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Poster
LoCo: Local Contrastive Representation Learning
Yuwen Xiong · Mengye Ren · Raquel Urtasun

Thu Dec 10 09:00 AM -- 11:00 AM (PST) @ Poster Session 5 #1699
in Poster Session 6 »

Deep neural nets typically perform end-to-end backpropagation to learn the weights, a procedure that creates synchronization constraints in the weight update step across layers and is not biologically plausible. Recent advances in unsupervised contrastive representation learning invite the question of whether a learning algorithm can also be made local, that is, the updates of lower layers do not directly depend on the computation of upper layers. While Greedy InfoMax separately learns each block with a local objective, we found that it consistently hurts readout accuracy in state-of-the-art unsupervised contrastive learning algorithms, possibly due to the greedy objective as well as gradient isolation. In this work, we discover that by overlapping local blocks stacking on top of each other, we effectively increase the decoder depth and allow upper blocks to implicitly send feedbacks to lower blocks. This simple design closes the performance gap between local learning and end-to-end contrastive learning algorithms for the first time. Aside from standard ImageNet experiments, we also show results on complex downstream tasks such as object detection and instance segmentation directly using readout features.

[Paper]

Author Information

Yuwen Xiong (Uber ATG / University of Toronto)
Mengye Ren (University of Toronto / Uber ATG)
Raquel Urtasun (Uber ATG)

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