHub repository.