Self-evolutionary optimization for Pareto front learning

Simyung Chang, KiYoon Yoo, Jiho Jang, Nojun Kwak

Keywords: Pareto optimal, Multi-objective optimization, Multi-task learning, Evolutionary strategy

Abstract: Multi-task learning (MTL), which aims to improve performance by learning multiple tasks simultaneously, inherently presents an optimization challenge due to multiple objectives. Hence, multi-objective optimization (MOO) approaches have been proposed for multitasking problems. Recent MOO methods approximate multiple optimal solutions (Pareto front) with a single unified model, which is collectively referred to as Pareto front learning (PFL). In this paper, we show that PFL can be re-formulated into another MOO problem with multiple objectives, each of which corresponds to different preference weights for the tasks. We leverage an evolutionary algorithm (EA) to propose a method for PFL called self-evolutionary optimization (SEO) by directly maximizing the hypervolume. By using SEO, the neural network learns to approximate the Pareto front conditioned on multiple hyper-parameters that drastically affect the hypervolume. Then, by generating a population of approximations simply by inferencing the network, the hyper-parameters of the network can be optimized by EA. Utilizing SEO for PFL, we also introduce self-evolutionary Pareto networks (SEPNet), enabling the unified model to approximate the entire Pareto front set that maximizes the hypervolume. Extensive experimental results confirm that SEPNet can find a better Paretofront than the current state-of-the-art methods while minimizing the increase in model size and training cost.

One-sentence Summary: We tackle the problem of Pareto front learning that tries to obtain multiple optimal solutions with a single network by optimizing hyper-parameters using an evolutionary strategy.