Papers › Multi-Task Learning as Multi-Objective Optimization

Multi-Task Learning as Multi-Objective Optimization

10 Oct 2018NeurIPS 2018 12arXiv:1810.04650archive 2025-07-28

Ozan Sener, Vladlen Koltun

In multi-task learning, multiple tasks are solved jointly, sharing inductive bias between them. Multi-task learning is inherently a multi-objective problem because different tasks may conflict, necessitating a trade-off. A common compromise is to optimize a proxy objective that minimizes a weighted linear combination of per-task losses. However, this workaround is only valid when the tasks do not compete, which is rarely the case. In this paper, we explicitly cast multi-task learning as multi-objective optimization, with the overall objective of finding a Pareto optimal solution. To this end, we use algorithms developed in the gradient-based multi-objective optimization literature. These algorithms are not directly applicable to large-scale learning problems since they scale poorly with the dimensionality of the gradients and the number of tasks. We therefore propose an upper bound for the multi-objective loss and show that it can be optimized efficiently. We further prove that optimizing this upper bound yields a Pareto optimal solution under realistic assumptions. We apply our method to a variety of multi-task deep learning problems including digit classification, scene understanding (joint semantic segmentation, instance segmentation, and depth estimation), and multi-label classification. Our method produces higher-performing models than recent multi-task learning formulations or per-task training.

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IntelVCL/MultiObjectiveOptimization officialmentioned on GitHubpytorchMIT report
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conv3x3 IntelVCL/MultiObjectiveOptimization/multi_task/models/pspnet.py official repository ran · our draft was wrong MIT (permissive) · dbcb53696bc43ef9 · report
conv3x3_bn_relu IntelVCL/MultiObjectiveOptimization/multi_task/models/pspnet.py official repository ran · our draft was wrong MIT (permissive) · fca7e85d958618dd · report
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gradient_normalizers IntelVCL/MultiObjectiveOptimization/multi_task/min_norm_solvers.py official repository unverified MIT (permissive) · faa96c0ba935fc57 · report
l1_loss_depth IntelVCL/MultiObjectiveOptimization/multi_task/losses.py official repository unverified MIT (permissive) · e870ff8870d18569 · report
nll IntelVCL/MultiObjectiveOptimization/multi_task/losses.py official repository unverified MIT (permissive) · a90eec2e662e141f · report
resnet101 IntelVCL/MultiObjectiveOptimization/multi_task/models/resnet_mit.py official repository unverified MIT (permissive) · deddf757c7ef17c5 · report
resnet50 IntelVCL/MultiObjectiveOptimization/multi_task/models/resnet_mit.py official repository unverified MIT (permissive) · db1b66fff0c3985f · report
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Tasks

Depth EstimationGeneral ClassificationInductive BiasInstance SegmentationMUlTI-LABEL-ClASSIFICATIONMulti-Label ClassificationMulti-Task LearningScene UnderstandingSemantic Segmentation

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Results from the paper archive 2025-07-28

TaskDatasetModelMetricValueRank at snapshotLeaderboardReport
Multi-Task Learning CelebA MGDA-UB Error 8.25 #1 of 1 Archive leaderboard report
Multi-Task Learning Cityscapes test MultiObjectiveOptimization mIoU 66.63 #3 of 3 Archive leaderboard report

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