Mixtures of In-Context Learners

In-context learning (ICL) adapts LLMs by providing demonstrations without fine-tuning the model parameters; however, it is very sensitive to the choice of in-context demonstrations, and processing many demonstrations can be computationally demanding. We propose Mixtures of In-Context Learners (MOICL), a novel approach that uses subsets of demonstrations to train a set of experts via ICL and learns a weighting function to merge their output distributions via gradient-based optimisation. In our experiments, we show performance improvements on 5 out of 7 classification datasets compared to a set of strong baselines (e.g., up to +13% compared to ICL and LENS). Moreover, we improve the Pareto frontier of ICL by reducing the inference time needed to achieve the same performance with fewer demonstrations. Finally, MOICL is more robust to out-ofdomain (up to +11%), imbalanced (up to +49%) and perturbed demonstrations (up to +38%). 1 Nasr, Arthur Conmy, et al. Stealing part of a production language model. In Forty-first International Conference on Machine Learning.