Combinatorics of Newell–Littlewood Numbers

We give an exposition of recent developments in the study of Newell– Littlewood numbers. These are the tensor product multiplicities of Weyl modules in the stable range. They are also the structure coefficients of the Koike–Terada basis of the ring of symmetric functions. Two types of combinatorial results are exhibited, those obtained combinatorially starting from the definition of the numbers, and those that also employ geometric and/or representation theoretic methods.