Although multi-task deep neural network (DNN) models have computation and storage benefits over individual single-task DNN models, they can be further optimized via model compression. Numerous structured pruning methods are already developed that can readily achieve speedups in single-task models, but the pruning of multi-task networks has not yet been extensively studied. In this work, we investigate the effectiveness of structured pruning on multi-task models. We use an existing single-task filter pruning criterion and also introduce an MTL-based filter pruning criterion for estimating the filter importance scores. We prune the model using an iterative pruning strategy with both pruning methods. We show that, with careful hyper-parameter tuning, architectures obtained from different pruning methods do not have significant differences in their performances across tasks when the number of parameters is similar. We also show that iterative structure pruning may not be the best way to achieve a well-performing pruned model because, at extreme pruning levels, there is a high drop in performance across all tasks. But when the same models are randomly initialized and re-trained, they show better results.

本文研究了定结构剪枝在多任务深度神经网络模型中的有效性。通过使用基于现有单任务筛选剪枝标准和基于多任务学习筛选剪枝标准，采用迭代剪枝策略进行剪枝，本文表明在参数数目相似的情况下，与快速单任务DNN相比，DNN多任务可以通过精心的超参数调整实现相似的性能，迭代权重剪枝可能不是实现良好性能剪裁模型的最好方式。

多任务深度神经网络的结构剪枝