On polyhedral formula for Kirillov-Reshetikhin modules
We propose a method to prove a polyhedral branching formula for Kirillov-Reshetikhin modules over a quantum affine algebra. When the underlying simple Lie algebra is of exceptional type, such a formula remains mostly conjectural. We convert a polyhedral formula into an identity between two rational functions of a single variable with only simple poles at known locations. It is then sufficient to check the equalities of the residues at those poles, which are explicitly computable quantities. By following this strategy, we obtain a computer-assisted proof of a conjectural polyhedral formula in type $F_4$.